An Expeditious Modular Hybrid Strategy for the Diversity-Oriented Synthesis of Lamellarins/Azalamellarins with Anticancer Cytotoxicity

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An Expeditious Modular Hybrid Strategy for the Diversity-Oriented

Synthesis of Lamellarins/Azalamellarins with Anticancer

Cytotoxicity

Kanawut Klumthong, Papornchanok Chalermsub, Pattarawut Sopha, Somsak Ruchirawat,

and Poonsakdi Ploypradith *

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ABSTRACT: A modular hybrid strategy has been developed for

the diversity-oriented synthesis of lamellarins/azalamellarins. The

common pentacyclic pyrrolodihydroisoquinoline lactone/lactam

core was formed via the Michael addition/ring closure (Mi-RC)

and the copper(I) thiophene-2-carboxylate (CuTC)-catalyzed C−

O/C−N Ullmann coupling. Subsequent direct functionalization at

C1, DDQ-mediated C5C6 oxidation, and global deprotection of

all benzyl-type O- and N-protecting groups furnished the desired

lamellarins/azalamellarins. The late-stage functionalization at C1

provided a handle to accommodate a wider scope of functional

groups as they need to tolerate only the DDQ oxidation and global

deprotection. Moreover, with the C1-H pyrrole as the late-stage

common intermediate, it was also possible to divergently exploit

not only its nucleophilic nature to react with some electrophilic species but also some transition-metal-catalyzed cross-coupling

reactions (via the intermediacy of the C1-iodopyrrole) to incorporate diversity at this position. Overall, this strategy simpliﬁes the

preparation of lamellarins/azalamellarins; including the Mi-RC, these C1-structurally diverse analogues could be prepared eﬃciently

in 6−7 steps from the easily accessed 1-acetoxymethyldihydroisoquinoline and β-nitrocinnamate. Some selected azalamellarins were

evaluated for their inhibitory eﬀect against HeLa cervical cancer cells. An acute induction of intrinsic apoptosis was detected and may

lead to growth suppression of or cytotoxicity against cancer cells.

Scheme 1. Lamellarins (1) and Their Aza Analogues (2)

INTRODUCTION

■

Lamellarins (1) are a group of marine-derived natural

products. Since their ﬁrst reported isolation in 1985 by

Faulkner,¹a number of natural as well as unnatural analogues

have been isolated²or synthesized by various groups including

ours.³⁻⁶Lamellarins and their analogues have been shown to

exhibit a wide array of biological activities as well as a reversal

against multidrug resistance in some cancer cell lines,

inhibition against HIV-1 integrase, and immunomodula-

tion.⁷⁻¹⁰In addition, some studies toward elucidating

molecular mechanisms for anticancer activities have been

conducted.¹¹Topoisomerase poisoning,¹²inhibition of cancer-

related protein kinases,^7b,f,9and interfering with mitochondria

functions¹³have been suggested as plausible mechanisms

leading to apoptosis and eventual cell death.

lar.^{4a,e,f,h,5b,c,e,g,h,6,7e,8b}The pyrrole functionalization, on the

other hand, while highly modular with each unit possibly

Diﬀerent synthetic strategies have been developed; they can

be classiﬁed into two approaches: pyrrole formation and

pyrrole functionalization (Scheme 1).¹⁴Because the con-

vergent nature of the pyrrole formation approach requires the

early sequential preassembly of the requisite synthons with the

selected substituents around the core prior to the pyrrole

formation step, this renders the approach less modu-

Received: July 11, 2021

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Scheme 2. Retrosynthetic Analysis of the Pyrrole Formation Route (I) and the Hybrid Strategy (II)

incorporated rather orthogonally to others via the sequential

Pd-catalyzed Suzuki cross-coupling reactions, is seemingly

more linear, resulting in a relatively higher overall number of

steps and lower yields.^{4b,c,5f,i,7a,8c,d,9a,b,10b}In addition, both

approaches suﬀer from a limited range of functional group

compatibility, arising mostly from incorporating functionalized

aromatic rings at an early stage (pyrrole formation) or various

stages (pyrrole functionalization). Thus, it is desirable to

develop a hybrid strategy whereby the advantages from both

approaches can be realized, combined, and maximally

utilized.^4d,g,5aHerein, we wish to report our development of

such a hybrid strategy to expedite the preparation of

lamellarins (containing lactone) as well as their aza

analogues^5i,7d,f,9d(azalamellarins (2); containing lactam).

As shown retrosynthetically in Scheme 2, when compared

with our previously developed approaches for lamellarins and

azalamellarins (I), which required the incorporation of the

nonfused aromatic group at an early stage,^6,7d,fthe hybrid

strategy (II) would incorporate such group at C1 at a late stage

to divergently deliver structurally diverse analogues from a

common pentacyclic core 3a or 3b. The pyrrole formation

would still rely on the highly convergent Michael addition-ring

closure (Mi-RC) Grob-type condensation⁶between either the

benzyldihydroisoquinoline 4 and the β-nitrocinnamate 5 (I) or

the dihydroisoquinoline acetate 6 and compound 5 (II).^7eThe

dihydroisoquinoline acetate 6 would require only one

benzaldehyde 7 as the starting material without the need for

the benzaldehyde 8 because such unit would be installed at a

later stage via electrophilic aromatic substitution (for 3a) or

Pd-catalyzed cross-coupling reactions (for 3b). The β-nitro-

cinnamate 5 could be prepared from benzaldehyde 9. In

addition, both I and II would utilize the Ullmann-type C−O/

C−N bond formation for the lactone/lactam ring, respective-

ly.^7d−f

Scheme 3. A Convergent Decagram-Scale Synthesis of

Pyrrole Ester 15 via Mi-RC

bromoacetyl bromide (87% yield) and then acetoxylation using

acetic acid and potassium carbonate (82% yield) to provide the

requisite acetoxy amide 12 in 48% yield over ﬁve steps starting

from isovanillin 10. A subsequent Bischler−Napieralski

reaction of 12 gave the imine, which was not puriﬁed but

employed directly for the ensuing Mi-RC Grob-type

condensation^6c−ewith β-nitrocinnamate 13, available in 67%

yield from the commercially available vanillin 14 over three

steps, to aﬀord the pyrrole ester 15 in 51% yield over two

steps. Notably, the robustness of these steps allowed for a

highly reproducible decagram-scale synthesis.¹⁵

With the pyrrole ester 15 in hand, we next turned our

attention to the formation of the remaining lactone/lactam

ring (ring B; Scheme 1) of the pentacyclic skeleton. Ideally, the

pyrrole ester 15 was anticipated to serve as a common

intermediate to access the lactone/lactam ring. While such

consideration was proven successful earlier, the substrates for

such transformations were fully substituted pyrroles with an

aromatic group at C1 of the lamellarin framework.^7fIn this

case, the C1-H in the nonfully substituted pyrrole 15 may have

diﬀerent reactivity, which may or may not be compatible with

the chemistry required for the lactone/lactam formation. To

RESULTS AND DISCUSSION

■

Chemistry. On the basis of our previous structure−activity

relationship studies,^7c−fwe decided to employ the commer-

cially available isovanillin (10) as our starting material. As

shown in Scheme 3, a two-step sequence of benzylation and

Henry aldol condensation smoothly converted 10 to the

corresponding β-nitrostyrene 11 (68% yield), which was

subjected to LiAlH₄reduction to yield the corresponding

aryl ethylamine, which underwent amidation reaction using

B

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our delight, saponiﬁcation of the ester could be aﬀected by

using NaNH₂in “non-dried” 1,4-dioxane to aﬀord the

corresponding carboxylate,¹⁶which was not isolated but

directly subjected to the copper(I)-thiophene carboxylate

(CuTC)-catalyzed Ullmann-type C−O bond formation¹⁷

using Cs₂CO₃as a base with microwave irradiation to furnish

the lactone 16 in 80% yield over two steps (Scheme 4).

Table 1. Optimization of CuTC-Mediated C−N Bond

a

Formation

Scheme 4. Access to Pyrrole Lactones and Lactams 16−19

from the Ester 15

b

entry

CuTC (mol %)

time (min)

yield (%)

1

2

3

4

5

6

7

8

9

10

300

200

100

10

40

30

20

10

5

22

28

31

35

46

53

56

60

90

0

5

0

a

Unless otherwise noted, reactions were performed in N,N-

dimethylformamide (DMF) under microwave irradiation (150 °C;

b

300 W; 250 psi) for the time as speciﬁed for each entry. Isolated

yields.

conventional heating with a prolonged reaction time (reﬂuxing

1,4-dioxane for 6 h), which gave the desired product in a

similar yield.

On the basis of previous structure−activity relationship

studies, which revealed that the natural/unnatural analogues

with C5C6 oleﬁn on the D rings exhibited higher potency in

various biological assays,^7c−ewe then focused on preparing

another advanced intermediate via C5−C6 oxidation to the

corresponding oleﬁn. Disappointingly, all our attempts to carry

out such oxidation under various conditions including the use

of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or

cerium ammonium nitrate (CAN)¹⁸on pyrroles 16−19 were

futile, indicating the chemical incompatibility between either

the hydrogen or iodine atom on the pyrrole at C1 with

oxidizing conditions. We then considered delaying this

oxidation until at a later stage, i.e., after C1 functionalization,

the step at which incorporation of other groups deemed

compatible with oxidation would be performed. Two types of

C1 functionalization were contemplated: (a) electrophilic

aromatic substitution exploiting the nucleophilic nature of the

unsubstituted pyrrole lactone 16 and lactam 17 and (b)

transition-metal-catalyzed cross-coupling reactions of the

iodide 18−19. Because some of our previous work involved

lamellarin D and N as well as their aza analogues, we decided

to evaluate the transition-metal-catalyzed cross-coupling

reactions ﬁrst by allowing the iodide 18 to react with the

corresponding arylboronic acid under a standard Pd-catalyzed

Suzuki cross-coupling condition,¹⁹which yielded the desired

O-benzylated lamellarin χ (Scheme 5). Subsequent DDQ-

mediated C5−C6 oxidation then gave 21 in 64% yield over 2

steps. Global debenzylation using triﬂuoroacetic acid and

thioanisole furnished lamellarin D (22) in 82% yield.^7f

Similarly, lamellarin 23 bearing an unsubstituted phenyl ring

at C1 was successfully prepared from 18 using phenylboronic

acid for the Suzuki cross-coupling reaction and DDQ oxidation

(75% yield, 2 steps) followed by global O-debenzylation

(72%).

Alternatively, also by a two-step process, the ester group of 15

could be converted directly using Me₃Al, in 86% yield, to the

corresponding PMB amide, which underwent the CuTC-

catalyzed microwave-assisted Ullmann-type C−N bond for-

mation¹⁷to furnish the lactam 17 in 90% yield following some

optimization (Table 1). Subsequent iodination of both lactone

16 and lactam 17 furnished the iodopyrrole lactone 18 and

lactam 19 in 67% and 85% yields, respectively.

As shown in Table 1, despite the previous optimization for

this C−N bond formation which entailed the use of 3 equiv of

CuTC for the synthesis of azalamellarin D and N under similar

reaction conditions,^7fwe found that, for the pyrrole amide 20,

using such amount of CuTC with the reaction time of 40 min

under microwave irradiation gave 17 only in a low yield (22%,

entry 1). After some experimentation, we found that reducing

the amount of CuTC to 2 equiv proved slightly beneﬁcial for

the yield (28%, entry 2), while decreasing the reaction time

signiﬁcantly improved the yields (up to 53%; entries 3−6). A

combination of lowering the amount of CuTC to 1 equiv and

the reaction time to 5 min only improve the yield slightly

(56%, entry 7). Interestingly, employing only a catalytic

amount of CuTC (5−10 mol %) furnished 17 in better yields

of up to 90% (entries 8 and 9). As a control, no reaction took

place in the absence of CuTC under otherwise an identical

reaction condition (entry 10). For the decagram scale, without

the use of a microwave, this step could be performed using

C

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Because azalamellarins have been shown to exhibit

cytotoxicity at a comparable level to that of the corresponding

lamellarins,^7d−fwe decided to perform this reaction sequence

on the iodopyrrole lactam 19. As shown in Table 2, a number

of arylboronic acid derivatives could react with 19 to furnish

the corresponding products 24a−24p in low to excellent yields

(12−92%) most of which could be further oxidized using

DDQ as a reagent to the C5C6 products 25a−25p in

moderate to good yields (32−89%). Global O- and N-

deprotection of the benzyl-type protecting groups delivered the

ﬁnal azalamellarins 26a−26p in moderate to good yields (33−

85%). Overall, diversely C1-substituted azalamellarins 26a−

26j and 26l−26m could be obtained from iodopyrrole 19 in

7.6−68% yields over 3 steps. It should be noted that DDQ

oxidation was found incompatible with oleﬁn-containing

moieties (entries 14 and 15). In addition, the methyl group

was also oxidized to the corresponding aldehyde, which

decomposed under the reaction condition (entry 16).

Interestingly, the pyridine moiety of 24k survived the DDQ

Scheme 5. Synthesis of Lamellarin D (22) and C1-Ph

Derivative 23 from the Iodolactone 18

Table 2. Reaction Sequence of Suzuki Cross-Coupling with 19, DDQ-Mediated Oxidation, and TFA-Mediated Global

Deprotection

a

b

Isolated yields. NP = No desired product. ND = Not determined. Decomposition of 24n−24p under DDQ oxidation conditions was observed.

Decomposition of 26k occurred during the global deprotection under acidic conditions.

D

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Figure 1. Products 24q and 28−30 from the Heck and Sonogashira reactions of iodopyrrole 19 as well as azalamellarin χ 31.

oxidation to give 25k; however, global deprotection of 25k did

not furnish the desired product 26k (entry 11).

presence of DMAP did not furnish the corresponding C1-

acetate or C1-methyl ester. In addition to iodination using

NIS, the use of other succinimide-based halogenating agents

NCS and NBS furnished the C1−Cl and C1−Br pentacyclic

analogues 33 and 34 in 79% and 80% yields, respectively.

However, other N-hydroxy succinimide-derived reagents, 2,5-

dioxopyrrolidin-1-yl acetate and benzoate, in the presence or

absence of DMAP, could not aﬀord the corresponding C1-

methyl ketone and C1-phenyl ketone analogues 35 and 36.

Interestingly, while DDQ oxidation of 32 did not furnish the

corresponding aldehyde 37 containing C5C6, a three-step

process of Pinnick oxidation of the aldehyde to the

corresponding C1-carboxylic acid followed by methylation

and DDQ oxidation provided the corresponding C1-methyl

ester C5C6 analogue 38 in 39% overall yield. Unfortunately,

under various conditions, attempts to aﬀect global depro-

tection of 38 failed and gave only decarboxylated side

products.

We have also explored the use of iodopyrrole 19 for Heck

and Sonogashira cross-coupling reactions. However, despite

various attempts under diﬀerent reaction conditions, the

corresponding products 24q and 28−30 were either not

obtained or obtained in low yields (Figure 1); subsequent

steps of DDQ oxidation and global deprotection were not

performed. It should be noted that, under these conditions, 19

was completely consumed, and the reactions yielded 17, the

deiodinated pyrrole, as the major product. For the Heck

reaction with styrene, 24q was not obtained at all; the reaction

furnished only 17 in 82% yield. This observation suggested

that the ﬁrst step of oxidative addition of Pd(0) to iodopyrrole

occurred smoothly; however, the subsequent steps leading to

the products were troublesome. In addition, 24h was also

subjected to global deprotection of N- and O-benzyl-type

protecting groups without DDQ oxidation to yield the

corresponding azalamellarin χ 31 in 80% yield, which would

be employed for further biochemical studies (vide infra).

Interestingly, C1-H lactam 17 could also undergo direct C1

formylation using the Vilsmeier−Haack condition ((COCl)₂,

DMF, CH₂Cl₂)²⁰to furnish the corresponding pyrrole

aldehyde 32 in a moderate 48% yield (Scheme 6). It should

be noted that such direct formylation could not be aﬀected

when POCl₃was employed instead of oxalyl chloride; when

N,N-dimethylacetamide (DMA) was used, no corresponding

ketone was obtained. Other Friedel−Crafts-type acylation of

17 using acetic anhydride or methyl chloroformate in the

Some of these C1 derivatives, 22, 26a, 26e, 26g, 26h, 26i,

26l, and 31, were then chosen for further evaluations of their

biological activities.

Assessment of Cytotoxicity of Some Selected

Azalamellarins. Some novel azalamellarins were prepared

for the ﬁrst time via our modular synthetic method featuring

the late-stage functionalization at C1. Several previous

investigations have reported that derivatives of natural as

well as unnatural lamellarins could eﬃciently suppress the

viability of human cancer cells.^7d−fIn addition, the lactone-to-

lactam modiﬁcation was found to enhance several aspects of

the physicochemical properties of the compounds, thus

promoting cytotoxicity.^7e,fIn this current study, we, therefore,

determined whether some of these selected azalamellarin

analogues, 22, 26a, 26e, 26g, 26h, 26i, 26l, and 31, could

convey cytotoxicity toward HeLa cervical cancer cells. To

answer this, the viability of HeLa cells cultured in titrated

concentrations of azalamellarins was evaluated through crystal

violet staining. The data were then plotted and analyzed for

IC₅₀. Lamellarin D (LamD; 22), a leading compound among

the lamellarin analogues, exhibited IC₅₀at 2.84 μM (Figure 2,

panel A); this was consistent with the results obtained earlier,

which reported that 22 was cytotoxic against various cancer

cell lines.^7f,13aLikewise, the newly synthesized azalamellarins

from this study could eﬀectively limit the growth of HeLa cells

with the IC₅₀values ranging in submicromolar levels (0.442

μM for 26a; 0.501 μM for 26e; 0.473 μM for 26i; and 0.794

μM for 26l; Figure 2, panels B, C, F, and G, respectively).

These values were comparable to those of azalamellarins D

(26g, 0.383 μM) and N (26h, 0.317 μM) as shown in Figure 2,

panels D and E, respectively. When comparing these IC₅₀

values, all azalamellarins (0.317−0.794 μM) were found to be

approximately 3- to 9-fold more potent than 22 (2.84 μM).

Scheme 6. Direct Functionalization of C1-H Lactam 17

E

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Figure 2. Assessments of biological activities of newly synthesized lamellarins. Panels A−H: cytotoxicity of newly synthesized lamellarins/

azalamellarins comparing to LamD (22), azalamellarin D (26g), and azalamellarin N (26h). Colony formation of HeLa cancer cells treated with

the titrated lamellarins/azalamellarins for 18 h was determined by crystal violet staining. The viable stained colonies were dried and eluted for

OD₅₉₀measurement. The absorbance data were normalized and plotted into survival curves, calculated for IC₅₀and curve-ﬁtting R². In each

evaluation, the experiments were performed at least in triplicate. Error bars represent the standard deviation (n = 3). Panel I: impact of the newly

synthesized lamellarins on induction of apoptosis. HeLa cells were treated with the compounds at 2.5 μM for 8 h before collecting for cell pellets.

The cells were then determined for total protein and prepared for immunoblotting analysis with antibodies for apoptotic caspases (cCasp-3 and

cCasp-7), the enzymes activated during apoptosis, and their target, cPARP (p19 = 19 kDa cleaved form of caspase-3 (cCasp-3); p18 = 18 kDa

cCasp-7; p89 = 89 kDa cleaved poly(ADP-ribose) polymerase (cPARP)). The immunoblot data were recorded and analyzed for band densities.

The image shows representative results from two diﬀerent individual experiments.

F

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Interestingly, compound 31, azalamellarin χ, the lactam-

containing analogue of Lamχ, showed IC₅₀at 2.232 μM

(Figure 2, panel H), which was similar to the IC₅₀value

exhibited by 22. This was rather unusual because from their

structures, while almost identical to 22, both Lamχ and

azalamellarin χ possess a C5−C6 single bond in place of the

C5−C6 double bond in the D-ring of 22, which was reportedly

found to confer planarity deemed critical for cytotoxicity

against cancer cells.^7cTherefore, a lactone-to-lactam mod-

iﬁcation apparently could provide an enhancement on the

cytotoxicity of the analogues equivalent to the C5−C6 single

bond vs C5−C6 double bond in the D-ring.

The reaction sequence of Suzuki−Miyaura cross-coupling of

19, DDQ oxidation, and global deprotection proved to be

feasible to furnish lamellarins/azalamellarins in moderate to

good overall yields. On the other hand, while the C1-

formylated pyrrole 32 could be obtained from the direct C1-H

functionalization, its subsequent transformations failed to

furnish any azalamellarin. Upon evaluating their cytotoxicity

against HeLa cancer cells and investigating the eﬀects that

these new lamellarins/azalamellarins may exert on the

apoptosis by assessing the levels of apoptogenic protein

markers, the lactone-to-lactam modiﬁcation on the lamellarin

framework has clearly resulted in the perturbation of these

markers. Such modiﬁcation also superseded the need for the

C5−C6 oleﬁn for cytotoxicity as evident by comparing the

IC₅₀values and the levels of perturbation of the apoptogenic

protein markers for azalamellarin χ (31) with lamellarin χ

(Lamχ) and lamellarin D (22). Thus, the lactone-to-lactam

modiﬁcation increased cytotoxicity even for the analogue

containing the C5−C6 single bond. Because the exact

molecular mechanisms of lamellarins/azalamellarins are likely

to be multicellular events, further investigations are warranted

to elucidate the exact molecular targets and cellular processes

involved in their anticancer property; this is in progress in our

laboratory, and the results will be reported in due course.

The cytotoxicity of lamellarins was reportedly associated

with the ability to induce intrinsic apoptosis.^7b,13a,c,dHence,

this group of compounds has been proposed to be one of the

promising anticancer agents. We then observed whether our

new azalamellarins could potentiate acute activation of

apoptosis in cells by immunoblotting detection of apoptogenic

protein markers such as cleaved forms of cysteine proteases

(caspase-3 (cCasp-3, p19) and caspase-7 (cCasp-7, p18),

respectively) as well as an 89 kDa fragment of nuclear

Poly(ADP)ribose Polymerase (cPARP, p89) generated by

enzymatically active forms of cCasp-3 and -7. The HeLa cells

treated for 8 h with 22 showed more than 5-fold inductions of

cCasp-3, -7, and cPARP compared with DMSO-treated cells

(Figure 2, panel I: lane 2 vs lane 1). The treatment by 26g and

26h caused even stronger than 10-fold inductions of those

proteins (Figure 2, panel I: lanes 3 and 7); similar eﬀects were

also found in cells treated with 26a, 26e, 26i, 26l, and 31

(Figure 2, panel I: lanes 10, 11, 9, 8, and 5, respectively).

Notably, 31 could mediate a strong induction of apoptogenic

proteins better than 22 (Figure 2, panel I: lane 5 vs lane 2),

although their cytotoxicity IC₅₀values were virtually identical.

In the same experimental setting, the cells treated with Lamχ

showed no noticeable eﬀects on the accumulation of

apoptogenic proteins (Figure 2, panel I: lane 4). These data

implicated that even though lactone-to-lactam modiﬁcation of

Lamχ to 31 may not have improved activity on cell death, such

chemical modiﬁcation drastically promoted the activity of the

compound in apoptosis activation. Consistent with this idea,

26h-treated cells exhibited strong induction of apoptosis, but

cells treated by LamN, a lactone-containing isomer of 26h,

were unaﬀected by apoptotic induction (Figure 2, panel I:

lanes 6 vs 7). Hence, the data clearly show that the lactone-to-

lactam modiﬁcation could enhance cytotoxicity and the

biological activity of the lamellarins at the cellular level. In

addition, our azalemallarins 26a, 26e, 26i, and 26l, while

containing diﬀerent orthogonal rings at C1, all exhibited

comparable cytotoxicity and potency of apoptosis induction.

Further investigation on speciﬁc cellular events related to their

cytotoxicity may reveal a more speciﬁc biological role of the

orthogonal ring on the lamellarin framework.

EXPERIMENTAL SECTION

■

General Experimental Methods. Unless otherwise noted,

reactions were run in oven-dried round-bottomed ﬂasks. Tetrahy-

drofuran (THF) was distilled from sodium benzophenone ketyl or

puriﬁed by the solvent puriﬁcation system (PURE-SOLV, Innovative

Technology), while dichloromethane (CH₂Cl₂) was also puriﬁed by

the solvent puriﬁcation system (PURE-SOLV, Innovative Technol-

ogy) prior to use. All other compounds were used as received from

the suppliers. The crude reaction mixtures were concentrated under

reduced pressure by removing organic solvents on a rotary evaporator.

Column chromatography was performed using silica gel 60 ((i)

Merck, particle size 0.06−0.2 mm; 70−230 mesh ASTM or (ii)

Silicycle, SiliaFlash F60, particle size 40−63 μm; 230−400 mesh).

Analytical thin-layer chromatography (TLC) was performed with

silica gel 60 F₂₅₄aluminum sheets (Merck). All reactions under

microwave irradiation were performed using sealed reaction vessels

placed in a microwave synthesizer (CEM Microwave Technology,

UK; Discover and Explorer SP model), and the temperature of the

reactions was monitored by an external surface sensor. Chemical shifts

1

for H nuclear magnetic resonance (NMR) spectra were reported in

parts per million (ppm, δ) downﬁeld from tetramethylsilane. Splitting

patterns are described as singlet (s), doublet (d), triplet (t), quartet

(q), multiplet (m), broad (br), doublet of doublet (dd), doublet of

triplet (dt), and doublet of doublet of doublet (ddd). All ¹³C NMR

data were obtained with the use of broadband decoupling (¹³C{¹H})

and reported as proton-decoupled data. Chemical shifts of ¹⁹F NMR

spectra were reported in ppm on the δ scale from the peak of C₆F₆

(−164.9 ppm) as an internal reference. High-resolution (HRMS)

mass spectra were obtained using time-of-ﬂight (TOF) via the

atmospheric-pressure chemical ionization (APCI) or electrospray

ionization (ESI). Melting points were uncorrected.

General Procedure A: O-Benzylation. To a stirred solution of 10

or 14 (1.0 equiv) in ethanol (5 mL/mmol) were added potassium

carbonate (1.5 equiv) and benzyl bromide (1.1 equiv) at room

temperature. The mixture was heated to reﬂux by using an oil bath for

3 h. At that time, the reaction was cooled to room temperature, and

potassium carbonate was ﬁltered oﬀ. The resulting mixture was

concentrated under reduced pressure; water was added, and the

mixture was extracted with EtOAc (3 times). The combined organic

layers were washed once with water and brine, dried over anhydrous

Na₂SO₄, ﬁltered, and concentrated under reduced pressure to give the

CONCLUSION

■

In summary, modular synthesis of C1-modiﬁed azalamellarins

was successfully developed. Our hybrid strategy features both

the convergent and divergent nature of the approach in the

Michael-addition/ring closure (Mi-RC) Grob-type condensa-

tion reaction to form the pyrrole core and the late-stage C1

functionalization (via the intermediacy of the iodopyrrole 19),

respectively. Such late-stage C1 functionalization allows the

incorporation of groups that otherwise may not be compatible

with the reaction conditions required for the preceding steps.

G

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crude product mixture. Further puriﬁcation by crystallization in

EtOAc/hexane then furnished the desired product.

10I as a white solid (86.3 g, 0.36 mol, 90%). The physical and

spectroscopic data are in good agreement with those previously

reported.²¹

General Procedure B: C1−H Pyrrole Halogenation of the

Pentacycles Containing Lactone or Lactam. To a stirred solution

of C1-H pyrrole lactone 16 or lactam 17 (1.0 equiv) in 1,2-

dichloroethane (DCE; 20 mL/mmol) was added the corresponding

N-halosuccinimide (NXS; X = I, Br or Cl) (1.5 equiv) at room

temperature. The resulting mixture was stirred at room temperature

for 3 h. At that time, the reaction was quenched with water and

extracted with CH₂Cl₂. The combined organic layers were washed

with water and brine, dried over anhydrous Na₂SO₄, ﬁltered, and

concentrated under reduced pressure to give the crude product, which

was further puriﬁed by column chromatography on silica (40%

EtOAc/hexane) to furnish the desired product.

(E)-2-(Benzyloxy)-1-methoxy-4-(2-nitrovinyl)benzene (11). To a

solution of 10I (40.0 g 0.17 mol) in glacial acetic acid (500 mL) were

added ammonium acetate (50.9 g, 0.66 mol) and nitromethane (54.0

mL, 1.01 mol) at room temperature. The mixture was heated to reﬂux

by using an oil bath for 1 h. At that time, the reaction was cooled to

room temperature, at which the desired product crystallized. The

resulting solid was then ﬁltered and washed with an excess amount of

water and hexane to yield 11 as a yellow solid (35.3 g, 0.12 mol, 75%).

The physical and spectroscopic data are in good agreement with those

previously reported.²¹

General Procedure C: Suzuki Cross-Coupling Reaction. To a

stirred solution of the lactone 18 or lactam 19 (1.0 equiv) in a 1,4-

dioxane/water mixture (3:1 v/v; 40 mL/mmol) in a sealed tube were

added boronic acid or borate derivatives (2.0 equiv), cesium

carbonate (2.0 equiv), and Pd(PPh₃)₄(0.05 equiv). The mixture

was heated to 110 °C by using an oil bath for 16 h. At that time, the

reaction was quenched with water and extracted with EtOAc. The

combined organic layers were washed with water and brine, dried over

anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced pressure

to give the crude product, which was further puriﬁed by column

chromatography on silica (40% EtOAc/hexane) to furnish the desired

product.

4-(Benzyloxy)-3-methoxybenzaldehyde (14I1). Following the

general procedure, vanillin (60.0 g, 0.39 mol), K₂CO₃(82.0 g, 0.59

mol), and benzyl bromide (52.0 mL, 0.44 mol) were employed to

furnish 14I1 as a white solid (91.2 g, 0.38 mol, 95%). The physical

and spectroscopic data are in good agreement with those previously

reported.²¹

General Procedure D: DDQ Oxidation. To a stirred solution of

24a−24m (1.0 equiv) in 1,2-dichloroethane (20 mL/mmol) was

added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ; 1.5 equiv)

at room temperature. The mixture was stirred at room temperature

for 16 h. At that time, the reaction was quenched with water and

extracted with EtOAc. The combined organic layers were washed with

water and brine, dried over anhydrous Na₂SO₄, ﬁltered, and

concentrated under reduced pressure to give the crude product,

which was further puriﬁed by column chromatography on silica (50%

EtOAc/hexane) to furnish the desired product.

General Procedure E: Global Deprotection. To a stirred solution

of 21, 23, 25a−25m (1.0 equiv) in triﬂuoroacetic acid (25 mL/

mmol) was added thioanisole (2.5 mL/mmol) at room temperature.

The mixture was heated to 60 °C by using an oil bath, and stirring

continued for 24 h. At that time, the reaction was quenched with a

saturated NaHCO₃solution and extracted with EtOAc. The

combined organic layers were washed with water and brine, dried

over anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced

pressure to give the crude product, which was further puriﬁed by

HPLC (reverse-phase C18 column: 250 mm × 21.2 mm, 5 μm

particle size; Luna) using 50% aqueous MeOH/i-PrOH as the eluting

solvent system with a ﬂow rate of 9 mL/min and the UV detector set

at 210, 254, and 366 nm.

General Procedure F: Sonogashira Cross-Coupling Reaction. To

a stirred solution of the lactam 19 (1.0 equiv) in triethylamine/DMF

(5:1 v/v; 15 mL/mmol), Pd(PPh₃)₄(0.05 equiv), and copper(I)

iodide (0.1 equiv) in a sealed tube, which was then degassed for 15

min at room temperature, were added acetylene derivatives (1.5

equiv). The mixture was heated to 60 °C by using an oil bath, and

stirring continued for 18 h. The reaction was quenched with a

saturated NH₄Cl solution and extracted with EtOAc. The combined

organic layers were washed with water and brine, dried over

anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced pressure

to give the crude product, which was further puriﬁed by column

chromatography on silica (30% EtOAc/hexane) to furnish the desired

product.

2-Bromo-4-(benzyloxy)-5-methoxybenzaldehyde (14I2). To a

stirred solution of 14a (40.0 g 0.17 mol) in methanol (500 mL)

was added Br₂(12.7 mL 0.25 mol) dropwise at room temperature,

and the mixture was stirred for 3 h. The reaction was quenched with a

saturated Na₂S₂O₅solution, the mixture was evaporated under

reduced pressure, and the resulting mixture was extracted with

EtOAc. The combined organic layers were washed with water and

brine, dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to give the crude product, which was further puriﬁed

by crystallization in EtOAc/hexane to furnish 14b as a white solid

(45.4 g, 0.14 mol, 86%). The physical and spectroscopic data are in

good agreement with those previously reported.²¹

Ethyl (Z)-3-(4-(Benzyloxy)-2-bromo-5-methoxyphenyl)-2-nitroa-

crylate (13). To a stirred solution of 14I2 (45.0 g, 0.14 mol) in

toluene (400 mL) were added diethylamine hydrochloride salt (23.0

g, 0.21 mol) and ethyl nitroacetate (19.4 mL, 0.18 mol) at room

temperature. The mixture was heated to reﬂux by using an oil bath for

3 days with an azeotropic setup using the Dean−Stark apparatus. At

that time, the reaction was cooled to room temperature. The resulting

mixture was concentrated under reduced pressure and extracted with

EtOAc. The combined organic layers were washed with water and

brine, dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to give the crude product, which was further puriﬁed

by column chromatography on silica (20% EtOAc/hexane) to furnish

13 as a brown oil (50.1 g, 0.12 mol, 82%). Physical and spectroscopic

data are in good agreement with those previously reported.^7f

N-(3-(Benzyloxy)-4-methoxyphenethyl)-2-bromoacetamide

(11I). A solution of the nitrostyrene 11 (30.0 g, 0.11 mol) in THF

(200 mL) was added to a stirred slurry of lithium aluminum hydride

(16.0 g, 0.42 mol) in THF (100 mL) at 0 °C. The reaction was

allowed to warm up to room temperature, at which stirring continued

for 18 h. At that time, the reaction was quenched with water, and any

resulting ﬁne suspension was removed via ﬁltration. The reaction was

concentrated under reduced pressure to give the corresponding

3-(Benzyloxy)-4-methoxybenzaldehyde (10I). Following general

procedure A, isovanillin (60.0 g, 0.39 mol), K₂CO₃(82.0 g, 0.59 mol),

and benzyl bromide (52.0 mL, 0.44 mol) were employed to furnish

H

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arylethylamine product, which was used in the next step without

further puriﬁcation.

δ 161.5, 148.9, 148.3, 148.0, 147.4, 136.9, 136.5, 134.6, 132.5, 131.4,

128.5, 128.0, 127.9, 127.3, 127.2, 124.6, 121.2, 119.3, 117.6, 114.6,

114.3, 113.7, 107.4, 105.8, 71.3, 71.1, 59.7, 56.2, 56.1, 42.6, 28.4, 13.7.

HRMS (TOF) m/z: [M + H]⁺calcd for C₃₇H₃₅O₆N⁷⁹Br, 668.1642;

found, 668.1630. HRMS (TOF) m/z: [M + H]⁺calcd for

C₃₇H₃₅O₆N⁸¹Br, 670.1625; found, 670.1608.

To a stirred solution of the crude arylethylamine (0.11 mol) in

CH₂Cl₂(300 mL) were added bromoacetyl bromide (11.5 mL, 0.13

mol) and a solution of Na₂CO₃(27.9 g, 0.26 mol) in water (270 mL)

at room temperature. The reaction was stirred for 3 h. At that time,

the two phases were separated, and the aqueous phase was extracted

with CH₂Cl₂(3 × 150 mL). The combined organic layers were

washed with water (150 mL) and brine (150 mL), dried over

anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced pressure

to give the crude amide product, which was further puriﬁed by

column chromatography on silica (50% EtOAc/hexane) to furnish

11I as a white solid (34.6 g, 0.092 mol, 87%). Mp: 115.3−117.4 °C.

¹H NMR (300 MHz, CDCl₃): δ 7.43−7.26 (m, 5H), 6.82−6.71 (m,

8-(Benzyloxy)-2-(4-(benzyloxy)-2-bromo-5-methoxyphenyl)-9-

methoxy-N-(4-methoxybenzyl)-5,6-dihydropyrrolo[2,1-a]-

isoquinoline-3-carboxamide (20). To a stirred solution of the

pyrrole ester 15 (0.30 g, 0.45 mmol) in 1,4 dioxane (5 mL) were

added 4-methoxybenzylamine (0.30 mL, 2.25 mmol) and trimethy-

laluminum (2.0 M in toluene; 0.57 mL, 1.40 mmol) at room

temperature. The reaction vessel was then sealed, and the reaction

mixture was heated under microwave irradiation (5 min ramping time

to 165 °C at 300 W; 65 min holding time) with an external surface

sensor to monitor the reaction temperature. At that time, the reaction

was quenched with water (3 mL), and aluminum complex salt was

ﬁltered oﬀ. The resulting mixture was concentrated under reduced

pressure and extracted with EtOAc (3 × 5 mL). The combined

organic layers were washed with water (5 mL) and brine (5 mL),

dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to give the crude product, which was further puriﬁed

by column chromatography on silica (40% EtOAc/hexane) to furnish

the corresponding pyrrole amide 20 as a yellow foam (0.30 g, 0.39

4H), 5.09 (s, 2H), 3.93 (s, 2H), 3.82 (s, 3H), 3.42 (q, J = 6.8 Hz,

2H), 2.68 (t, J = 7.1 Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ

165.2, 148.4, 148.1, 136.9, 130.7, 128.4, 127.7, 127.2, 121.3, 114.6,

112.0, 70.9, 55.9, 41.2, 34.7, 29.1. HRMS (TOF) m/z: [M + H]⁺

calcd for C₁₈H₂₁O₃N⁷⁹Br, 378.0699; found, 378.0696. HRMS (TOF)

m/z: [M + H]⁺calcd for C₁₈H₂₁O₃N⁸¹Br, 380.0679; found, 380.0675.

2-((3-(Benzyloxy)-4-methoxyphenethyl)amino)-2-oxoethyl ace-

tate (12). To a stirred solution of amide 11I (30.0 g, 79.3 mmol)

in THF (240 mL) were added potassium carbonate (22.0 g, 159

mmol) and glacial acetic acid (9.10 mL, 159 mmol) at room

temperature. The mixture was heated to reﬂux by using an oil bath for

18 h. At that time, the reaction was cooled to room temperature, and

potassium carbonate was ﬁltered oﬀ. The resulting mixture was

concentrated under reduced pressure and extracted with EtOAc. The

combined organic layers were washed with water (50 mL) and brine

(50 mL), dried over anhydrous Na₂SO₄, ﬁltered, and concentrated

under reduced pressure to give the crude product, which was further

puriﬁed by column chromatography on silica (50% EtOAc/hexane) to

1

mmol, 86%). H NMR (300 MHz, CDCl₃): δ 7.48−7.25 (m, 10H),

7.04 (s, 2H), 6.94 (s, 1H), 6.91 (s, 1H), 6.81−6.73 (m, 4H), 6.35 (s,

1H), 5.62 (t, J = 5.5 Hz, 1H), 5.15 (s, 2H), 5.06 (s, 2H), 4.64 (t, J =

6.7 Hz, 2H), 4.28 (d, J = 5.4 Hz, 2H), 3.88 (s, 3H), 3.73 (s, 3H), 3.71

(s, 3H), 2.97 (t, J = 6.7 Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ

161.4, 158.7, 149.0, 148.8, 148.3, 147.6, 136.9, 136.2, 133.0, 129.9,

129.3, 128.8, 128.6, 128.5, 128.1, 127.8, 127.3, 127.2, 127.1, 124.5,

122.4, 121.4, 117.6, 114.7, 114.3, 113.7 (2C), 107.2, 105.0, 71.11,

71.09, 56.1, 56.0, 55.1, 42.9, 42.7, 28.5. HRMS (TOF) m/z: [M +

H]⁺calcd for C₄₃H₄₀O₆N₂⁷⁹Br, 759.2064; found, 759.2059; calcd for

C₄₃H₄₀O₆N₂⁸¹Br 761.2050; found, 761.2039.

1

furnish 12 as a brown oil (23.3 g, 65.1 mmol, 82%). H NMR (300

MHz, CDCl₃): δ 7.44−7.26 (m, 5H), 6.84−6.72 (m, 3H), 6.25 (br s,

1H), 5.11 (s, 2H), 4.47 (s, 2H), 3.84 (s, 3H), 3.46 (q, J = 6.8 Hz,

2H), 2.71 (t, J = 7.0 Hz, 2H), 2.06 (s, 3H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 169.2, 166.8, 148.3, 148.0, 136.8, 130.8, 128.3, 127.7,

127.2, 121.2, 114.7, 114.7, 111.9, 70.9, 62.7, 55.9, 40.1, 34.7, 20.4.

HRMS (TOF) m/z: [M + H]⁺calcd for C₂₀H₂₄O₅N, 358.1649;

found, 358.1642.

3,11-Bis(benzyloxy)-2,12-dimethoxy-8,9-dihydro-6H-chromeno-

[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one (16). To a stirred solution

of the pyrrole ester 15 (0.30 g, 0.45 mmol) in 1,4-dioxane (6 mL) was

added sodium amide (0.14 g, 3.59 mmol). The mixture was heated to

100 °C by using an oil bath for 18 h. The reaction was quenched with

water (5 mL), and the mixture was extracted with EtOAc (3 × 5 mL).

The combined organic layers were washed with water (5 mL) and

brine (5 mL), dried over anhydrous Na₂SO₄, ﬁltered, and

concentrated under reduced pressure to yield the corresponding

pyrrole carboxylic acid crude product, which was used directly in the

next step without further puriﬁcation.

Ethyl 8-(Benzyloxy)-2-(4-(benzyloxy)-2-bromo-5-methoxyphen-

yl)-9-methoxy-5,6-dihydropyrrolo[2,1-a]isoquinoline-3-carboxylate

(15). To a stirred solution of amide 12 (22.5 g, 63.0 mmol) in

anhydrous acetonitrile (150 mL) was added phosphorus oxychloride

(17.7 mL 189 mmol) at room temperature. The mixture was heated

to reﬂux by using an oil bath for 3 h. At that time, the reaction was

cooled to room temperature and basiﬁed with an aqueous Na₂CO₃

solution (30.0 g, 283 mmol in water (300 mL)). The resulting

mixture was extracted with EtOAc (3 × 200 mL). The combined

organic layers were washed with water (200 mL) and brine (200 mL),

dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to give the crude dihydroisoquinoline product

,which was used in the next step without further puriﬁcation.

To a stirred solution of the crude dihydroisoquinoline in anhydrous

acetonitrile (550 mL) were added sodium bicarbonate (5.30 g, 83.9

mmol) and nitrocinnamate 13 (18.3 g, 42.0 mmol) at room

temperature. The mixture was heated to reﬂux by using an oil bath

for 18 h. At that time, the reaction was cooled to room temperature,

and sodium bicarbonate was ﬁltered oﬀ. The resulting mixture was

concentration under reduced pressure and extracted with EtOAc (3 ×

100 mL). The combined organic layers were washed with water (200

mL) and brine (200 mL), dried over anhydrous Na₂SO₄, ﬁltered, and

concentrated under reduced pressure to give the crude product, which

was further puriﬁed by column chromatography on silica (30%

EtOAc/hexane) to furnish the desired pyrrole ester 15 as a yellow

To a stirred solution of the crude pyrrole carboxylic acid in DMF

(5 mL) were added copper(I) thiophene-2-carboxylate (CuTC; 4.30

mg, 0.023 mmol) and cesium carbonate (0.30 g, 0.91 mmol). The

reaction vessel was then sealed, and the reaction mixture was heated

under microwave irradiation (5 min ramping time to 150 °C at 300

W; 5 min holding time) with an external surface sensor to monitor the

reaction temperature. At that time, the reaction was quenched with a

saturated NH₄Cl solution (2 mL), and the residual copper salt was

ﬁltered oﬀ. The resulting mixture was concentrated under reduced

pressure and extracted with EtOAc (3 × 5 mL). The combined

organic layers were washed with water (5 mL) and brine (5 mL),

dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to provide the crude product, which was further

puriﬁed by column chromatography on silica (40% EtOAc/hexane),

to furnish the desired C1-H pyrrole lactone 16 as a brown solid (202

1

mg, 0.36 mmol, 80%). Mp: 213.5−214.7 °C. H NMR (400 MHz,

CDCl₃): δ 7.47−7.26 (m, 10H), 7.20 (s, 1H),7.18 (s, 1H),6.91 (s,

1H), 6.79 (s, 1H), 6.78 (m, 1H), 5.19 (s, 2H), 5.17 (s, 2H), 4.66 (t, J

= 6.9 Hz, 2H), 3.99 (s, 3H), 3.98 (s, 3H), 3.02 (t, J = 6.9 Hz, 2H).

¹³C{¹H} NMR (100 MHz, CDCl₃): δ 155.4, 149.02, 148.99, 148.3,

146.7, 145.8, 140.0, 136.6, 136.3, 131.0, 128.6, 128.1, 128.0, 127.3,

127.2, 125.6, 120.3, 115.0, 113.6, 110.4, 108.0, 104.6, 102.9, 95.4,

71.05, 71.03, 56.5, 56.3, 42.2, 28.2. HRMS (TOF) m/z: [M + H]⁺

calcd for C₃₅H₃₀O₆N, 560.2068; found, 560.2068.

1

foam (14.3 g, 21.4 mmol, 51%). H NMR (300 MHz, CDCl₃): δ

7.47−7.29 (m, 10H), 7.12 (s, 1H), 7.07 (s, 1H), 6.86 (s, 1H), 6.77 (s,

1H), 6.40 (s, 1H), 5.18 (s, 2H), 5.17 (s, 2H), 4.61 (t, J = 6.7 Hz, 2H),

4.04 (q, J = 6.0 Hz, 2H), 3.91 (s, 3H), 3.86 (s, 3H), 2.99 (t, J = 6.8

Hz, 2H), 0.91 (t, J = 7.1 Hz, 3H). ¹³C{¹H} NMR (75 MHz, CDCl₃):

I

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3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-8,9-

dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (17). To a

stirred solution of the pyrrole amide 20 (0.30 g, 0.40 mmol) in DMF

(5 mL) were added copper(I) thiophene-2-carboxylate (CuTC; 3.80

mg, 0.002 mmol) and cesium carbonate (0.26 g, 0.80 mmol). The

reaction vessel was then sealed, and the reaction mixture was heated

under microwave irradiation (5 min ramping time to 150 °C at 300

W; 5 min holding time) with an external surface sensor to monitor the

reaction temperature. At that time, the reaction was quenched with a

saturated NH₄Cl solution (2 mL), and the residual copper salt was

ﬁltered oﬀ. The resulting mixture was concentrated under reduced

pressure and extracted with EtOAc (3 × 5 mL). The combined

organic layers were washed with water (5 mL) and brine (5 mL),

dried over anhydrous Na₂SO₄, ﬁltered, and concentrated under

reduced pressure to provide the crude product, which was further

puriﬁed by column chromatography on silica (40% EtOAc/hexane) to

furnish the C1-H pyrrole lactam 17 as a white solid (0.24 g, 0.36

(m, 4H), 6.96 (d, J = 7.5 Hz, 1H), 6.94 (s, 1H), 6.72 (s, 1H), 5.31 (s,

2H), 5.24 (s, 2H), 5.18 (s, 2H), 3.90 (s, 3H), 3.36 (s, 3H), 3.36 (s,

3H). ¹³C{¹H} NMR (100 MHz, CDCl₃): δ 155.5, 150.5, 149.6, 149.2,

148.5, 147.9, 147.8, 146.4, 146.0, 136.9, 136.3, 136.2, 134.3, 129.3,

128.72, 128.69, 128.67, 128.12, 128.06, 127.3, 127.2, 127.0, 124.6,

123.9, 123.2, 119.3, 114.9, 114.6, 112.4, 111.0, 110.3, 109.5, 107.9,

105.5, 105.4, 102.7, 70.94, 70.88, 70.8, 56.3, 55.5, 55.2. HRMS (TOF)

m/z: [M + H]⁺calcd for C₄₉H₄₀O₈N, 770.2748; found, 770.2742.

These physical and spectroscopic data are in good agreement with

those previously reported.^7f

3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-dime-

thoxy-6H-chromeno[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one (22;

lamellarin D). Following general procedure E, compound 21 (21.0

mg, 0.027 mmol) gave the product, which was puriﬁed by a reverse-

phase HPLC column equilibrated with 100% solvent A (50%

methanol in water) and 0% B (isopropanol) at a ﬂow rate of 9

mL/min. The eluting solvent system was programmed as follows: a

linear gradient from the starting solvent to 35% (v/v) B in 50 min; a

linear gradient increasing from 35% to 80% (v/v) B for 20 min,

holding for 10 min; increasing to 100% B in 5 min, holding for 10

min; and re-equilibrating at initial conditions for 45 min. Product 22

was obtained (11.2 mg, 0.022 mmol, 82%). The physical and

spectroscopic data are in good agreement with those previously

reported.^7f

1

mmol, 90%). Mp: 220.4−221.8 °C. H NMR (400 MHz, CDCl₃): δ

7.48−7.29 (m, 12H), 7.08 (s, 1H), 7.06 (s, 1H), 6.89 (s, 1H), 6.82−

6.78 (m, 4H), 5.58 (br s, 2H), 5.20 (s, 2H), 5.05 (s, 2H), 4.89 (t, J =

6.7 Hz, 2H), 4.00 (s, 6H), 3.77 (s, 3H), 3.04 (t, J = 6.6 Hz, 2H).

¹³C{¹H} NMR (100 MHz, CDCl₃): δ 158.6, 155.9, 149.0, 148.5,

147.6, 145.7, 138.0, 136.8, 136.7, 130.6, 129.3, 128.62, 128.56, 128.5,

128.0, 127.9, 127.6, 127.2, 127.1, 125.7, 121.2, 120.1, 114.2, 113.7,

112.1, 107.9, 105.6, 102.9, 94.6, 71.3, 71.1, 56.4, 56.3, 55.2, 45.1, 42.3,

28.6. HRMS (TOF) m/z: [M + H]⁺calcd for C₄₃H₃₉O₆N₂, 679.2803;

found, 679.2794.

3,11-Bis(benzyloxy)-14-iodo-2,12-dimethoxy-8,9-dihydro-6H-

chromeno[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one (18). Following

general procedure B, C1-H pyrrole lactone 16 (2.00 g, 3.57 mmol)

and N-iodosuccinimide (NIS; 1.21 g, 5.39 mmol) were employed to

furnish the corresponding C1 iodopyrrole lactone 18 as a brown solid

(1.64 g, 2.39 mmol, 67%). Mp: 238.6−239.4 °C. ¹H NMR (400

MHz,CDCl₃): δ 8.56 (s, 1H), 8.30 (s, 1H), 7.47−7.31 (m, 10H), 6.90

(s, 1H), 6.82 (s, 1H), 5.21 (s, 2H), 5.18 (s, 2H), 4.73 (t, J = 6.5 Hz,

2H), 4.02 (s, 3H), 4.01 (s, 3H), 2.95 (t, J = 6.6 Hz, 2H). ¹³C{¹H}

NMR (100 MHz, CDCl₃): δ 154.5, 148.8, 148.3, 147.9, 145.9, 145.7,

137.6, 136.6, 136.2, 129.4, 128.7, 128.08, 128.05, 127.8, 127.3, 127.2,

120.0, 115.9, 113.5, 110.4, 110.0, 103.8, 102.7, 71.0, 70.9, 56.4, 50.3,

42.6, 29.0. HRMS (TOF) m/z: [M + H]⁺calcd for C₃₅H₂₉O₆NI,

686.1034; found, 686.1033.

3,11-Bis(benzyloxy)-2,12-dimethoxy-14-phenyl-6H-chromeno-

[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one (18I). Following general

procedure C, C1-H pyrrole lactone 18 (102 mg, 0.148 mmol), phenyl

boronic acid (36.0 mg, 0.30 mmol), cesium carbonate (96.5 mg, 0.30

mmol), and Pd(PPh₃)₄(9 mg, 0.008 mmol) were employed to give

the desired C1-Ph pyrrole lactone, which was used in the DDQ

oxidation without further puriﬁcation.

Following general procedure D, the crude C1-Ph pyrrole lactone

and DDQ (0.05 g, 0.22 mmol) were employed to provide the crude

product, which was further puriﬁed by column chromatography on

silica (50% EtOAc/hexane) to furnish the pyrrole lactone 18I as a

white foam (0.070 g, 0.111 mmol, 75%). ¹H NMR (300 MHz,

CDCl₃): δ 9.19 (d, J = 7.3 Hz, 1H), 7.66−7.53 (m, 5H), 7.46−7.30

(m, 10H), 7.09 (s, 1H), 7.06 (s, 1H), 6.97 (d, J = 7.5 Hz, 1H), 6.94

(s, 1H), 6.62 (s, 1H), 5.24 (s, 2H), 5.18 (s, 2H), 3.41 (s, 3H), 3.39 (s,

3H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 155.5, 149.7, 149.2, 148.4,

146.4, 146.0, 136.3, 136.21, 136.18, 134.1, 131.9, 129.5, 129.2, 128.7,

128.4, 128.10, 128.07, 127.2, 124.6, 123.2, 119.3, 112.4, 111.3, 110.3,

109.5, 108.0, 105.5, 105.3, 102.8, 70.9, 70.8, 55.4, 55.1. HRMS (TOF)

m/z: [M + H]⁺calcd for C₄₁H₃₂O₆N, 634.2224; found, 634.2234.

3,11-Dihydroxy-2,12-dimethoxy-14-phenyl-6H-chromeno-

[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one (23). Following general

procedure E, compound 18I (22.0 mg, 0.035 mmol) gave the

product, which was puriﬁed by a reverse-phase HPLC column

equilibrated with 100% solvent A (50% methanol in water) and 0% B

(isopropanol) at a ﬂow rate of 9 mL/min. The eluting solvent system

was programmed as follows: a linear gradient from the starting solvent

to 45% (v/v) B in 50 min; a linear gradient increasing from 45% to

70% (v/v) B for 20 min, holding for 10 min; increasing to 100% B in

5 min, holding for 10 min; and re-equilibrating at initial conditions for

45 min. The product 23 was obtained as a yellow foam (11.3 mg,

0.025 mmol, 72%). ¹H NMR (600 MHz, DMSO-d₆): δ 9.99 (s, 1H),

9.89 (s, 1H), 9.02 (d, J = 7.4 Hz, 1H), 7.73−7.61 (m, 5H), 7.22 (d, J

= 7.4 Hz, 1H), 7.19 (s, 1H), 6.96 (s, 1H), 6.87 (s, 1H), 6.53 (s, 1H),

3.28 (s, 3H), 3.27 (s, 3H). ¹³C{¹H} NMR (150 MHz, DMSO-d₆): δ

154.4, 148.6, 148.4, 147.9, 146.3, 144.7, 135.4, 133.8, 131.5, 129.6,

128.7, 128.5, 124.7, 122.1, 117.4, 112.5, 111.7, 110.5, 108.2, 106.7,

3,11-Bis(benzyloxy)-14-iodo-2,12-dimethoxy-5-(4-methoxyben-

zyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (19).

Following general procedure B, C1-H pyrrole lactam 17 (5.00 g, 7.37

mmol) and N-iodosuccinimide (NIS; 2.49 g, 11.1 mmol) were

employed to furnish the corresponding C1 iodopyrrole lactam 19 as a

1

brown solid (5.02 g, 6.24 mmol, 85%). Mp: 253.8−263.4 °C. H

NMR (400 MHz, CDCl₃): δ 8.92 (s, 1H), 8.34 (s, 1H), 7.48−

7.28(m, 10H), 7.05(s, 1H), 7.03 (s, 1H), 6.83−6.78 (m, 4H), 5.38

(br s, 2H), 5.22 (s, 2H), 5.05 (s, 2H), 4.98 (t, J = 6.2 Hz, 2H), 4.04

(s, 3H), 4.03 (s, 3H), 3.77 (s, 3H), 2.95 (t, J = 6.5 Hz, 2H). ¹³C{¹H}

NMR (100 MHz, CDCl₃): δ 158.7, 155.2, 148.4, 147.8, 147.5, 144.6,

136.8, 136.6, 136.1, 130.8, 128.8, 128.7, 128.6, 128.3, 128.0, 127.9,

127.5, 127.2, 127.1, 126.3, 120.8, 120.7, 114.2, 113.5, 112.2, 110.4,

104.7, 102.7, 71.1, 71.0, 56.44, 56.38, 55.3, 49.8, 45.4, 42.6, 29.5.

HRMS (TOF) m/z: [M + H]⁺calcd for C₄₃H₃₈O₆N₂I, 805.1769;

found, 805.1755.

3,11-Bis(benzyloxy)-14-(4-(benzyloxy)-3-methoxyphenyl)-2,12-

dimethoxy-6H-chromeno[4′,3′:4,5]pyrrolo[2,1-a]isoquinolin-6-one

(21). Following general procedure C, C1 iodopyrrole lactone 18 (0.11

g, 0.16 mmol), 4-benzyloxy-3-methoxyphenyl boronic acid (0.083 g,

0.32 mmol), cesium carbonate (0.11 g, 0.32 mmol), and Pd(PPh₃)₄

(9.0 mg, 0.008 mmol) were employed to furnish the corresponding

C1 arylated pyrrole lactone, which was used in the subsequent step

without further puriﬁcation.

Following general procedure D, the C1 arylated pyrrole lactone

obtained from the previous step and DDQ (0.055 g, 0.24 mmol) were

employed to furnish the corresponding O-benzylated lamellarin D 21

1

as a brown solid (0.079 g, 0.102 mmol, 64%). H NMR (400 MHz,

CDCl₃): δ 9.18 (d, J = 7.3 Hz, 1H), 7.50−7.30 (m, 16H), 7.14−7.09

J

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Article

105.5, 105.2, 103.8, 55.0, 54.5. HRMS (TOF) m/z: [M + H]⁺calcd

for C₂₇H₂₀O₆N, 454.1285; found, 454.1289.

3,11-Bis(benzyloxy)-14-(4-(benzyloxy)phenyl)-2,12-dimethoxy-5-

(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (24e). Following general procedure C, iodopyr-

role lactam 19 (100 mg, 0.124 mmol), 4-benzyloxy phenyl boronic

acid (57.0 mg, 0.25 mmol), cesium carbonate (81.0 mg, 0.25 mmol),

and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were employed to furnish 24e

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

phenyl-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(24a). Following general procedure C, iodopyrrole lactam 19 (100

mg, 0.124 mmol), phenyl boronic acid (31.0 mg, 0.25 mmol), cesium

carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.20 mg, 0.006

mmol) were employed to furnish 24a as a white solid (67.6 mg, 0.090

1

as a pale yellow sticky oil (98.3 mg, 0.114 mmol, 92%). H NMR

(300 MHz, CDCl₃): δ 7.46−7.24 (m, 17H), 7.18 (s, 1H), 7.15 (s,

1H), 7.08 (s, 1H),7.05 (s, 1H), 6.88 (s, 1H), 6.80−6.74 (m, 4H), 6.66

(s, 1H), 5.38 (br s, 2H), 5.17 (s, 2H), 5.13 (s, 2H), 4.98−4.95 (m,

2H), 3.75 (s, 3H), 3.33 (s, 3H), 3.29 (s, 3H), 3.02 (t, J = 6.5 Hz, 2H).

¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5, 158.2, 155.9, 147.8, 147.4,

146.7, 144.8, 136.8, 136.7, 133.8, 132.7, 130.5, 129.23, 129.19, 128.6,

128.5, 128.0, 127.9, 127.8, 127.5, 127.2, 127.13, 127.08, 127.0, 126.5,

125.6, 121.3, 118.8, 115.7, 114.1, 114.0, 113.4, 112.6, 109.0, 105.8,

102.6, 71.1, 70.9, 69.9, 55.2, 55.13, 55.06, 45.1, 42.4, 29.0. HRMS

(TOF) m/z: [M + H⁺] calcd for C₅₆H₄₉O₇N₂, 861.3534; found,

861.3513.

1

mmol, 72%). Mp: 213.6−215.4 °C. H NMR (300 MHz, CDCl₃): δ

7.58−7.24 (m, 15H), 7.09 (s, 1H), 7.06 (s, 1H), 6.82 (s, 1H), 6.80 (s,

1H), 6.77(s, 2H), 6.75 (s, 1H), 6.61 (s, 1H), 5.40 (br s, 2H), 5.13 (s,

2H), 5.01−4.96 (m, 4H), 3.76 (s, 3H), 3.33 (s, 3H), 3.29 (s, 3H)

3.04 (t, J = 6.6 Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5,

155.9, 147.9, 147.4, 146.7, 144.8, 137.2, 136.8, 136.6, 133.6, 131.6,

130.4, 129.3, 129.2, 128.6, 128.52, 128.46, 127.9, 127.8, 127.7, 127.5,

127.2, 127.1, 127.0, 126.5, 125.4, 121.2, 118.9, 114.5, 114.1, 113.3,

112.5, 109.0, 105.7, 102.6, 71.0, 70.9, 55.2, 55.02, 54.95, 45.1, 42.4,

28.9. HRMS (TOF) m/z: [M + H]⁺calcd for C₄₉H₄₃O₆N₂, 755.3116;

found, 755.3102.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-(4-

(triﬂuoromethoxy)phenyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (24f). Following general procedure C, iodopyr-

role lactam 19 (100 mg, 0.124 mmol), 4-triﬂuoromethyl phenyl

boronic acid (52.0 mg, 0.25 mmol), cesium carbonate (81.0 mg, 0.25

mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were employed to

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-(p-

tolyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(24b). Following general procedure C, iodopyrrole lactam 19 (100

mg, 0.124 mmol), p-tolylboronic acid (34.0 mg, 0.25 mmol), cesium

carbonate (81 mg, 0.25 mmol), and Pd(PPh₃)₄(7.20 mg, 0.006

mmol) were employed to furnish 24b as a white foam (86.1 mg, 0.112

1

furnish 24f as a colorless sticky oil (85.9 mg, 0.102 mmol, 82%). H

1

mmol, 90%). H NMR (300 MHz, CDCl₃): δ 7.46−7.27 (m, 14H),

NMR (300 MHz, CDCl₃): δ 7.65(s, 1H),7.63 (s, 1H), 7.47−7.27 (m,

12H), 7.08 (s, 1H), 7.06 (s, 1H), 6.81−6.77 (m, 4H), 6.71 (s, 1H),

6.51 (s, 1H), 5.39 (br s, 2H), 5.15 (s, 2H), 5.00−4.97 (m, 4H), 3.77

(s, 3H), 3.36 (s, 3H), 3.32 (s, 3H), 3.04 (t, J = 6.5 Hz, 2H). ¹³C{¹H}

NMR (75 MHz, CDCl₃): δ 158.6, 155.8, 148.8, 148.0, 147.7, 146.9,

145.0, 136.8, 136.6, 136.5, 133.8, 133.3, 130.6, 129.1, 128.6, 128.5,

127.94, 127.87, 127.6, 127.2, 127.0, 126.7, 125.4, 122.2, 120.8, 119.1,

114.2, 113.6, 112.7, 112.2, 108.8, 105.4, 102.8, 71.1, 71.0, 55.2, 54.9,

45.2, 42.4, 29.0. ¹⁹F NMR (282 MHz, CDCl₃): δ −61.3. HRMS

(TOF) m/z: [M + H]⁺calcd for C₅₀H₄₂O₇N₂F₃, 839.2939; found,

839.2927.

7.08 (s, 1H), 7.06 (s, 1H), 6.86 (s, 1H), 6.80−6.75 (m, 4H), 6.65 (s,

1H), 5.39 (br s, 2H), 5.14 (s, 2H), 5.00−4.96 (m, 3H), 3.77 (s, 3H),

3.36 (s, 3H), 3.32 (s, 3H), 3.03 (t, J = 6.6 Hz, 2H), 2.44 (s, 3H).

¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5, 156.0, 147.8, 147.4, 146.7,

144.8, 137.4, 136.9, 136.7, 133.9, 133.7, 131.5, 130.5, 129.9, 129.2,

128.6, 128.5, 127.9, 127.8, 127.6, 127.2, 127.0, 126.5, 125.6, 121.3,

118.9, 114.5, 114.1, 113.3, 112.6, 109.1, 105.9, 102.6, 71.1, 70.9, 55.2,

55.1, 55.0, 45.2, 42.4, 29.0, 21.2. HRMS (TOF) m/z: [M + H]⁺calcd

for C₅₀H₄₅O₆N₂, 769.3272; found, 769.3250.

3,11-Bis(benzyloxy)-14-(4-ﬂuorophenyl)-2,12-dimethoxy-5-(4-

methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (24c). Following general procedure C, iodopyrrole lactam

19 (100 mg, 0.124 mmol), 4-ﬂuorophenylboronic acid (35.0 mg, 0.25

mmol), cesium carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2

mg, 0.006 mmol) were employed to furnish 24c as a yellow foam

(81.7 mg, 0.106 mmol, 85%). ¹H NMR (300 MHz, CDCl₃): δ 7.58−

7.53 (m, 2H), 7.44−7.25 (m, 12H), 7.08 (s, 1H),7.06 (s, 1H), 6.81−

6.77 (m, 5H), 6.56 (s, 1H), 5.39 (br s, 2H), 5.14 (s, 2H), 4.99−4.96

(m, 4H), 3.76 (s, 2H), 3.41 (s, 3H), 3.36 (s, 3H), 3.03 (t, J = 6.5 Hz,

2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 162.4 (d, J_CF= 248 Hz),

158.6, 155.8, 147.9, 147.9, 147.6, 146.9, 144.9, 136.8, 136.6, 133.8,

133.5, 133.4 (d, J_CF= 8 Hz), 133.1 (d, J_CF= 4 Hz), 130.6, 129.1,

128.6, 128.5, 127.9, 127.8, 127.6, 127.1, 127.0, 126.7, 125.5, 121.0,

119.0, 116.2 (d, J_CF= 21 Hz), 114.1, 113.5, 113.4, 113.1, 112.3, 108.9,

105.6, 102.7, 71.1, 70.9, 55.2, 55.14, 55.07, 45.2, 42.4, 29.0. ¹⁹F NMR

(282 MHz, CDCl₃): δ −117.2. HRMS (TOF) m/z: [M + H]⁺calcd

for C₄₉H₄₂O₆N₂F, 773.3021; found, 773.3010.

3,11-Bis(benzyloxy)-14-(4-(benzyloxy)-3-methoxyphenyl)-2,12-

dimethoxy-5-(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino-

[3,2-c]quinolin-6(5H)-one (24g). Following general procedure C,

iodopyrrole lactam 19 (100 mg, 0.124 mmol), 4-benzyloxy-3-

methoxyphenyl boronic acid (64.1 mg, 0.25 mmol), cesium carbonate

(81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were

employed to furnish 24g as a brown solid (91.1 mg, 0.102 mmol,

1

82%). H NMR (300 MHz, CDCl₃): δ 7.48−7.24 (m, 15H), 7.08−

7.06 (m, 5H), 6.88 (s, 1H), 6.80−6.72 (m, 5H), 5.39 (br s, 2H), 5.26

(s, 2H), 5.14 (s, 2H), 5.06−4.99 (m, 3H), 4.95−4.86 (m, 1H), 3.87

(s, 3H), 3.76 (s, 3H), 3.32 (s, 3H), 3.29 (s, 3H), 3.03 (t, J = 6.1 Hz,

2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5, 155.9, 150.4, 147.9,

147.5, 147.4, 146.8, 144.8, 136.9, 136.8, 136.6, 133.7, 130.5, 129.8,

129.2, 128.6, 128.54, 128.48, 128.0, 127.9, 127.8, 127.6, 127.5, 127.1,

127.0, 126.9, 126.4, 125.6, 123.6, 121.2, 118.8, 114.7, 114.6, 114.1,

113.3, 112.5, 108.9, 105.8, 102.6, 71.0, 70.9, 70.8, 56.2, 55.19, 55.15,

55.1, 45.1, 42.4, 28.9. The physical and spectroscopic data are in good

agreement with those previously reported.^7f

3,11-Bis(benzyloxy)-14-(3-(benzyloxy)phenyl)-2,12-dimethoxy-5-

(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (24d). Following general procedure C, iodopyr-

role lactam 19 (100 mg, 0.124 mmol), 3-benzyloxy phenyl boronic

acid (57.0 mg, 0.25 mmol), cesium carbonate (81.0 mg, 0.25 mmol),

and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were employed to furnish 24d

3,11-Bis(benzyloxy)-14-(3-(benzyloxy)-4-methoxyphenyl)-2,12-

dimethoxy-5-(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino-

[3,2-c]quinolin-6(5H)-one (24h). Following general procedure C,

iodopyrrole lactone 19 (100 mg, 0.124 mmol), 3-benzyloxy-4-

methoxyphenyl boronic acid (64.1 mg, 0.25 mmol), cesium carbonate

(81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were

employed to furnish 24h as a brown solid (94.5 mg, 0.106 mmol,

1

as a yellow foam (93.7 mg, 0.109 mmol, 88%). H NMR (300 MHz,

CDCl₃): δ 7.49−7.23 (m, 18H), 7.09−7.05 (m, 3H), 6.89 (s, 1H),

6.80−6.75(m, 4H), 6.68 (s, 1H), 5.40 (br s, 2H), 5.14 (s, 2H), 5.10−

5.02 (m, 3H), 5.00 (s, 2H), 4.93−4.84 (m, 1H), 3.75 (s, 3H), 3.35 (s,

3H), 3.30 (s, 3H), 3.06−3.00 (m, 2H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 159.5, 158.5, 155.9, 147.9, 147.5, 146.7, 144.9, 138.5,

136.8, 136.6, 136.5, 133.6, 130.4, 130.3, 129.1, 128.6, 128.53, 128.51,

128.0, 127.9, 127.8, 127.5, 127.3, 127.1, 127.0, 126.4, 125.4, 124.0,

121.1, 118.8, 117.4, 114.6, 114.2, 114.1, 113.3, 112.4, 109.0, 105.8,

102.6, 71.0, 70.9, 69.9, 55.2, 55.1, 55.0, 45.1, 42.4, 28.9. HRMS

(TOF) m/z: [M + H]⁺calcd for C₅₆H₄₉O₇N₂, 861.3534; found,

861.3510.

1

85%). H NMR (300 MHz, CDCl₃): δ 7.45−7.21 (m, 15H), 7.15−

7.06 (m, 5H), 6.88 (s, 1H), 6.81−6.75 (m, 4H), 6.65 (s, 1H), 5.39

(br s, 2H), 5.15 (s, 2H), 5.12 (s, 2H), 5.04−4.87 (m, 4H), 3.94 (s,

3H), 3.76 (s, 3H), 3.37 (s, 2H), 3.31 (s, 3H), 3.02 (t, J = 6.6 Hz, 2H).

¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5, 155.9, 149.3, 148.9, 147.9,

147.5, 146.8, 144.9, 136.9, 136.7, 136.4, 133.8, 130.5, 129.3, 129.2,

128.6, 128.51, 128.45, 128.0, 127.9, 127.8, 127.6, 127.4, 127.2, 127.0,

126.5, 125.6, 124.2, 121.2, 118.8, 116.8, 114.14, 114.06, 113.3, 112.7,

112.5, 108.9, 105.8, 102.6, 71.1, 70.9, 56.4, 55.22, 55.19, 55.1, 45.2,

K

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Article

42.4, 29.0. The physical and spectroscopic data are in good agreement

with those previously reported.^7f

127.6, 127.5, 127.1, 127.0, 126.53, 126.5, 126.4, 125.5, 121.1, 119.0,

114.3, 114.1, 113.3, 112.5, 109.1, 105.8, 102.6, 71.0, 70.8, 55.2, 54.8,

54.7, 45.1, 42.4, 29.0. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₃H₄₅O₆N₂, 805.3272; found, 805.3256.

14-(Benzo[b]thiophen-2-yl)-3,11-bis(benzyloxy)-2,12-dime-

thoxy-5-(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-

c]quinolin-6(5H)-one (24m). Following general procedure C,

iodopyrrole lactam 19 (100 mg, 0.124 mmol), benzo[b]thien-2-

ylboronic acid (45.0 mg, 0.25 mmol), cesium carbonate (81.0 mg,

0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were employed to

furnish 24m as a colorless sticky foam (50.4 mg, 0.062 mmol, 50%).

¹H NMR (300 MHz, CDCl₃): δ 7.91−7.88 (m, 1H), 7.83−7.80 (m,

1H), 7.47 (s, 1H), 7.43−7.27 (m, 13H), 7.08 (s, 1H), 7.06 (s, 1H),

6.95 (s, 1H), 6.81−6.76 (m, 4H), 5.40 (br s, 2H), 5.15 (s, 2H), 4.99

(br s, 4H), 3.77 (s, 3H), 3.17 (s, 3H), 3.12 (s, 3H), 3.05 (t, J = 6.7

Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.6, 155.8, 148.1,

147.9, 147.1, 145.1, 141.1, 140.2, 138.9, 136.8, 136.6, 135.5, 130.7,

129.1, 128.6, 128.5, 127.93, 127.87, 127.6, 127.2, 127.0, 126.8, 126.1,

124.7, 123.5, 122.2, 120.6, 114.2, 113.3, 112.0, 108.9, 105.8, 102.6,

71.1, 70.9, 55.3, 54.93, 54.9, 45.2, 42.5, 29.7. HRMS (TOF) m/z: [M

+ H]⁺calcd for C₅₁H₄₃O₆N₂S, 811.2836; found, 811.2829.

4-(3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-6-

oxo-5,6,8,9-tetrahydrobenzo[7,8]indolizino[3,2-c]quinolin-14-yl)-

N-methylbenzenesulfonamide (24i). Following general procedure C,

iodopyrrole lactam 19 (100 mg, 0.124 mmol), 4-methylsulfonamido

phenyl boronic acid (54.0 mg, 0.25 mmol), cesium carbonate (81.0

mg, 0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were

employed to furnish 24i as a colorless solid (43.2 mg, 0.051 mmol,

41%). Mp: 119.5−121.2 °C. ¹H NMR (300 MHz, CDCl₃): δ 8.07 (d,

J = 8.4 Hz, 2H), 7.77 (d, J = 8.3 Hz, 2H), 7.40−7.24 (m, 11H), 7.08

(s, 1H), 7.05 (s, 1H), 6.80−6.77 (m,4H), 6.66 (s, 1H), 6.40 (s, 1H),

5.40 (br s, 2H), 5.13 (s, 2H), 5.01−4.96 (m, 3H), 4.92−4.86 (m,

1H), 3.75 (s, 3H), 3.35 (s, 3H), 3.30 (s, 3H), 3.04 (t, J = 6.6 Hz, 2H),

2.71 (d, J = 5.3 Hz, 3H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.6,

155.8, 148.0, 147.94, 147.90, 147.1, 145.0, 142.6, 138.7, 136.6, 136.4,

133.8, 132.7, 130.6, 128.9, 128.6, 128.5, 128.0, 127.9, 127.5, 127.1,

127.04, 127.01, 125.2, 120.5, 119.2, 114.2, 113.6, 112.4, 112.0, 109.1,

105.6, 102.8, 71.1, 70.9, 55.2, 55.14, 55.10, 45.2, 42.4, 29.0. HRMS

(TOF) m/z: [M + H]⁺calcd for C₅₀H₄₆O₈N₃S, 848.3000; found,

848.2991.

Methyl 4-(3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxy-

benzyl)-6-oxo-5,6,8,9-tetrahydrobenzo[7,8]indolizino[3,2-c]-

quinolin-14-yl)benzoate (24j). Following general procedure C,

iodopyrrole lactam 19 (100 mg, 0.124 mmol), 4-methoxy carbonyl

phenyl boronic acid (45.0 mg, 0.25 mmol), cesium carbonate (81.0

mg, 0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were

employed to furnish 24j as a pale brown foam (46.4 mg, 0.057 mmol,

46%). ¹H NMR (300 MHz,CDCl₃): δ 8.25 (d, J = 8.1 Hz, 2H), 7.69

(d, J = 8.1 Hz, 2H), 7.48−7.26 (m, 10H), 7.08 (s, 1H), 7.05 (s, 1H),

6.81−6.73 (m, 5H), 6.47 (s, 1H), 5.39 (br s, 2H), 5.15 (s, 2H), 4.99

(s, 2H), 4.89 (t, J = 6.2 Hz, 2H), 3.99 (s, 3H), 3.77 (s, 3H), 3.32 (s,

3H) 3.27 (s, 3H), 3.04 (t, J = 6.2 Hz, 2H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 166.7, 158.6, 155.8, 148.4, 148.0, 147.7, 146.9, 144.9,

142.6, 138.0, 136.7, 136.6, 133.7, 132.0, 130.6, 130.3, 129.4, 129.2,

129.0, 128.6, 128.54, 128.52, 127.93, 127.86, 127.6, 127.5, 127.2,

127.14, 127.1, 127.0, 126.8, 125.2, 120.7, 119.2, 114.2, 113.6, 113.5,

113.3, 112.2, 109.1, 107.8, 105.7, 102.7, 71.1, 70.9, 55.2, 55.1, 52.4,

45.2, 42.4, 29.0. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₁H₄₅O₈N₂, 813.3170; found, 813.3182.

3,11-Bis(benzyloxy)-14-(cyclohex-1-en-1-yl)-2,12-dimethoxy-5-

(4-methoxybenzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (24n). Following general procedure C, iodopyr-

role lactam 19 (100 mg, 0.124 mmol), 1-cyclohexenyl boronic acid

(32.0 mg, 0.25 mmol), cesium carbonate (81.0 mg, 0.25 mmol), and

Pd(PPh₃)₄(7.2 mg, 0.006 mmol) were employed to furnish 24n as a

1

pale yellow oil (67.0 mg, 0.088 mmol, 71%). H NMR (300 MHz,

CDCl₃): δ 7.90 (s, 1H), 7.73 (s, 1H), 7.48−7.25 (m, 10H), 7.08 (s,

1H), 7.05 (s, 1H), 6.81−6.77 (m, 4H), 6.15 (br s, 1H), 5.38 (br s,

2H), 5.22−5.14 (m, 3H), 5.03 (s, 2H), 4.72−4.63 (m, 1H), 3.95 (s,

3H), 3.94 (s, 3H), 3.76 (s, 3H), 3.09−2.89 (m, 1H), 2.41−2.34(m,

4H), 1.96−1.85 (m, 4H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5,

155.8, 148.3, 147.6, 146.8, 145.1, 136.9, 136.7, 134.2, 132.6, 130.5,

129.9, 129.2, 128.6, 128.5, 127.93, 127.86, 127.6, 127.2, 127.1, 126.7,

124.6, 121.9, 118.8, 116.7, 114.1, 113.5, 113.0, 108.6, 105.7, 102.8,

71.2, 71.0, 56.1, 55.2, 45.2, 42.2, 30.3, 29.1, 26.1, 23.5, 22.2. HRMS

(TOF) m/z: [M + H]⁺calcd for C₄₉H₄₇O₆N₂, 759.3429; found,

759.3419.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

vinyl-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(24o). Following general procedure C, iodopyrrole lactam 19 (100

mg, 0.124 mmol), potassium vinyltriﬂuoroborate (34.0 mg, 0.25

mmol), cesium carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2

mg, 0.006 mmol) were employed to furnish 24o as a colorless oil

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

(pyridin-4-yl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (24k). Following general procedure C, iodopyrrole lactam

19 (100 mg, 0.124 mmol), 4-pyridinylboronic acid (31.0 mg, 0.25

mmol), cesium carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2

mg, 0.006 mmol) were employed to furnish 24k as a brown solid

1

(36.0 mg, 0.051 mmol, 41%). H NMR (300 MHz, CDCl₃): δ 8.03

(53.5 mg, 0.071 mmol, 57%). Mp: 195.5−197.7 °C. H NMR (300

(s, 1H), 7.69 (s, 1H), 7.48−7.20 (m, 11H), 7.07 (s, 1H), 7.04 (s,

1H), 6.81−6.77 (m, 4H), 5.82−5.69 (m, 2H), 5.39 (br s, 2H), 5.19

(s, 2H), 5.03 (s, 2H), 4.91 (t, J = 6.4 Hz, 2H), 3.90−3.86 (m, 6H),

3.76 (s, 3H), 2.98 (t, J = 6.4 Hz, 2H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 158.5, 155.8, 148.1, 147.8, 147.0, 145.0, 144.9, 137.0,

136.8, 136.6, 136.5, 133.7, 132.6, 130.6, 129.1, 128.6, 128.5, 128.3,

127.92, 127.86, 127.6, 127.5, 127.21, 127.20 127.1, 124.8, 121.5,

119.1, 114.1, 113.5, 113.0, 112.2, 110.3, 106.9, 102.7, 71.1, 71.0, 56.2,

55.2, 45.1, 42.2, 29.2. HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₅H₄₁O₆N₂, 705.2959; found, 705.2955.

MHz,CDCl₃): δ 8.84−8.82 (m, 2H), 7.57 (d, J = 5.4 Hz, 2H), 7.44−

7.28 (m, 10H), 7.09 (s, 1H), 7.06 (s, 1H), 6.81−6.79 (m, 4H), 6.72

(s, 1H), 6.44 (s, 1H), 5.40 (br s, 2H), 5.15 (s, 2H), 5.00−4.96 (m,

4H), 3.77 (s, 3H), 3.38 (s, 3H), 3.32 (s, 3H), 3.04 (t, J = 6.5 Hz, 2H).

¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.6, 155.7, 150.7, 148.0, 147.9,

147.1, 146.4, 145.1, 136.7, 136.5, 133.6, 130.6, 129.0, 128.6, 128.5,

128.0, 127.9, 127.5, 127.2, 127.0, 126.9, 124.9, 120.4, 119.4, 114.2,

113.5, 111.9, 111.3, 108.9, 105.5, 102.8, 71.1, 70.9, 55.22, 55.18, 55.1,

45.2, 42.4, 28.9. HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₈H₄₂O₆N₃, 756.3068; found, 756.3061.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

methyl-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(24p). Following general procedure C, iodopyrrole lactam 19 (100

mg, 0.124 mmol), methylboronic acid (15.0 mg, 0.25 mmol), cesium

carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.2 mg, 0.006

mmol) were employed to furnish 24p as a brown sticky foam (52.5

mg, 0.076 mmol, 61%); ¹H NMR (300 MHz, CDCl₃): δ 7.74 (s, 1H),

7.49−7.25 (m, 11H), 7.07 (s. 1H), 7.05 (s, 1H), 6.87−6.77 (m, 4H),

5.39 (br s, 2H), 5.21 (s, 2H), 5.04 (s, 2H), 4.89 (t, J = 6.0 Hz, 2H),

3.99 (s, 3H), 3.98 (s, 3H), 3.76 (s, 2H), 2.95 (t, J = 6.0 Hz, 2H), 2.87

(s, 3H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.6, 155.8, 148.4,

147.7, 146.9, 145.2, 136.9, 136.7, 134.4, 130.7, 129.2, 129.2, 128.6,

128.5, 128.0, 127.94, 127.88, 127.6, 127.5, 127.3, 127.2, 127.1, 125.8,

121.9, 119.0, 114.2, 114.0, 113.7, 110.3, 107.9, 106.9, 103.0, 71.2,

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

(naphthalen-2-yl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (24l). Following general procedure C, iodopyrrole lactam

19 (100 mg, 0.124 mmol), 2-naphthylboronic acid (43.0 mg, 0.25

mmol), cesium carbonate (81.0 mg, 0.25 mmol), and Pd(PPh₃)₄(7.3

mg, 0.006 mmol) were employed to furnish 24l as a pale brown solid

1

(62.0 mg, 0.077 mmol, 62%). Mp: 185.6−187.3 °C. H NMR (300

MHz, CDCl₃): δ 8.07−8.03 (m, 2H), 7.92−7.82 (m, 2H), 7.70−7.67

(m, 1H), 7.55−7.48 (m, 2H), 7.40−7.23 (m, 10H), 7.10 (s, 1H), 7.07

(s, 1H), 6.81−6.75 (m, 5H), 6.55 (s, 1H), 5.41 (br s, 2H), 5.18−5.04

(m, 2H), 4.97−4.87 (m, 3H), 3.76 (s, 3H), 3.09−3.00 (m, 5H), 2.92

(s, 3H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.5, 155.9, 147.8,

147.5, 146.8, 144.8, 136.8, 136.6, 134.2, 133.84, 133.81, 132.5, 130.5,

130.4, 129.4, 129.1, 128.8, 128.6, 128.5, 128.4, 127.83, 127.77, 127.7,

L

https://doi.org/10.1021/acs.joc.1c01639

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

pubs.acs.org/joc

Article

71.1, 56.4, 55.2, 45.2, 41.9, 29.7, 13.5. HRMS (TOF) m/z: [M + H]⁺

calcd for C₄₄H₄₁O₆N₂, 693.2959; found, 693.2947.

7.5 Hz, 1H), 6.81−6.77 (m, 3H), 5.44 (br s, 2H), 5.21 (s, 4H), 5.01

(s, 2H), 3.75 (s, 3H), 3.36 (s, 3H), 3.34 (s, 3H). ¹³C{¹H} NMR (100

MHz, CDCl₃): δ 158.6, 158.4, 155.9, 149.1, 148.5, 147.6, 144.8,

136.8, 136.6, 136.5, 133.3, 132.5, 131.3, 129.5, 129.2, 128.7, 128.6,

128.5, 128.2, 128.1, 128.0, 127.8, 127.7, 127.6, 127.4, 127.2, 127.1,

127.0, 124.1, 123.8, 119.6, 115.9, 115.1, 114.2, 113.0, 112.0, 110.8,

110.0, 109.6, 106.5, 105.7, 102.4, 71.0, 70.7, 69.9, 55.2, 55.1, 55.0,

45.1. HRMS (TOF) m/z: [M + H]⁺calcd for C₅₆H₄₇O₇N₂, 859.3378;

found, 859.3352.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

phenylbenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (25a). Fol-

lowing general procedure D, compound 24a (55.0 mg, 0.073

mmol) and DDQ (25.0 mg, 0.11 mmol) were employed to furnish

compound 25a as a white solid (38.2 mg, 0.051 mmol, 70%). Mp:

218.5−219.3 °C. ¹H NMR (400 MHz, CDCl₃): δ 9.61 (d, J = 7.5 Hz,

1H), 7.66−7.25 (m, 15H), 7.10−7.04 (m, 4H), 6.90 (s, 1H), 6.85 (d,

J = 7.5 Hz, 1H), 6.82−6.78 (m, 3H), 5.47 (br, s, 2H), 5.22 (s, 2H),

5.01 (s, 2H), 3.76 (s, 3H), 3.37 (s, 3H), 3.34 (s, 3H). ¹³C{¹H} NMR

(100 MHz, CDCl₃): δ 158.6, 156.0, 149.2, 148.5, 147.6, 144.9, 137.6,

136.5, 136.5, 132.2, 131.3, 129.5, 129.2, 128.6, 128.5, 128.1, 128.0,

127.9, 127.6, 127.2, 127.0, 126.97, 124.1, 123.8, 119.5, 114.2, 113.1,

111.9, 110.9, 110.5, 109.7, 106.5, 105.7, 102.5, 77.3, 71.0, 70.7, 55.2,

55.03, 54.98, 45.1. HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₉H₄₁O₆N₂, 753.2959; found, 753.2961.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-(4-

(triﬂuoromethoxy)phenyl)benzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (25f). Following general procedure D, compound 24f

(54.0 mg, 0.064 mmol) and DDQ (22.0 mg, 0.097 mmol) were

employed to furnish compound 25f as a white solid (36.0 mg, 0.043

1

mmol, 67%). Mp: 195.3−196.8 °C. H NMR (300 MHz, CDCl₃): δ

9.62 (d, J = 7.4 Hz, 1H), 7.74−7.72 (m, 2H), 7.55−7.52 (m, 2H),

7.45−7.25 (m, 10H), 7.09−7.05 (m, 3H), 6.92 (s, 1H), 6.86 (d, J =

7.5 Hz, 1H), 6.83−6.76 (m, 4H), 5.45 (br s, 2H), 5.20 (s, 2H), 5.01

(s, 2H), 3.74 (s, 3H), 3.40 (s, 3H), 3.37 (s, 3H). ¹³C{¹H} NMR (75

MHz, CDCl₃): δ 158.6, 155.9, 149.3, 149.03, 149.0, 148.7, 147.8,

144.9, 136.9, 136.5, 136.4, 134.0, 132.3, 131.4, 129.0, 128.7, 128.6,

128.6, 128.1, 128.0, 127.9, 127.6, 127.2, 127.00, 126.96, 124.2, 123.7,

122.4, 122.2, 119.2, 114.2, 113.2, 111.6, 111.1, 109.8, 108.5, 106.1,

105.3, 102.6, 71.0, 70.7, 55.2, 54.8, 54.8, 45.1. ¹⁹F NMR (282 MHz,

CDCl₃): δ −61.3. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₀H₄₀O₇N₂F₃, 837.2782; found, 837.2783.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-(p-

tolyl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (25b). Follow-

ing general procedure D, compound 24b (53.0 mg, 0.069 mmol) and

DDQ (24.0 mg, 0.11 mmol) were employed to furnish compound

1

25b as a pale yellow foam (40.0 mg, 0.052 mmol, 76%). H NMR

(300 MHz, CDCl₃): δ 9.60 (d, J = 7.4 Hz, 1H), 7.56−7.28 (m, 14H),

7.10−7.07 (m, 4H), 6.95 (s, 1H), 6.86 (d, J = 7.5 Hz, 1H), 6.82−6.77

(m, 3H), 5.47 (br s, 2H), 5.24 (s, 2H), 5.02 (s, 2H), 3.76 (s, 3H),

3.41 (s, 3H), 3.38 (s, 3H), 2.48 (s, 3H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 158.6, 156.0, 149.2, 148.5, 147.6, 144.9, 137.8, 136.6,

136.5, 134.2, 132.4, 132.1, 131.4, 130.1, 129.2, 128.64, 128.56, 128.0,

127.9, 127.6, 127.23, 127.16, 127.0, 124.1, 123.8, 119.6, 114.2, 113.0,

112.1, 110.9, 110.6, 109.7, 106.6, 105.9, 102.5, 71.1, 70.8, 55.2, 55.03,

54.95, 45.1, 21.3. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₀H₄₃O₆N₂, 767.3116; found, 767.3105.

3,11-Bis(benzyloxy)-14-(4-(benzyloxy)-3-methoxyphenyl)-2,12-

dimethoxy-5-(4-methoxybenzyl)benzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (25g). Following general procedure D, com-

pound 24g (50 mg, 0.056 mmol) and DDQ (0.019 g, 0.084 mmol)

were employed to furnish 25g as a pale brown solid (40.0 mg, 0.045

1

mmol, 80%). H NMR (400 MHz, CDCl₃): δ 9.62 (d, J = 7.4 Hz,

1H), 7.50−7.29 (m, 14H), 7.16−7.07 (m, 7H), 7.00 (s, 1H), 6.87 (d,

J = 7.5 Hz, 1H), 6.83−6.78 (m, 3H), 5.47 (br s, 2H), 5.31 (s, 2H),

5.23 (s, 2H), 5.02 (s, 2H), 3.89 (s, 3H), 3.76 (s, 3H), 3.36 (s, 3H),

3.34 (s, 3H). ¹³C{¹H} NMR (100 MHz, CDCl₃): δ 158.6, 156.0,

150.6, 149.2, 148.5, 147.7, 147.6, 144.9, 137.0, 136.6, 136.5, 132.4,

131.4, 130.1, 129.2, 128.7, 128.64, 128.56, 128.1, 128.0, 127.9, 127.6,

127.2, 127.1, 127.02, 126.99, 124.1, 123.8, 119.5, 115.2, 114.8, 114.2,

113.0, 111.9, 110.8, 110.1, 109.6, 106.5, 105.7, 102.5, 71.0, 70.9, 70.8,

56.2, 55.24, 55.19, 55.1, 45.1. The physical and spectroscopic data are

in good agreement with those previously reported.^7f

3,11-Bis(benzyloxy)-14-(4-ﬂuorophenyl)-2,12-dimethoxy-5-(4-

methoxybenzyl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(25c). Following general procedure D, compound 24c (52.0 mg,

0.067 mmol) and DDQ (23.0 mg, 0.10 mmol) were employed to

furnish compound 25c as a pale yellow foam (37.3 mg, 0.048 mmol,

1

72%). H NMR (300 MHz, CDCl₃): δ 9.63 (d, J = 7.3 Hz, 1H),

7.67−7.63 (m, 2H), 7.46−7.25 (m, 13H), 7.10−7.07 (m, 2H), 6.99

(s, 1H), 6.88−6.78 (m, 5H), 5.47 (br s, 2H), 5.23 (s, 2H), 5.02 (s,

2H), 3.76 (s, 3H), 3.45 (s, 3H), 3.42 (s, 3H). ¹³C{¹H} NMR (75

MHz, CDCl₃): δ 161.5 (d, J_CF= 249 Hz), 155.9, 149.2, 148.6, 147.7,

144.9, 136.5, 136.4, 134.1 (d, J_CF= 8 Hz), 133.5 (d, J_CF= 4 Hz),

132.4, 131.4, 129.1, 128.64, 128.56, 128.0, 127.9, 127.6, 127.3, 127.2,

127.1, 127.0, 124.2, 123.8, 119.3, 116.4 (d, J_CF= 21 Hz), 114.2, 113.1,

111.8, 111.0, 109.7, 109.0, 106.3, 105.4, 71.0, 70.7, 55.2, 55.1, 55.0,

45.1. ¹⁹F NMR (282 MHz, CDCl₃): δ −116.7. HRMS (TOF) m/z:

[M + H]⁺calcd for C₄₉H₄₀O₆N₂F, 771.2865; found, 771.2857.

3,11-Bis(benzyloxy)-14-(3-(benzyloxy)phenyl)-2,12-dimethoxy-5-

(4-methoxybenzyl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(25d). Following general procedure D, compound 24d (51.0 mg,

0.059 mmol) and DDQ (20.2 mg, 0.089 mmol) were employed to

furnish compound 25d as a colorless sticky oil (37.1 mg, 0.043 mmol,

3,11-Bis(benzyloxy)-14-(3-(benzyloxy)-4-methoxyphenyl)-2,12-

dimethoxy-5-(4-methoxybenzyl)benzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (25h). Following general procedure D, com-

pound 24h (50.0 mg, 0.056 mmol) and DDQ (19.1 mg, 0.084 mmol)

were employed to furnish compound 25h as a brown solid (41.0 mg,

1

0.046 mmol, 82%). H NMR (400 MHz, CDCl₃): δ 9.63 (d, J = 7.4

Hz, 1H), 7.47−7.16 (m, 18H), 7.11−7.08 (m, 4H), 6.98 (s, 1H), 6.87

(d, J = 7.3 Hz, 1H), 6.84−6.79 (m,3H), 5.48 (br s, 2H), 5.25 (s, 2H),

5.13 (s, 2H), 5.03 (s, 2H), 3.98 (s, 3H), 3.77 (s, 3H), 3.40 (s, 3H),

3.38 (s, 3H). ¹³C{¹H} NMR (100 MHz, CDCl₃): δ 158.6, 156.0,

149.6, 149.2, 149.1, 148.5, 147.7, 144.9, 136.6, 136.5, 136.3, 132.5,

131.4, 129.6, 129.3, 128.7, 128.6, 128.5, 128.1, 128.0, 127.9, 127.6,

127.5, 127.2, 127.1, 127.0, 124.8, 124.1, 123.8, 119.6, 117.3, 114.2,

113.0, 112.9, 112.0, 110.9, 110.1, 109.7, 106.6, 105.7, 102.5, 71.1,

71.0, 70.8, 56.5, 55.3, 55.2, 55.1, 45.1. The physical and spectroscopic

data are in agreement with those previously reported.^7f

1

73%). H NMR (300 MHz, CDCl₃): δ 9.60 (d, J = 7.4 Hz, 1H),

7.44−7.22 (m, 18H), 7.14−7.07 (m, 18H), 7.02 (s, 1H). 6.97 (s, 1H),

6.84−6.76 (m, 4H), 5.46 (br s, 2H), 5.18 (s, 2H), 5.09 (s, 2H), 5.00

(s, 2H), 3.74 (s, 3H), 3.36 (s, 3H), 3.35 (s, 3H). ¹³C{1H} NMR (75

MHz, CDCl₃): δ 159.6, 158.5, 155.9, 149.1, 148.4, 147.6, 144.8,

138.8, 136.5, 136.4, 132.1, 131.3, 130.5, 129.1, 128.54, 128.52, 128.49,

128.0, 127.9, 127.8, 127.6, 127.4, 127.2, 127.0, 126.9, 124.5, 124.0,

123.6, 119.3, 117.9, 115.0, 114.1, 112.9, 111.8, 110.9, 110.2, 109.5,

106.5, 105.7, 102.3, 70.9, 70.6, 69.9, 55.2, 55.1, 55.0, 45.0. HRMS

(TOF) m/z: [M + H]⁺calcd for C₅₆H₄₇O₇N₂, 859.3378; found,

859.3363.

4-(3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-6-

oxo-5,6-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-14-yl)-N-meth-

ylbenzenesulfonamide (25i). Following general procedure D,

compound 24i (40.0 mg, 0.047 mmol) and DDQ (16.0 mg, 0.070

mmol) were employed to furnish 25i as a yellow foam (12.7 mg,

1

0.015 mmol, 32%). H NMR (400 MHz, CDCl₃): δ 9.67 (d, J = 7.4

Hz, 1H), 8.17 (d, J = 7.4 Hz, 2H), 7.88 (d, J = 7.4 Hz, 2H), 7.45−

7.28 (m, 10H), 7.10−7.09 (m, 3H), 6.92 (d, J = 7.4 Hz, 1H), 6.85−

6.79 (m, 4H), 6.72 (s, 1H), 5.48 (br s, 2H), 5.23 (s, 2H), 5.02 (s,

2H), 4.67 (q, J = 5.3 Hz, 1H), 3.76 (s, 3H), 3.39 (s, 3H), 3.36 (s,

3H), 2.77 (d, J = 5.0 Hz, 3H). ¹³C{¹H} NMR (100 MHz, CDCl₃): δ

158.7, 155.9, 149.4, 148.8, 148.0, 147.9, 144.9, 143.2, 139.3, 139.2,

136.4, 136.3, 133.4, 132.1, 131.6, 129.0, 128.7, 128.6, 128.1, 128.0,

3,11-Bis(benzyloxy)-14-(4-(benzyloxy)phenyl)-2,12-dimethoxy-5-

(4-methoxybenzyl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(25e). Following general procedure D, compound 24e (50.0 mg,

0.058 mmol) and DDQ (20.0 mg, 0.088 mmol) were employed to

furnish compound 25e as a yellow sticky oil (44.5 mg, 0.052 mmol,

89%). H NMR (400 MHz, CDCl₃): δ 9.60 (d, J = 7.4 Hz, 1H),

7.48−7.28 (m, 19H), 7.09−7.00 (m, 4H), 6.96 (s, 1H), 6.84 (d, J =

1

M

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127.6, 127.2, 127.0, 126.8, 124.4, 123.8, 118.9, 114.2, 113.5, 111.4,

111.3, 109.9, 108.2, 106.4, 105.4, 102.7, 71.1, 70.8, 55.2, 55.1, 55.0,

45.2, 29.1. HRMS (TOF) m/z: [M + H]⁺calcd for C₅₀H₄₄O₈N₃S,

846.2843; found, 846.2852.

3,11-Dihydroxy-2,12-dimethoxy-14-phenylbenzo[7,8]indolizino-

[3,2-c]quinolin-6(5H)-one (26a). Following general procedure E,

compound 25a (25.0 mg, 0.033 mmol) gave the product, which was

puriﬁed by a reverse-phase HPLC column equilibrated with 100%

solvent A (50% methanol in water) and 0% B (isopropanol) at a ﬂow

rate of 9 mL/min. The eluting solvent system was programmed as

follows: a linear gradient from the starting solvent to 40% (v/v) B in

45 min; a linear gradient increasing from 40% to 65% (v/v) B for 20

min, holding for 10 min; increasing to 100% B in 5 min, holding for

10 min; and re-equilibrating at initial conditions for 45 min. The

product 26a was obtained as a white solid (11.7 mg, 0.026 mmol,

78%). Mp: 239.5−240.0 °C. ¹H NMR (400 MHz, DMSO-d₆): δ

11.31 (s, 1H), 9.76 (br s, 1H), 9.51 (br s, 1H), 9.39 (d, J = 7.4 Hz,

1H), 7.73−7.59 (m, 5H), 7.14 (s, 1H), 7.04 (d, J = 7.4 Hz, 1H), 6.94

(s, 1H), 6.89 (s, 1H), 6.62 (s, 1H), 3.26 (s, 3H), 3.24 (s, 3H).

¹³C{¹H} NMR (100 MHz, DMSO-d₆): δ 155.4, 148.0, 147.4, 147.0,

Methyl 4-(3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxy-

benzyl)-6-oxo-5,6-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-14-

yl)benzoate (25j). Following general procedure D, compound 24j

(50.0 mg, 0.061 mmol) and DDQ (21.0 mg, 0.093 mmol) were

employed to furnish 25j as a yellow foam (33.4 mg, 0.041 mmol,

67%). ¹H NMR (300 MHz, CDCl₃): δ 9.65 (d, J = 7.4 Hz, 1H), 8.33

(d, J = 8.1 Hz, 2H), 7.79 (d, J = 8.1 Hz, 2H), 7.45−7.25 (m, 12H),

7.10−7.06 (m, 3H), 6.92 (s, 1H), 6.88 (d, J = 7.5 Hz, 1H), 6.83−6.78

(m, 6H), 5.46 (br s, 2H), 5.21 (s, 2H), 5.01 (s, 2H), 4.01 (s, 3H),

3.76 (s, 3H), 3.35 (s, 3H), 3.32 (s, 3H). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 166.6, 158.6, 155.9, 149.3, 148.7, 147.8, 144.9, 143.1,

136.5, 136.4, 132.6, 132.0, 131.4, 130.5, 129.8, 129.1, 128.6, 128.5,

128.0, 127.9, 127.6, 127.2, 127.0, 126.8, 124.2, 123.8, 119.1, 114.2,

113.3, 111.5, 111.1, 109.7, 109.1, 106.4, 105.5, 102.5, 71.0, 70.7,

55.22, 55.16, 55.1, 52.4, 45.1. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₁H₄₃O₈N₂, 811.3014; found, 811.3020.

143.4, 136.8, 131.8, 131.3, 131.0, 129.5, 128.1, 127.6, 123.9, 122.6,

117.6, 112.2, 111.6, 110.5, 109.7, 108.3, 105.5, 105.2, 102.3, 54.6,

54.4. HRMS (TOF) m/z: [M + H⁺] calcd for C₂₇H₂₁O₅N₂, 453.1445;

found, 453.1436.

3,11-Dihydroxy-2,12-dimethoxy-14-(p-tolyl)benzo[7,8]-

indolizino[3,2-c]quinolin-6(5H)-one (26b). Following general proce-

dure E, compound 25b (22.0 mg, 0.029 mmol) gave the product,

which was puriﬁed by a reverse-phase HPLC column equilibrated

with 100% solvent A (50% methanol in water) and 0% B

(isopropanol) at a ﬂow rate of 9 mL/min. The eluting solvent

system was programmed as follows: a linear gradient from the starting

solvent to 50% (v/v) B in 50 min; a linear gradient increasing from

50% to 65% (v/v) B for 25 min, holding for 10 min; increasing to

100% B in 5 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26b was obtained as a white foam

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

(pyridin-4-yl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (25k).

Following general procedure D, compound 24k (50.0 mg, 0.066

mmol) and DDQ (23.0 mg, 0.10 mmol) were employed to furnish

compound 25k as a brown sticky foam (15.9 mg, 0.021 mmol, 32%).

¹H NMR (300 MHz, CDCl₃): δ 9.68 (d, J = 7.4 Hz, 1H), 8.93−8.92

(m, 2H), 7.69−7.67 (m, 2H), 7.47−7.29 (m, 10H), 7.11−7.08 (m,

2H), 6.93 (d, J = 7.5 Hz, 1H), 6.90−6.77 (m, 5H), 5.49 (br s, 2H),

5.25 (s, 2H), 5.03 (s, 2H), 3.77 (s, 3H), 3.42 (s, 3H), 3.39 (s, 3H).

¹³C{¹H} NMR (75 MHz, CDCl₃): δ 158.7, 155.9, 149.5, 148.9, 147.9,

145.0, 136.4, 136.3, 131.5, 129.0, 128.7, 128.6, 128.1, 128.0, 127.6,

127.2, 127.2, 127.0, 126.5, 124.4, 123.8, 118.9, 114.2, 113.6, 111.32,

111.27, 109.9, 106.1, 105.3, 102.7, 71.1, 70.8, 55.25, 55.17, 55.1.

HRMS (TOF) m/z: [M + H]⁺calcd for C₄₈H₄₀O₆N₃, 754.2912;

found, 754.2897.

1

(11.0 mg, 0.024 mmol, 82%). H NMR (600 MHz, DMSO-d₆): δ

11.24 (s, 1H), 9.76 (s, 1H), 9.50 (s, 1H), 9.36 (d, J = 7.3 Hz, 1H),

7.52−7.47 (m, 4H), 7.12 (s, 1H), 7.01 (d, J = 7.5 Hz, 1H), 6.96 (s,

1H), 6.88 (s, 1H), 6.66 (s, 1H), 3.29 (s, 3H), 3.27 (s, 3H), 2.45 (s,

3H). ¹³C{¹H} NMR (150 MHz, DMSO-d₆): δ 155.5, 148.1, 147.5,

147.1, 143.5, 137.6, 133.6, 131.6, 131.4, 131.3, 130.1, 127.8, 124.0,

122.7, 117.8, 112.3, 111.7, 110.6, 109.8, 108.6, 105.9, 105.5, 102.5,

54.9, 54.5, 20.9. HRMS (TOF) m/z: [M + H]⁺calcd for

C₂₈H₂₃O₅N₂, 467.1601; found, 467.1607.

14-(4-Fluorophenyl)-3,11-dihydroxy-2,12-dimethoxybenzo[7,8]-

indolizino[3,2-c]quinolin-6(5H)-one (26c). Following general proce-

dure E, compound 25c (25.0 mg, 0.0324 mmol) gave the product,

which was puriﬁed by a reverse-phase HPLC column equilibrated

with 100% solvent A (50% methanol in water) and 0% B

(isopropanol) at a ﬂow rate of 9 mL/min. The eluting solvent

system was programmed as follows: a linear gradient from the starting

solvent to 44% (v/v) B in 49 min; a linear gradient increasing from

44% to 60% (v/v) B for 40 min, holding for 5 min; increasing to

100% B in 5 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26c was obtained as a yellow

sticky oil (9.2 mg, 0.0194 mmol, 60%). ¹H NMR (300 MHz, DMSO-

d₆): δ 11.32 (s, 1H), 9.81 (s, 2H), 9.57 (s, 1H), 9.39 (d, J = 7.4 Hz,

1H), 7.70−7.65 (m, 2H), 7.57−7.51 (m, 2H), 7.15 (s, 1H), 7.04 (d, J

= 7.5 Hz, 1H), 6.90 (s, 2H), 6.58 (s, 1H), 3.34 (s, 3H), 3.31 (s, 3H).

¹³C{¹H} NMR (75 MHz, DMSO-d₆): δ 162.2 (d, J_CF= 246 Hz),

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-

14-(naphthalen-2-yl)benzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (25l). Following general procedure D, compound 24l

(52.0 mg, 0.068 mmol) and DDQ (24.0 mg, 0.11 mmol) were

employed to furnish compound 25l as a yellow sticky foam (33 mg,

1

0.041 mmol, 60%). H NMR (400 MHz,CDCl₃): δ 9.65 (d, J = 7.5

Hz, 1H), 8.18−8.13 (m, 2H), 7.96 (d, J = 7.2 Hz, 1H), 7.89 (d, J =

8.6 Hz, 1H), 7.77 (d, J = 9.4 Hz, 1H), 7.59−7.55(m, 2H), 7.44−7.28

(m, 10H), 7.11−7.07 (m, 3H), 7.00 (s, 1H), 6.89 (d, J = 7.5 Hz, 1H),

6.87 (s, 1H), 6.82−6.78 (m, 3H), 5.48 (br s, 2H), 5.22 (s, 2H), 5.00

(s, 2H), 3.77 (s, 3H), 2.99 (s, 3H), 2.97 (s, 3H). ¹³C{¹H} NMR (100

MHz, CDCl₃): δ 158.6, 156.0, 149.2, 148.5, 147.6, 144.8, 136.5,

136.5, 134.7, 133.9, 132.8, 132.5, 131.4, 131.0, 129.9, 129.2, 129.1,

128.7, 128.6, 128.5, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.3,

127.19, 127.16, 127.1, 127.0, 126.7, 126.6, 124.2, 123.8, 119.5, 114.2,

113.2, 111.9, 111.0, 110.3, 109.7, 106.5, 105.8, 102.5, 71.0, 70.7, 55.2,

54.82, 54.75, 45.1. HRMS (TOF) m/z: [M + Na]⁺calcd for

C₅₃H₄₂O₆N₂Na, 825.2935; found, 825.2910.

14-(Benzo[b]thiophen-2-yl)-3,11-bis(benzyloxy)-2,12-dime-

thoxy-5-(4-methoxybenzyl)benzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (25m). Following general procedure D, compound 24m

(50.4 mg, 0.061 mmol) and DDQ (0.022, 0.097 mmol) were

employed to furnish compound 25m as a colorless sticky foam (23.0

mg, 0.028 mmol, 46%). ¹H NMR (300 MHz, CDCl₃): δ 9.64 (d, J =

7.4 Hz, 1H), 7.96−7.85 (m, 2H), 7.57 (s, 1H), 7.46−7.26 (m, 13H),

7.18 (s, 1H), 7.11−7.08 (m, 3H), 6.92 (d, J = 7.5 Hz, 1H), 6.83−6.79

(m, 3H), 5.47 (br s, 2H), 5.24 (s, 2H), 5.02 (s, 2H), 3.77 (s, 3H),

3.19 (s, 3H), 3.17 (s, 3H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ

158.6, 155.9, 149.5, 148.9, 148.0, 145.1, 141.3, 140.2, 139.3, 136.5,

136.4, 133.7, 131.6, 129.1, 128.7, 128.6, 128.2, 128.0, 127.9, 127.6,

127.2, 127.0, 126.8, 124.8, 124.7, 124.5, 123.7, 123.6, 122.4, 119.0,

114.2, 113.6, 111.41, 111.37, 109.5, 106.4, 105.6, 102.4, 100.9, 71.0,

70.7, 55.2, 54.9, 54.8, 45.1. HRMS (TOF) m/z: [M + H]⁺calcd for

C₅₁H₄₁O₆N₂S, 809.2680; found, 809.2659.

155.4, 148.1, 147.6, 147.2, 143.5, 134.1 (d, J_CF= 9 Hz), 133.0 (d, J_CF

= 4 Hz), 131.4, 131.3, 127.8, 124.1, 122.6, 117.5, 116.5 (d, J_CF= 21

Hz), 112.3, 111.8, 110.7, 108.5, 108.3, 105.4, 105.1, 102.5, 54.7, 54.5.

¹⁹F NMR (282 MHz, CDCl₃): δ −116.3. HRMS (TOF) m/z: [M +

H]⁺calcd for C₂₇H₂₀O₅N₂F, 471.1351; found, 471.1343.

3,11-Dihydroxy-14-(3-hydroxyphenyl)-2,12-dimethoxybenzo-

[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26d). Following general

procedure E, 25d (22.0 mg, 0.0256 mmol) gave the product, which

was puriﬁed by a reverse-phase HPLC column equilibrated with 100%

solvent A (50% methanol in water) and 0% B (isopropanol) at a ﬂow

rate of 9 mL/min. The eluting solvent system was programmed as

follows: a linear gradient from the starting solvent to 24% (v/v) B in

29 min; a linear gradient increasing from 24% to 60% (v/v) B for 35

min, holding for 10 min; increasing to 100% B in 20 min, holding for

N

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10 min; and re-equilibrating at initial conditions for 45 min. The

product 26d was obtained as a pale yellow sticky oil (9.8 mg, 0.0208

mmol, 81%). ¹H NMR (300 MHz, DMSO-d₆): δ 11.28 (s, 1H), 9.73

(s, 1H), 9.52 (s, 1H), 9.38 (d, J = 7.4 Hz, 1H), 7.50 (t, J = 8.2 Hz,

1H), 7.12−7.13 (m, 2H), 7.06−6.99 (m, 5H), 6.89 (s, 1H), 6.80 (s,

1H), 3.17 (s, 3H), 3.12 (s, 3H). ¹³C{¹H} NMR (75 MHz, DMSO-

d₆): δ 158.4, 155.4, 148.1, 147.4, 147.0, 143.4, 137.8, 131.3, 130.9,

130.6, 127.4, 123.9, 122.6, 122.0, 118.1, 117.5, 115.0, 112.2, 111.6,

110.5, 109.8, 108.3, 105.8, 105.4, 102.3, 54.7, 54.4. HRMS (TOF) m/

z: [M + H]⁺calcd for C₂₇H₂₁O₆N₂, 469.1394; found, 469.1389.

3,11-Dihydroxy-14-(4-hydroxyphenyl)-2,12-dimethoxybenzo-

[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26e). Following general

procedure E, compound 25e (25.0 mg, 0.029 mmol) gave the

product, which was puriﬁed by a reverse-phase HPLC column

equilibrated with 100% solvent A (50% methanol in water) and 0% B

(isopropanol) at a ﬂow rate of 9 mL/min. The eluting solvent system

was programmed as follows: a linear gradient from the starting solvent

to 27% (v/v) B in 32 min; a linear gradient increasing from 27% to

60% (v/v) B for 35 min, holding for 10 min; increasing to 100% B in

20 min, holding for 10 min; and re-equilibrating at initial conditions

for 45 min. The product 26e was obtained as a colorless foam (11.3

mg, 0.024 mmol, 83%). ¹H NMR (400 MHz, DMSO-d₆): δ 11.26 (s,

1H), 9.74 (s, 1H), 9.72 (s, 1H), 9.49 (s, 1H), 9.37 (d, J = 7.3 Hz,

1H), 7.40 (s, 1H), 7.38 (s, 1H), 7.12−7.07 (m, 4H), 7.01 (d, J = 7.4

Hz, 1H), 6.88 (s, 1H), 6.77 (s, 1H), 3.34 (s, 3H). ¹³C{¹H} NMR

(100 MHz, DMSO-d₆): δ 157.4, 155.4, 148.0, 147.3, 147.0, 143.3,

132.7, 131.3, 127.9, 126.4, 123.9, 122.6, 117.8, 116.3, 112.1, 111.6,

110.4, 109.8, 108.6, 105.8, 105.4, 102.3, 54.8, 54.5. HRMS (TOF) m/

z: [M + H]⁺calcd for C₂₇H₂₁O₆N₂, 469.1394; found, 469.1380.

3,11-Dihydroxy-2,12-dimethoxy-14-(4-(triﬂuoromethoxy)-

phenyl)benzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26f). Fol-

lowing general procedure E, compound 25f (20.0 mg, 0.0239

mmol) gave the product, which was puriﬁed by a reverse-phase

HPLC column equilibrated with 100% solvent A (50% methanol in

water) and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The

eluting solvent system was programmed as follows: a linear gradient

from the starting solvent to 60% (v/v) B in 65 min; a linear gradient

increasing from 60% to 80% (v/v) B for 30 min, holding for 10 min;

increasing to 100% B in 5 min, holding for 10 min; and re-

equilibrating at initial conditions for 45 min. The product 26f was

3,11-Dihydroxy-14-(3-hydroxy-4-methoxyphenyl)-2,12-

dimethoxybenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26h).

Following general procedure E, 25h (20.0 mg, 0.0225 mmol) gave

the product, which was puriﬁed by a reverse-phase HPLC column

equilibrated with 100% solvent A (50% methanol in water) and 0% B

(isopropanol) at a ﬂow rate of 9 mL/min. The eluting solvent system

was programmed as follows: a linear gradient from the starting solvent

to 32% (v/v) B in 35 min; a linear gradient increasing from 32% to

55% (v/v) B for 40 min, holding for 10 min; increasing to 100% B in

10 min, holding for 10 min; and re-equilibrating at initial conditions

for 45 min. The product 26h was obtained as a pale brown solid (9.1

mg, 0.0183 mmol, 81%). ¹H NMR (400 MHz, DMSO-d₆): δ 11.27 (s,

1H), 9.73 (s, 1H), 9.50 (s, 1H), 9.38−9.35 (m, 2H), 7.24 (d, J = 8.0

Hz, 1H), 7.13 (d, J = 7.2 Hz, 2H), 7.02−6.99 (m, 3H), 6.88 (s, 1H),

6.83 (s, 1H), 3.86 (s, 3H), 3.38 (s, 3H), 3.36 (s, 3H). ¹³C{¹H} NMR

(100 MHz, DMSO-d₆): δ 155.4, 148.0, 147.7, 147.4, 147.0, 143.4,

131.4, 131.2, 128.8, 127.7, 123.9, 122.6, 122.3, 118.5, 117.7, 113.8,

112.1, 111.6, 110.4, 109.7, 108.4, 105.9, 105.4, 102.3, 56.2, 54.8, 54.5.

The physical and spectroscopic data are in good agreement with those

previously reported.^7f

4-(3,11-Dihydroxy-2,12-dimethoxy-6-oxo-5,6-dihydrobenzo-

[7,8]indolizino[3,2-c]quinolin-14-yl)-N-methylbenzenesulfonamide

(26i). Following general procedure E, compound 25i (12.7 mg, 0.015

mmol) gave the product, which was puriﬁed by a reverse-phase HPLC

column equilibrated with 100% solvent A (50% methanol in water)

and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The eluting

solvent system was programmed as follows: a linear gradient from the

starting solvent to 20% (v/v) B in 25 min; a linear gradient increasing

from 20% to 55% (v/v) B for 50 min, holding for 10 min; increasing

to 100% B in 10 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26i was obtained as a pale yellow

foam (8.2 mg, 0.0011 mmol, 74%). ¹H NMR (400 MHz, DMSO-d₆):

δ 11.37 (s, 1H), 9.84 (s, 1H), 9.59 (s, 1H), 9.42 (d, J = 7.4 Hz, 1H),

8.10 (d, J = 8.2 Hz, 2H), 7.90 (d, J = 8.2 Hz, 2H), 7.69 (q, J = 5.0 Hz,

1H), 7.16 (s, 1H), 7.08 (d, J = 7.4 Hz, 1H), 6.90 (s, 1H), 6.80 (s,

1H), 6.49 (s, 1H), 3.38 (s, 3H), 3.28 (s, 3H), 3.25 (s, 3H). ¹³C{¹H}

NMR (100 MHz, DMSO-d₆): δ 155.3, 148.2, 147.6, 147.2, 143.5,

141.4, 139.2, 132.9, 131.4, 131.0, 130.4, 129.8, 127.7, 127.4, 124.1,

122.6, 117.2, 112.6, 111.8, 110.8, 108.1, 108.0, 105.2, 105.0, 102.5,

54.6, 54.3, 28.5. HRMS (TOF) m/z: [M + H]⁺calcd for

C₂₈H₂₄O₇N₃S, 546.1330; found, 546.1310.

1

obtained as a colorless foam (9.2 mg, 0.0172 mmol, 72%). H NMR

(600 MHz, DMSO-d₆): δ 11.29 (s, 1H), 9.82 (s, 1H), 9.55 (s, 1H),

9.39 (d, J = 7.3 Hz, 1H), 7.78 (d, J = 8.5 Hz, 2H), 7.71 (d, J = 7.9 Hz,

2H), 7.15 (s, 1H), 7.05 (d, J = 7.4 Hz, 1H), 6.90 (s, 1H), 6.85 (s,

1H), 6.54 (s, 1H), 3.30 (s, 3H), 3.27 (s, 3H). ¹³C{¹H} NMR (150

MHz, DMSO-d₆): δ 155.4, 148.3, 148.2, 147.6, 147.2, 143.5, 136.5,

134.0, 131.4, 131.2, 127.7, 124.1, 122.7, 122.5, 117.4, 112.5, 111.8,

110.8, 108.2, 108.1, 105.2, 105.0, 102.6, 54.4, 54.2. ¹⁹F NMR (282

MHz, CDCl₃): δ −59.6. HRMS (TOF) m/z: [M + H]⁺calcd for

C₂₈H₂₀O₆N₂F₃, 537.1268; found, 537.1248.

Methyl 4-(3,11-Dihydroxy-2,12-dimethoxy-6-oxo-5,6-

dihydrobenzo[7,8]indolizino[3,2-c]quinolin-14-yl)benzoate (26j).

Following general procedure E, compound 25j (25.0 mg, 0.0308

mmol) gave the product, which was puriﬁed by a reverse-phase HPLC

column equilibrated with 100% solvent A (50% methanol in water)

and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The eluting

solvent system was programmed as follows: a linear gradient from the

starting solvent to 33% (v/v) B in 38 min; a linear gradient increasing

from 33% to 65% (v/v) B for 40 min, holding for 10 min; increasing

to 100% B in 10 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26j was obtained as a pale brown

3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-

dimethoxybenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26g).

Following general procedure E, compound 25g (25.0 mg, 0.0281

mmol) gave the product, which was puriﬁed by a reverse-phase HPLC

column equilibrated with 100% solvent A (50% methanol in water)

and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The eluting

solvent system was programmed as follows: a linear gradient from the

starting solvent to 30% (v/v) B in 35 min; a linear gradient increasing

from 30% to 65% (v/v) B for 40 min, holding for 10 min; increasing

to 100% B in 10 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26g was obtained as a pale brown

1

sticky foam (10.5 mg, 0.0206 mmol, 67%). H NMR (600 MHz,

DMSO-d₆): δ 11.31 (s, 1H), 9.40 (d, J = 7.4 Hz, 1H), 8.27−8.26 (m,

2H), 7.79 (d, J = 7.9 Hz, 2H), 7.13 (s, 1H), 7.04 (d, J = 7.4 Hz, 1H),

6.90 (s, 1H), 6.81 (s, 1H), 6.52 (s, 1H), 3.93 (s, 3H), 3.24 (s, 3H),

3.22 (s, 3H). ¹³C{¹H} NMR (150 MHz, DMSO-d₆): δ 166.1, 155.4,

148.3, 147.3, 143.5, 142.3, 132.5, 131.5, 131.0, 130.1, 129.4, 127.4,

124.2, 122.6, 112.6, 111.8, 110.8, 108.5, 108.1, 105.6, 105.2, 102.5,

54.8, 54.5, 52.3. HRMS (TOF) m/z: [M + H]⁺calcd for

C₂₉H₂₃O₇N₂, 511.1500; found, 511.1507.

3,11-Dihydroxy-2,12-dimethoxy-14-(naphthalen-2-yl)benzo-

[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26l). Following general

procedure E, 25l (25.0 mg, 0.0311 mmol) gave the product, which

was puriﬁed by a reverse-phase HPLC column equilibrated with 100%

solvent A (50% methanol in water) and 0% B (isopropanol) at a ﬂow

rate of 9 mL/min. The eluting solvent system was programmed as

follows: a linear gradient from the starting solvent to 55% (v/v) B in

60 min; a linear gradient increasing from 55% to 80% (v/v) B for 30

min, holding for 10 min; increasing to 100% B in 10 min, holding for

1

solid (11.9 mg, 0.0238 mmol, 85%). H NMR (400 MHz, DMSO-

d₆): δ 11.27 (s, 1H), 9.71 (s, 1H), 9.51 (s, 1H), 9.37 (d, J = 7.6 Hz,

1H), 9.29 (s, 1H), 7.12−7.08 (m, 4H), 7.02−6.98 (m, 2H), 6.88 (s,

1H), 6.80 (s, 1H), 3.76 (s, 3H), 3.36 (s, 3H), 3.34 (s, 3H). ¹³C{¹H}

NMR (100 MHz, DMSO-d₆): δ 155.4, 148.6, 148.0, 147.4, 147.1,

146.5, 143.4, 131.4, 131.3, 127.9, 126.9, 124.0, 123.9, 122.6, 117.8,

116.4, 115.2, 112.0, 111.6, 110.4, 110.0, 108.6, 106.0, 105.5, 102.3,

56.0, 54.9, 54.5. The physical and spectroscopic data are in good

agreement with those previously reported.^7f

O

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10 min; and re-equilibrating at initial conditions for 45 min. The

product 26j was obtained as a pale yellow foam (11.2 mg, 0.0224

mmol, 72%). ¹H NMR (400 MHz, DMSO-d₆): δ 11.32 (s, 1H), 9.53

(s, 1H), 9.40 (d, J = 7.3 Hz, 1H), 8.25−8.22 (m, 2H), 8.05 (dd, J =

18.8, 7.6 Hz, 2H), 7.74 (d, J = 8.3 Hz, 1H), 7.61−7.58 (m, 2H), 7.04

(d, J = 7.5 Hz, 1H), 6.88 (s, 2H), 6.57 (s, 1H) 3.48 (s, 3H), 3.37 (s,

3H). ¹³C{¹H} NMR (100 MHz, DMSO-d₆): δ 155.5, 148.1, 147.6,

147.2, 143.5, 134.1, 133.6, 132.5, 131.6, 131.5, 131.4, 130.7, 129.7,

129.1, 127.9, 127.8, 127.8, 126.8, 126.7, 124.2, 122.8, 117.7, 112.5,

111.8, 110.8, 109.7, 108.5, 105.8, 105.4, 102.5, 54.5, 54.2. HRMS

(TOF) m/z: [M + H]⁺calcd for C₃₁H₂₃O₅N₂, 503.1602; found,

503.1598.

14-(Benzo[b]thiophen-2-yl)-3,11-dihydroxy-2, 12-

dimethoxybenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one (26m).

Following general procedure E, compound 25m (23.0 mg, 0.0284

mmol) gave the product, which was puriﬁed by a reverse-phase HPLC

column equilibrated with 100% solvent A (50% methanol in water)

and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The eluting

solvent system was programmed as follows: a linear gradient from the

starting solvent to 45% (v/v) B in 49 min; a linear gradient increasing

from 45% to 60% (v/v) B for 40 min, holding for 10 min; increasing

to 100% B in 10 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 26m was obtained as a colorless

sticky foam (4.8 mg, 0.0094 mmol, 33%). ¹H NMR (600 MHz,

DMSO-d₆): δ 11.37 (s, 1H), 9.41 (d, J = 7.4 Hz, 1H), 8.12 (d, J = 7.2

Hz, 1H), 8.00 (d, J = 7.2 Hz, 1H), 7.77 (s, 1H), 7.50−7.45 (m, 2H),

7.21 (s, 1H), 7.18 (s, 1H), 7.12 (d, J = 7.5 Hz, 1H), 6.90 (d, J = 11.0

Hz, 2H), 3.39 (s, 3H),3.39 (s, 3H). ¹³C{¹H} NMR (150 MHz,

DMSO-d₆): δ 155.2, 148.4, 148.0, 147.6, 143.7, 140.6, 140.1, 138.4,

132.6, 131.7, 128.7, 127.0, 124.9, 124.8, 124.5, 123.8, 122.5, 122.5,

117.0, 112.7, 111.6, 111.1, 107.8, 105.7, 105.2, 102.4, 99.9, 54.6, 54.1.

HRMS (TOF) m/z: [M + H]⁺calcd for C₂₉H₂₁O₅N₂S, 509.1166;

found, 509.1162.

1H), 7.03 (s, 1H), 6.92 (s, 1H), 6.89 (s, 1H), 6.80−6.77 (m, 4H),

5.39 (br s, 2H), 5.19 (s, 2H), 5.01 (s, 2H), 4.93 (t, J = 6.0 Hz, 2H),

3.85 (s, 3H), 3.85 (s, 3H), 3.84 (s, 3H), 3.76 (s, 3H), 3.02 (t, J = 6.0

Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃) δ 159.6, 158.6, 155.5,

148.4, 148.4, 147.5, 145.4, 138.8, 136.8, 136.6, 132.7, 130.6, 129.0,

128.6, 128.5, 127.9, 127.9, 127.7, 127.6, 127.5, 127.2, 127.2, 127.1,

127.1, 126.5, 120.9, 119.0, 115.6, 114.2, 114.2, 113.2, 112.5, 108.9,

105.5, 102.3, 94.5, 93.3, 84.4,71.1, 70.9, 56.0, 56.0, 55.3, 55.2, 45.2,

42.5, 28.7. HRMS (TOF) m/z: [M + H]⁺calcd for C₅₂H₄₅O₇N₂,

809.3221; found, 809.3209.

3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-dime-

thoxy-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(31). Following general procedure E, compound 24h (22.0 mg, 0.025

mmol) gave the product, which was puriﬁed by a reverse-phase HPLC

column equilibrated with 100% solvent A (50% methanol in water)

and 0% B (isopropanol) at a ﬂow rate of 9 mL/min. The eluting

solvent system was programmed as follows: a linear gradient from the

starting solvent to 30% (v/v) B in 45 min; a linear gradient increasing

from 30% to 65% (v/v) B for 35 min, holding for 10 min; increasing

to 100% B in 10 min, holding for 10 min; and re-equilibrating at initial

conditions for 45 min. The product 31 was obtained as a pale yellow

sticky foam (9.9 mg, 0.02 mmol, 80%). ¹H NMR (400 MHz, DMSO-

d₆): δ 11.06 (s, 1H), 9.28 (s, 2H), 9.18 (s,1H),7.01−6.99 (m, 2H),

6.88 (s, 1H), 6.86 (s, 1H), 6.72 (s, 1H), 6.68 (s, 1H), 6.65 (s, 1H),

4.77−4.74 (m, 2H), 3.74 (s, 3H), 3.31 (s, 3H), 3.27 (s, 3H), 2.98−

2.95 (m, 2H). ¹³C{¹H} NMR (100 MHz, DMSO-d₆): δ 155.3, 148.4,

146.2, 146.0, 145.9, 143.2, 132.8, 130.5, 126.9, 126.8, 126.3, 123.6,

119.0, 117.9, 116.2, 115.3, 114.9, 113.7, 109.2, 109.0, 105.3, 102.2,

56.0, 54.9, 54.7, 41.9, 28.0. HRMS (TOF) m/z: [M + H]⁺calcd for

C₂₈H₂₅O₇N₂, 501.1656; found, 501.1644.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-6-

oxo-5,6,8,9-tetrahydrobenzo[7,8]indolizino[3,2-c]quinoline-14-car-

baldehyde (32). To a stirred solution of oxalyl chloride (0.028 mL,

0.33 mmol) in CH₂Cl₂(1 mL) was added DMF (0.029 mL, 0.37

mmol) at 0 °C for 15 min. To this mixture at 0 °C was then added a

solution of the C1-H pyrrole lactam 17 (202 mg, 0.298 mmol) in

CH₂Cl₂(1 mL). The reaction was stirred for 3 h, at which time the

reaction was quenched with water (5 mL). The resulting mixture was

extracted with CH₂Cl₂(3 × 5 mL). The combined organic layers

were washed with water (5 mL) and brine (5 mL), dried over

anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced pressure

to give the crude product, which was further puriﬁed by column

chromatography on silica (50% EtOAc/hexane) to furnish the

corresponding C1-formyl pyrrole lactam 32 as a pale yellow solid

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

((trimethylsilyl)ethynyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]-

quinolin-6(5H)-one (28). Following general procedure F, compound

19 (50.0 mg, 0.062 mmol), trimethylsilylacetylene (0.014 mL, 0.098

mmol), Pd(PPh₃)₄(3.6 mg, 0.003 mmol), and CuI (1.2 mg, 0.006

mmol) were employed to furnish 28 as a yellow sticky oil (0.34 mg,

1

0.0044 mmol, 7%). H NMR (300 MHz, CDCl₃): δ 8.55 (s, 1H),

8.31 (s, 1H), 7.49−7.32 (m, 10H), 7.05 (s, 1H), 7.05 (s, 1H), 6.82−

6.78 (m, 4H), 5.38 (br s, 2H), 5.22 (s, 2H), 5.05 (s, 2H), 4.91 (t, J =

6.0 Hz, 2H), 4.00 (s, 3H), 4.00 (s, 3H), 3.77 (s, 3H), 3.00 (t, J = 6.0

Hz, 2H), 0.33 (s, 9H). HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₈H₄₇O₆N₂Si, 775.3198; found, 775.3205. Due to the small quantity

of 28, the ¹³C NMR spectrum of 28 could not be obtained, and its

¹³C NMR listing was not reported.

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

(phenylethynyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-

6(5H)-one (29). Following general procedure F, compound 19 (50.0

mg, 0.062 mmol), phenylacetylene (0.012 mL, 0.098 mmol),

Pd(PPh₃)₄(3.6 mg, 0.003 mmol), and CuI (1.2 mg, 0.006 mmol)

were employed to furnish compound 29 as a colorless sticky foam

(5.5 mg, 0.007 mmol, 11%). ¹H NMR (300 MHz, CDCl₃): δ 8.62 (s,

1H), 8.40 (s, 1H), 7.63−7.59 (m, 2H), 7.48−7.26 (m, 13H), 7.07 (s,

1H), 7.04 (s, 1H), 6.82−6.78 (m, 4H), 5.40 (br s, 2H), 5.22 (s, 2H),

5.05 (s, 2H), 4.95 (t, J = 6.0 Hz, 2H), 3.86 (s, 3H), 3.84 (s, 3H), 3.77

(s, 3H), 3.04 (t, J = 6.0 Hz, 2H). HRMS (TOF) m/z: [M + H]⁺calcd

for C₅₁H₄₃O₆N₂, 779.3116; found, 779.3098. Due to the small

quantity of 29 and some broad ¹³C NMR peaks, its ¹³C NMR

spectrum could not be obtained, and its ¹³C NMR listing was not

reported.

1

(100 mg, 0.0141 mmol, 48%). Mp: 220.5−221.3 °C; H NMR (300

MHz, CDCl₃): δ 10.43 (s, 1H), 9.35 (s, 1H), 7.49−7.24 (m, 11H),

7.06 (s, 1H), 7.03 (s, 1H), 6.92 (s, 1H), 6.82−6.78 (m, 3H), 5.40 (br

s, 2H), 5.25 (s, 2H), 5.07 (s, 2H), 4.96 (d, J = 6.0 Hz, 2H)., 4.11 (s,

3H), 3.97 (s, 3H), 3.77 (s, 3H), 3.00 (t, J = 6.0 Hz, 2H). ¹³C{¹H}

NMR (75 MHz, CDCl₃): δ 185.9, 158.7, 155.6, 149.9, 148.8, 148.4,

146.0, 145.3, 136.5, 136.4, 131.3, 129.3, 128.7, 128.6, 128.5, 128.2,

128.0, 127.9, 127.5, 127.2, 127.0, 121.0, 119.0, 115.0, 114.2, 113.4,

113.3, 112.0, 110.9, 101.8, 71.0, 56.5, 56.2, 55.2, 45.5, 42.2, 29.0.

HRMS (TOF) m/z: [M + H]⁺calcd for C₄₄H₃₉O₇N₂, 707.2752;

found, 707.2719.

3,11-Bis(benzyloxy)-14-chloro-2,12-dimethoxy-5-(4-methoxy-

benzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(33). Following general procedure B, C1-H pyrrole lactam 17 (50.0

mg, 0.074 mmol) and N-chlorosuccinimide (NCS; 15.0 mg, 0.11

mmol) were employed to furnish the C1-Cl pyrrole lactam 33 as a

1

white solid (41.5 mg, 0.058 mmol, 79%). Mp: 225.7−226.4 °C. H

NMR (300 MHz, CDCl₃): δ 8.35 (s, 1H), 8.07 (s, 1H), 7.49−7.31

(m, 10H), 7.06 (s, 1H), 7.03 (s, 1H), 6.82−6.78 (m, 4H), 5.38 (br s,

2H), 5.21 (s, 2H), 5.04 (s, 2H), 4.93 (t, J = 6.0 Hz, 2H), 3.99 (s, 3H),

3.99 (s, 3H), 3.77 (s, 3H), 2.99 (t, J = 6.0 Hz, 2H). ¹³C{¹H} NMR

(75 MHz, CDCl₃): δ 158.6, 155.4, 148.4, 148.2, 147.5, 145.3, 136.7,

136.6, 132.1, 130.7, 128.8, 128.63, 128.57, 128.0, 127.9, 127.5, 127.2,

127.12, 127.06, 123.1, 120.1, 118.2, 114.2, 113.5, 111.5, 109.3, 105.9,

102.6, 101.6, 71.1, 71.0, 56.23, 56.2, 55.2, 45.3, 42.4, 29.2. HRMS

(TOF) m/z: [M + H]⁺calcd for C₄₃H₃₈O₆N₂³⁵Cl, 713.2413; found,

3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxybenzyl)-14-

((4-methoxyphenyl)ethynyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-

c]quinolin-6(5H)-one (30). Following general procedure F, com-

pound 19 (50.0 mg, 0.062 mmol), 4-ethynylanisole (0.013 mL, 0.095

mmol), Pd(PPh₃)₄(3.6 mg, 0.003 mmol), and CuI (1.2 mg, 0.006

mmol) were employed to furnish compound 30 as a yellow foam (7.5

1

mg, 0.0092 mmol, 15%). H NMR (300 MHz, CDCl₃): δ 8.61 (s,

1H), 8.41 (s, 1H), 7.55−7.54 (m, 2H). 7.47−7.29 (m, 10H), 7.06 (s,

P

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713.2399. HRMS (TOF) m/z: [M + H]⁺calcd for C₄₃H₃₈O₆N₂³⁷Cl,

715.2401; found, 715.2375.

were washed with water (5 mL) and brine (5 mL), dried over

anhydrous Na₂SO₄, ﬁltered, and concentrated under reduced pressure

to give the crude product, which was further puriﬁed by column

chromatography on silica (50% EtOAc/hexane) to furnish compound

3,11-Bis(benzyloxy)-14-bromo-2,12-dimethoxy-5-(4-methoxy-

benzyl)-8,9-dihydrobenzo[7,8]indolizino[3,2-c]quinolin-6(5H)-one

(34). Following general procedure B, C1-H pyrrole lactam 17 (50.0

mg, 0.074 mmol) and N-bromosuccinimide (NBS; 20.0 mg, 0.11

mmol) were employed to furnish the C1-Br pyrrole lactam 34 as a

pale brown solid (48.0 mg, 0.063 mmol, 86%). Mp: 202.6−203.8 °C.

¹H NMR (300 MHz, CDCl₃): δ 8.62(s, 1H), 8.22 (s, 1H), 7.48−7.26

(m, 10H), 7.06 (s, 1H), 7.03 (s, 1H), 6.83−6.78 (m, 4H), 5.38 (br s,

2H), 5.22 (s, 2H), 5.05 (s, 2H), 4.97 (d, J = 6.0 Hz, 2H), 4.01 (s,

3H), 4.01 (s, 3H), 3.77 (s, 3H), 2.98 (t, J = 6.0 Hz, 2H). ¹³C{¹H}

NMR (75 MHz, CDCl₃): δ 158.6, 155.2, 148.2, 148.1, 147.4, 145.0,

136.7, 136.5, 133.3, 130.7, 128.7, 128.6, 128.5, 128.0, 127.9, 127.6,

127.5, 127.2, 127.1, 127.06, 124.1, 120.2, 119.1, 114.2, 113.4, 111.7,

109.6, 105.5, 102.5, 71.0, 70.9, 56.24, 56.16, 55.2, 45.3, 42.4, 29.2.

HRMS (TOF) m/z: [M + H]⁺calcd for C₄₃H₃₈O₆N₂⁷⁹Br, 757.1908;

found, 757.1920. HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₃H₃₈O₆N₂⁸¹Br, 759.1839; found, 759.1907.

1

38 as a yellow foam (27.4 mg, 0.037 mmol, 50%). H NMR (300

MHz, CDCl₃): δ 9.65 (d, J = 7.4 Hz, 1H), 7.83 (s, 1H), 7.73 (s, 1H),

7.49−7.31 (m, 10H), 7.06−7.04 (m, 3H), 6.91 (d, J = 7.5 Hz, 1H),

6.82−6.76 (m, 3H), 5.45 (br s, 2H), 5.21 (s, 2H), 5.00 (s, 2H), 4.12

(s, 3H), 4.03 (s, 3H), 3.97 (s, 3H), 3.75 (s, 3H). ¹³C{¹H} NMR (75

MHz, CDCl₃): δ 169.3, 158.6, 155.4, 149.6, 149.5, 148.5, 145.1,

136.4, 136.3, 134.3, 131.8, 128.8, 128.64, 128.56, 128.1, 127.9, 127.5,

127.4, 127.2, 127.0, 125.1, 123.4, 117.9, 114.2, 113.8, 112.3, 110.3,

109.3, 107.2, 106.0, 102.2, 100.5, 70.8, 70.6, 56.0, 55.9, 55.2, 52.4,

45.2. HRMS (TOF) m/z: [M + H]⁺calcd for C₄₅H₃₉O₈N₂, 735.2701;

found, 735.2693.

Assessment of Cytotoxicity by Viable Cell Count Using

Crystal Violet Assay. To evaluate the cytotoxicity of the newly

synthesized, lactam-containing lamellarin analogues, the compounds

were tested for the ability to suppress the viability of HeLa cancer

cells by using crystal violet staining. HeLa cells were cultured in

Dulbecco’s Eagle minimum enriched medium (DMEM) (HyClone

GE, USA), supplemented with 10% fetal bovine serum (HyClone GE,

USA), 100 IU/mL penicillin (Gibco, USA), and 100 μg/mL

streptomycin (Gibco, USA), in a humidiﬁed incubator at 37 °C

with 5% CO₂of atmospheric air. The cells were seeded into a 24-well

plate at cell density 1.5 × 10⁵cells per well and grown for 48 h before

challenging with the compounds for 18 h at concentrations of 0.312,

0.625, 1.25, 2.5, and 5 μM (for LamD, two additional concentrations

at 10 and 20 μM were included). The treated cells were removed

from the compound-containing media and stained with 0.5% crystal

violet in 20% methanol for 20 min. The stained cells were rinsed with

tap water and dried at room temperature. To quantify the cell

viability, the viable stained cells were eluted with 200 μL of 10% acetic

acid for 15 min before measuring at OD₅₉₀. The experiment was

performed at least 3 times with data obtained and analyzed for IC₅₀

and curve-ﬁtting R².

Immunoblotting Detection of Proteins Involved in Apop-

tosis in HeLa Cells Treated with Azalamellarins. HeLa cells were

cultured as described above. After 48 h incubation, the cells were

added with 2.5 μM of the lamellarins/azalamellarins for 8 h before

collecting for cell pellets. To prepare lysates, the cell pellets were

solubilized in NP-40 lysis buﬀer (1% (v/v) NP-40, 50 mM Tris-HCl

(pH 7.5), 150 mM NaCl, and 0.05% (w/v) SDS) supplemented with

complete protease inhibitor cocktail (Roche, Switzerland) with the

concentration suggested by the manufacturer. The total protein

concentrations were then determined by using a DC protein assay kit

(Biorad, USA) and then adjusted to a ﬁnal concentration at 1 μg/μL

in 1× SDS sample buﬀer (62.5 mM Tris-HCl, pH 6.8; 2% SDS; 10%

glycerol; 2 mM EDTA), before sonication at 27% amplitude for 7 s

twice. The prepared proteins were equally loaded at 15 μg per lane,

resolved in SDS-PAGE, and then blotted onto a nitrocellulose

membrane (Biorad, USA). Western detection was performed using

speciﬁc antibodies against the following proteins: cleaved caspase-3

(cCasp-3) (Cell Signaling Technology, CST no. 9664), cleaved

caspase-7 (cCasp-7) (CST no. 8438), cleaved PARP (CST no. 5625),

and β-tubulin (Invitrogen no. 32-2600). The western chemilumines-

cent signal was developed using the Clarity ECL substrate (Biorad,

USA) and recorded in the G:BOX system (Syngene, India). The

resulted band densities were analyzed by ImageJ (NIH, USA).

Methyl 3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxyben-

zyl)-6-oxo-5,6,8,9-tetrahydrobenzo[7,8]indolizino[3,2-c]quinoline-

14-carboxylate (32I). To a stirred solution of the C1-formyl pyrrole

lactam 32 (200 mg, 0.30 mmol) in 1,4-dioxane (7 mL) was added 2,3-

dimethyl-2-butadiene (0.64 mL, 5.92 mmol) at room temperature,

and the reaction was stirred for 15 min. A solution of NaClO₂(0.080

g, 0.89 mmol) and NaH₂PO₄(0.18 g, 1.48 mmol) in water (1 mL)

was then added. The mixture was stirred at room temperature for 18

h. At that time, the reaction was quenched with water (5 mL) and

extracted with EtOAc (3 × 5 mL). The combined organic layers were

washed with water (5 mL) and brine (5 mL), dried over anhydrous

Na₂SO₄, ﬁltered, and concentrated under reduced pressure to give the

crude carboxylic acid product, which was used in the next step

without further puriﬁcation.

To a stirred solution of the crude carboxylic acid in DMF (3 mL)

were added iodomethane (0.046 mL, 0.74 mmol) and cesium

carbonate (0.19 g, 0.59 mmol) at room temperature. The mixture was

stirred at room temperature for 5 h. At that time, the reaction was

quenched with water (3 mL) and extracted with EtOAc (3 × 5 mL).

The combined organic layers were washed with water (3 × 5 mL) and

brine (10 mL), dried over anhydrous Na₂SO₄, ﬁltered, and

concentrated under reduced pressure to give the crude product,

which was further puriﬁed by column chromatography on silica (40%

EtOAc/hexane) to furnish 32I as a yellow sticky foam (167 mg, 0.23

mmol, 77% (2 steps)). ¹H NMR (300 MHz, CDCl₃): δ 7.97 (s, 1H),

7.47−7.24 (m, 11H), 7.05 (s, 1H), 7.02 (s, 1H), 6.82−6.77 (m, 4H),

5.39 (br s, 2H), 5.20 (s, 2H), 5.03 (s, 2H), 4.91 (t, J = 6.0 Hz, 2H),

3.97 (s, 3H), 3.96 (s, 3H), 3.92 (s, 3H), 3.76 (s, 3H), 2.98 (t, J = 6.0

Hz, 2H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 168.5, 158.6, 155.4,

148.9, 148.2, 147.7, 145.2, 137.7, 136.6, 136.5, 130.9, 128.7, 128.6,

128.5, 127.98, 127.95, 127.9, 127.4, 127.2, 127.0, 126.0, 119.8, 119.6,

114.1, 113.0, 111.2, 110.6, 107.1, 104.7, 102.3, 71.0, 70.9, 56.1, 56.0,

55.2, 52.1, 45.2, 42.3, 28.9. HRMS (TOF) m/z: [M + H]⁺calcd for

C₄₅H₄₁O₈N₂, 737.2857; found, 737.2849.

ASSOCIATED CONTENT

* Supporting Information

The Supporting Information is available free of charge at

https://pubs.acs.org/doi/10.1021/acs.joc.1c01639.

■

sı

Methyl 3,11-Bis(benzyloxy)-2,12-dimethoxy-5-(4-methoxyben-

zyl)-6-oxo-5,6-dihydrobenzo[7,8]indolizino[3,2-c]quinoline-14-car-

boxylate (38). To a stirred solution of compound 32I (55.0 mg, 0.075

mmol) in 1,2-dichloroethane (2 mL) was added 2,3-dichloro-5,6-

dicyano-1,4-benzoquinone (DDQ; 26.0 mg, 0.12 mmol). The mixture

was heated to 60 °C by using an oil bath, at which the reaction was

stirred for 18 h. At that time, the reaction was quenched with water (3

mL). The resulting mixture was concentrated under reduced pressure

and extracted with EtOAc (3 × 5 mL). The combined organic layers

¹H and ¹³C{¹H} spectra for all products and ¹⁹F NMR

spectra for all ﬂuorine-containing compounds (PDF)

FAIR data, including the primary NMR FID ﬁles, for

compounds 11I, 12, 15, 16, 17, 18, 18I, 19, 20, 21, 23,

24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h, 24i, 24j, 24k,

Q

https://doi.org/10.1021/acs.joc.1c01639

J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

pubs.acs.org/joc

Article

Anti-Cancer Agents Med. Chem. 2008, 8, 746−760. and references

24l, 24m, 24n, 24o, 24p, 25a, 25b, 25c, 25d, 25e, 25f,

25g, 25h, 25i, 25j, 25k, 25l, 25m, 26a, 26b, 26c, 26d,

26e, 26f, 26g, 26h, 26i, 26j, 26l, 26m, 28, 29, 30, 31,

32, 32I, 33, 34, and 38 (ZIP)

́

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Almagthali, H.; Shaala, L. A.; Schmidt, E. W. Secondary Metabolites

of the Genus Didemnum: A Comprehensive Review of Chemical

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(h) Colligs, V. C.; Dialer, C.; Opatz, T. Synthesis of Lamellarin G

AUTHOR INFORMATION

Corresponding Author

■

Poonsakdi Ploypradith − Program in Chemical Sciences,

Chulabhorn Graduate Institute, Chulabhorn Royal Academy,

Bangkok 10210, Thailand; Laboratory of Medicinal

Chemistry, Chulabhorn Research Institute, Bangkok 10210,

Thailand; Center of Excellence on Environmental Health and

Toxicology, Commission on Higher Education, Ministry of

Education, Bangkok 10400, Thailand; orcid.org/0000-

0003-2893-1598; Email: poonsakdi@cri.or.th

Authors

Kanawut Klumthong − Program in Chemical Sciences,

Chulabhorn Graduate Institute, Chulabhorn Royal Academy,

Bangkok 10210, Thailand

Papornchanok Chalermsub − Applied Biological Sciences,

Environmental Health, Chulabhorn Graduate Institute,

Chulabhorn Royal Academy, Bangkok 10210, Thailand

Pattarawut Sopha − Applied Biological Sciences,

Environmental Health, Chulabhorn Graduate Institute,

Chulabhorn Royal Academy, Bangkok 10210, Thailand

Somsak Ruchirawat − Program in Chemical Sciences,

Chulabhorn Graduate Institute, Chulabhorn Royal Academy,

Bangkok 10210, Thailand; Laboratory of Medicinal

Chemistry, Chulabhorn Research Institute, Bangkok 10210,

Thailand; Center of Excellence on Environmental Health and

Toxicology, Commission on Higher Education, Ministry of

Education, Bangkok 10400, Thailand

Complete contact information is available at:

https://pubs.acs.org/10.1021/acs.joc.1c01639

Notes

̈

Trimethyl Ether by von Miller-Plochl-Type Cyclocondensation. Eur.

The authors declare no competing ﬁnancial interest.

J. Org. Chem. 2018, 2018, 4064−4070.

(5) For some recently developed synthetic routes, see: (a) Shirley,

H. J.; Koyioni, M.; Muncan, F.; Donohoe, T. J. Synthesis of

Lamellarin Alkaloids Using Orthoester-Masked α -Keto Acids. Chem.

Sci. 2019, 10, 4334−4338. (b) Kumar, V.; Awasthi, A.; Salam, A.;

Khan, T. Scalable Total Syntheses of Some Natural and Unnatural

Lamellarins: Application of a One-Pot Domino Process for

Regioselective Access to the Central 1,2,4-Trisubstituted Pyrrole

Core. J. Org. Chem. 2019, 84, 11596−11603. (c) Klintworth, R.; de

Koning, C. B.; Opatz, T.; Michael, J. P. A Xylochemically Inspired

Synthesis of Lamellarin G Trimethyl Ether via an Enaminone

Intermediate. J. Org. Chem. 2019, 84, 11025−11031; correction. J.

Org. Chem. 2019, 84, 15008. (d) Klintworth, R.; de Koning, C. B.;

Michael, J. P. Demethylative Lactonization Provides a Shortcut to

High-Yielding Syntheses of Lamellarins. J. Org. Chem. 2020, 85,

1054−1061. (e) Kumar, V.; Salam, A.; Kumar, D.; Khan, T. Concise

and Scalable Total Syntheses of Lamellarin Z and Other Natural

Lamellarins. ChemistrySelect 2020, 5, 14510−14514. (f) Morikawa,

D.; Morii, K.; Yasuda, Y.; Mori, A.; Okano, K. Convergent Total

Synthesis of Lamellarins and Their Congeners. J. Org. Chem. 2020, 85,

8603−8617. (g) Hwu, J. R.; Roy, A.; Panja, A.; Huang, W.-C.; Hu, Y.-

C.; Tan, K.-T.; Lin, C.-C.; Hwang, K.-C.; Hsu, M.-H.; Tsay, S.-C.

Domino Reaction for the Synthesis of Polysubstituted Pyrroles and

Lamellarin R. J. Org. Chem. 2020, 85, 9835−9843. (h) Silyanova, E.

A.; Samet, A. V.; Salamandra, L. K.; Khrustalev, V. N.; Semenov, V. V.

Formation of 3,4-Diarylpyrrole- and Pyrrolocoumarin Core of Natural

Marine Products via Barton-Zard Reaction and Selective O-

Demethylation. Eur. J. Org. Chem. 2020, 2020, 2093−2100.

ACKNOWLEDGMENTS

■

This research project is supported by the Thailand Science

Research and Innovation (TSRI; DBG6080007 for P.P.),

TSRI-Chulabhorn Research Institute (grant no. 313/2220),

and TSRI-Chulabhorn Graduate Institute, Chulabhorn Royal

Academy (FFB640035 Project Code 50171). Financial support

from The Scientist Development Scholarship in Honour of His

Majesty the King (for K.K.) is also acknowledged.

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S

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J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

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Article

condition, a low concentration of the corresponding hydroxide ion

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T

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An Expeditious Modular Hybrid Strategy for the Diversity-Oriented Synthesis of Lamellarins/Azalamellarins with Anticancer Cytotoxicity

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