Iron-Mediated Oxidative C–H Alkylation of S,S-Functionalized Internal Olefins via C(sp2)–H/C(sp3)–H Cross-Coupling

Title: Iron-Mediated Oxidative C-H Alkylation of S,S</

i>-Functionalized Internal Olefins via C(sp2)-H/

C(sp3)-H Cross-Coupling

Authors: Quannan Wang, Jiang Lou, Ping Wu, Kaikai Wu, and

Zhengkun Yu

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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201700654

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10.1002/adsc.201700654

Advanced Synthesis & Catalysis

FULL PAPER

DOI: 10.1002/adsc.201((will be filled in by the editorial staff))

Iron-Mediated Oxidative CH Alkylation of S,S-Functionalized

Internal Olefins via C(sp²)H/C(sp³)H Cross-Coupling

Quannan Wang,^a,bJiang Lou,^a,bPing Wu,^a,bKaikai Wu,^aand Zhengkun Yu*^,a,c

a

Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023,

Peoples Republic of China

b

University of Chinese Academy of Sciences, Beijing 100049, Peoples Republic of China

State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of

c

Sciences, 354 Fenglin Road, Shanghai 200032, Peoples Republic of China

Fax: +86-411-8437-9227; e-mail: zkyu@dicp.ac.cn

Received: ((will be filled in by the editorial staff))

Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please

delete if not appropriate))

Abstract. Catalytic amount of FeCl₃-mediated oxidative stituted pyrazoles and isoxazoles. The strategy to activate

CH alkylation of S,S-functionalized internal olefins, that is, an internal olefinic CH bond by polarizing its parent

α-oxo ketene dithioacetals and the analogs, was efficiently olefinic C=C bond with both the dialkylthio and an

achieved by means of simple ethers and toluene derivatives electron-withdrawing functionality was investigated. The

as the coupling partners, di-tert-butyl peroxide (DTBP) as mechanistic studies suggest a radical pathway for the

the oxidant, and DABCO·6H₂O as the additive. The C(sp²)H/C(sp³)H cross-coupling reactions. The present

alkylthio functionality is essential for the internal olefinic protocol provides a convenient route to tetrasubstituted

CH bond to undergo such alkylation with the O-adjacent olefins.

C(sp³)H bonds of ethers and benzylic CH bonds of

toluene derivatives, respectively. Tetrasubstituted olefins

were thus synthesized and further transformed to highly sub-

Keywords: iron; CH functionalization; internal olefins;

CH/CH cross-coupling; alkylation

CDC reactions of terminal olefins via directed

Introduction

C(sp³)H activation.^[10]Sanford, et al. realized

pyridine-directed,

palladium-catalyzed

aerobic

Multisubstituted olefin motifs are abundant in

numerous natural products, pharmaceuticals, and

functional materials.^[1]Continuous efforts have been

made to synthesize multisubstituted olefins, and

transition-metal-catalyzed cross-coupling has been

proven to be one of the most useful synthetic methods

in this area.^[2]Although vinyl halides,^[3]vinyl

pseudohalides such as vinyl boronic acids and

boronates,^[4]vinyl-metals such as vinylzirconium,^[4a]

vinylzinc,^[4c,5a]vinylmagnesium,^[5b]and vinylalumi-

num^[5c]compounds, and other reagents^[6]can be

utilized for this purpose, more concise and alternative

methods have been strongly desired. Recently, direct

CH functionalization has emerged as an important

method for the construction of a CC bond owing to

atom-economy, operational simplicity, and environ-

mental friendliness.^[7]In this regard, cross-

dehydrogenative-coupling (CDC)^[8]has been paid

particular attention, and transition-metal-catalyzed

oxidative C(sp³)H functionalization of ethers,

toluene derivatives, cycloalkanes, and common

alkanes have been documented.^[9]However, oxidative

C(sp²)H alkylation of olefins remains challenging

and only limited examples have recently been

reported. Yu, et al. reported palladium-catalyzed

C(sp³)H bond cleavage to establish an olefinic

C(sp²)C(sp³) bond.^[11]Wang and coworkers

documented copper/organo-catalyzed asymmetric

oxidative cross-coupling reactions between tertiary

amines and olefins using molecular oxygen as the

oxidant.^[12]Liu, et al. synthesized 1H-indenes through

DDQ-mediated cross-coupling between vinylic

C(sp²)H bonds and benzylic C(sp³)H bonds.^[13]

Wei lab achieved copper-catalyzed oxidative direct

alkylation of styrenes with unactivated alkanes.^[14]Lei,

et al. developed Cu(I)-catalyzed oxidative cross-

coupling between terminal olefinic CH bonds and

C(sp³)H bonds of simple ethers for the synthesis of

allylic ethers (Scheme 1a).^[15]Toluene derivatives

were also employed for similar transformations of

enone derivatives (Scheme 1b).^[16]Transition-metal-

catalyzed oxidative cross-coupling of comuarins and

flavones with unactivated C(sp³)H bonds were

recently reported.^[17]Unfortunately, transition-metal-

catalyzed oxidative alkylation of olefins has been

focused on terminal olefinic C(sp²)H bonds,

implicating that direct CH alkylation of internal

olefins still remains a challenge due to the steric

hindrance and electronic impact from the internal

olefin substrates.

1

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Advanced Synthesis & Catalysis

During the ongoing investigation of the reactivities

stabilization of the iron(III) salt mediator during the

reaction (Table 1, entry 4). Elevating the reaction

of internal olefins, we have recently developed a

strategy to activate internal olefinic CH bonds.^[18,19]

Introduction of an electron-withdrawing group such

as carbonyl, ester, or cyano, and one or two electron-

donating alkylthio functionalities to the two ends of

an olefinic C=C bond can intrinsically polarize the

carbon-carbon double bond and thus activate its

olefinic CH bond. In this regard, we successfully

furnished tetrasubstituted olefins through transition-

metal-catalyzed oxidative CH functionalization of

ketene dithioacetals^[20]as the polarized internal

olefinsubstartes,^[18b,18e,f]and an iron-catalyzed alkyla-

tion method was also established with styrenes as the

coupling partners (Scheme 1c).^[21]Due to the

advantages of iron catalysis in CH functionaliza-

tion,^[8e,9e,22]we reasonably envisioned that simple iron

salts might be applied as the catalysts or mediators in

the CDC reactions of such internal olefinic CH

bonds. Herein, we disclose FeCl₃-mediated oxidative

CH alkylation of ketene dithioacetals with simple

ethers and toluene derivatives for the synthesis of

tetrasubstituted olefins (Scheme 1d).^[23]

o

temperature to 130 or 140 C resulted in 3a in 85-

86% yields (Table 1, entries 5 and 6). The reaction

could not efficiently undergo in benzene, and did not

occur in both DMF and DMSO (Table 1, entries 79).

An air atmosphere deteriorated the reaction efficiency

to give 3a in 71% yield, and the best yield (92%) was

obtained in the case of using 3 equiv DTBP as the

oxidant (Table 1, entries 10 and 11). It was noted that

without either of FeCl₃and the oxidant the reaction

did not happen. Product 3a was not dectected in the

reaction mixture of 1a and 2a by GC analysis in the

absence of the FeCl₃catalyst, revealing that DTBP

itself could not promote the desired reaction without

the catalyst (Table 1, entries 12 and 13).

Table 1. Screening of reaction conditions.^[a]

FeCl₃

Additive

[mol%]

Temp

[^oC]

Yield^[b]

[%]

Entry

Solvent

[mol%]

1

2

10

5

1,4-dioxane

benzene

120

130

140

130

9

DBU

40

3

DBU

67

4

5

DABCO•6H₂O

69

5

86

6

5

85

7^c

5

59

8^[c]

9^[c]

10^[d]

11^[e]

12^[e]

13^[g]

5

DMF

0

5

DMSO

0

5

1,4-dioxane

71

5

92(80)^[f]

0

5

0

^[a]Conditions: 1a (0.3 mmol), additive (0.03 mmol), DTBP (0.6 mmol),

solvent (2 mL), in a 25-mL sealed tube, 0.1 MPa N₂, 24 h.

^[b]Determined by GC analysis with mesitylene as the internal standard.

^[c]Using 1,4-dioxane (3 mmol).

^[d]Under an air atmosphere.

^[e]Using 3 equiv DTBP.

Scheme 1. Oxidative CH alkylation of olefins.

Results and Discussion

Initially, the reaction of α-benzoyl ketene dithioacetal

1a and 1,4-dioxane (2a) was conducted to screen the

reaction conditions (Table 1). In the presence of 10

mol% FeCl₃and 2 equivalents of di-tert-butyl

peroxide (DTBP) as the oxidant, the reaction was

^[f]Isolated yield given in parentheses.

^[g]Without DTBP.

Under the optimal conditions the scope of ketene

dithioacetals 1 was investigated by means of their

reactions with 1,4-dioxane (2a) (Table 2). Cyclic α-

benzoyl ketene dithioacetal (1a) reacted with 2a to

afford the target product 3a in 80% isolated yield. In

a similar fashion, the reactions of methoxy and

chlorosubstituted aroyl ketene dithioacetals with 2a

gave products 3b3g (6487%). It is noted that

3MeO and 3Cl substituents exhibited a negative

impact on the reaction efficiency. The para-

substituents, i.e., 4F, 4Br, and 4CF₃on the aroyl

o

continued in 1,4-dioxane (2 mL) at 120 C for 24 h

under a nitrogen atmosphere, forming the target CH

alkylation product 3a in 9% yield (Table 1, entry 1).

Addition of 1,5-diaza-bicyclo[5.4.0]-5-undecene

(DBU) (10 mol%) obviously enhanced the yield to

40%, and use of 5 mol% FeCl₃remarkably improved

the yield to 67% (Table 1, entries 2 and 3). Moreover,

replacement of DBU by 1,4-diaza[2.2.2]bicyclo-

octane hydrate (DABCO·6H₂O) further increased the

product yield (69%), presumably due to its better

2

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Advanced Synthesis & Catalysis

moiety, demonstrated various electronic effects,

leading to products 3h3j in 7081% yields. Acetyl,

ester, and cyano-functionalized ketene dithioacetals

also efficiently underwent the reactions to generate

reactant and solvent for the reactions. The molecular

structure of tetrasubstituted olefin product 3a was

further confirmed by the X-ray single crystallogra-

phic structural analysis (Figure 1).^[24]

Table 2. Scope of ketene dithioacetals 1.^[a]

Figure 1. Molecular structure of compound 3a.

Next, the generality of the protocol was explored

by using various ethers 2 as the coupling partners

(Table 3). With cyclic α-oxo and α-cyano ketene

dithioacetals as the internal olefin substrates their

reactions with tetrahydrofuran (THF) afforded 4a

(83%), 4b (88%), and 4c (70%), respectively. As

compared to the corresponding reactions of the same

olefin substrates with 1,4-dioxane (2a) as shown in

Table 2, the formation of 4a and 4b was superior to

that of 3a (80%) and 3k (87%), while the generation

of 4c was inferior to that of 3m (87%). The reaction

of α-acetyl ketene di(methylthio)acetal with THF

efficiently formed 4e in 93% yield, whereas in other

cases THF reacted less efficiently than 2a to give 4d

(70%) and 4f (74%) over a longer period of 48 h. The

reactivity of tetrahydropyran (THP) was lower than

THF that its reactions with α-oxo ketene di(methyl-

thio)acetals only produced 4g (65%), 4h (72%), and

4i (74%) in moderate yields. 1,4-Benzodioxane also

exhibited a lower reactivity than aliphatic 1,4-dioxane

to react with α-acetyl ketene di(methylthio)acetal to

form 4j (60%). Acyclic ether, e.g., diethyl ether,

could undergo the oxidative cross-coupling reactions

via its methylene CH bond, affording 4k (52%) and

4l (62%), respectively. 1,4-Dimethoxybenzene

showed a moderate reactivity to form 4m (62%),

while anisole did not undergo the desired

reactionunder the stated conditions, which is

presumably attributed to the negative electronic effect

from the ether substrate. Two kinds of C(sp³)H

bonds are present in 1,3-dioxolane which participated

in the reaction to generate two separable isomers 4n

(37%) and 4n (24%), demonstrating that the O,O-

methylene CH bond is more reactive than the O-

methylene CH bond. Glycol dimethyl ether reacted

with the cyclic α-benzoyl ketene acetal, also

affording two regioisomers 4o (41%) and 4o (37%).

Similar results were obtained from the reactions of α-

acetyl and α-benzoyl ketene dithioacetals, yielding 4p

(45%) and 4p (25%), and 4q (35%) and 4q (27%),

respectively, revealing that the O-methylene CH

bond is more reactive than the methoxyl CH in

glycol dimethyl ether.

[a]

Conditions:

1 (0.5 mmol), 2a (3 mL), FeCl₃(0.025 mmol),

DABCO·6H₂O (0.05 mmol), DTBP (1.5 mmol), 130 ^oC, in a 25-mL

sealed tube, 0.1 MPa N₂, 24 h. Yields refer to the isolated products.

3k3m (8387%). Enlarging the dithioalkyl ring of 1

or using the open-chain ketene dithioacetal substrates

did not affect the formation of the target products 3n

(81%) and 3o (81%). In the cases of using the open-

chain methyl-substituted α-benzoyl ketene di(methyl-

thio)acetals products 3p3r (7285%) were obtained,

showing a steric effect from the 2methyl substituent.

The open-chain α-chlorobenzoyl ketene dithioacetals

exhibited a reactivitiy lower than that of their cyclic

analogs, forming 3s (74%) and 3t (60%), respectively.

However, 4Br-substituted di(methylthio)acetal exhi-

bited a reactivity similar to its cyclic analog to

produce 3u in 78% yield. Bulky α-(2naphthoyl) and

α-heteroaroyl (e.g., 2furoyl and 2thienoyl) ketene

dithioacetals reacted with 2a less efficiently, only

yielding 3v3x in 2141% yields. For the open-chain

acetyl, cyclopropylcarbonyl, ester or cyano-func-

tionalized ketene di(methylthio)acetals their oxidative

CH/CH cross-coupling reactions with 2a efficien-

tly underwent to afford 3y3z2 in 8187% yields. It

is noteworthy that 1,4-dioxane acted as both the

3

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Advanced Synthesis & Catalysis

Table 3. Scope of ethers2^[a]

and 2-chlorotoluenes also reacted with the internal

olefin, yielding 7n (79%) and 7o (79%), respectively.

However, 3Br, 4F, and 4acetyl-substituted

toluene derivatives exhibited a moderate reactivity,

and their reactions produced 7p7r in 5169% yields.

Both acyclic α-acetyl and cyclic α-benzoyl ketene

dithioacetals reacted well with toluene and its

derivatives to give 7s7v (6888%). Unexpectedly,

ethylbenzene could demonstrate a moderate reactivity

to form the relatively sterically hindered benzylation

products 7w and 7x (5559%). These results have

supplemented the previous work on CH benzylation

of electron-rich arenes^[26]and activated olefins^[22c]

through iron-catalyzed oxidative CH/CH cross-

coupling.

Scheme 2. Reactions of 1 in the absence of ethers.

In order to further probe into the CH bond

reactivity of the polarized internal olefins, the impact

of alkylthio(s) was investigated. Reacting α-acetyl

and α-benzoyl ketene (methylthio)acetals 8 with 1,4-

dioxane (2a) under the standard conditions gave the

oxidative C(sp²)H/C(sp³)H cross-coupling pro-

ducts 9a9c in 5775% yields [eq (1)]. As compared

to the corresponding di(methylthio)acetals, these

monothioacetal substrates exhibited a lower reactivity

[a]

Conditions:

1 (0.5 mmol), 2 (3 mL), FeCl₃(0.025 mmol),

DABCO·6H₂O (0.05 mmol), DTBP (1.5 mmol), 130 ^oC, in a 25-mL

sealed tube, 0.1 MPa N₂, 24-48 h. Yields refer to the isolated products.

^[b]24 h.

^[c]48 h.

^[d]1.5 mmol of ether in benzene (3 mL).

During the screening of conditions for the

reactions of 1 with 2, control experiments were

performed in the absence of 2 in benzene or toluene

solvent under the standard conditions (Scheme 2). In

benzene α-aroyl ketene dithioacetal substrates

underwent olefinic C(sp²)H methylation to form

5a5c (5662%) with DTBP as the methylating

agent,^[25]while in toluene benzylation occurred to

yield olefinic C(sp²)H benzylation product 7a (79%).

Thus, CH benzylation of α-oxo ketene dithioacetals

1 was investigated by replacement of the ether

substrates with toluene derivatives as the coupling

partners (Table 4). The reactions underwent effi-

ciently with toluene and its analogs to afford the CH

benzylated olefin products 7a7h (7379%). Both

electron-donating and withdrawing groups such as

MeO, Me, F, Cl, and CO₂Me were tolerant on the

aroyl moieties of the internal olefin substrates, and no

obvious steric effect was observed. Multimethyl-

substituted toluene derivatives such as o-, m-, and p-

xylenes, and mesitylene efficiently reacted with α-

benzoyl ketene di(methylthio)acetal to form the

benzylation products 7i7l (8087%). The reaction of

4-methoxy toluene gave two separable regioisomers

7m (59%) and 7m (17%), revealing that the benzylic

CH bond is more reactive than the methoxy CH

bond in the substituted toluene substrate. 4-tert-Butyl

to 2a. In the case of using 4,4-diphenyl-but-3-enone

(10) as the internal olefin substrate, the desired

reaction could not effectively occur under the stated

conditions, only forming the target product 11 in 10%

yield [eq (2)]. These results have unambiguously

demonstrated that the alkylthio functionality is

necessary for the CH functionalization of internal

olefins 1.^[18b,18e,f]

Then, the potential applications of the target

tetrasubstituted olefin products were explored

(Scheme 3). Treatment of 3o, 3y, 3z, and 7s with

excessive amount of hydrazine hydrate (10 equiv) in

refluxing toluene afforded multisubstituted pyrazole

derivatives 12a12d in excellent yields (8796%).

4

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Advanced Synthesis & Catalysis

Table 4. CH benzylation of α-oxo ketene dithioacetals 1.^[a]

Scheme4. Radical trapping experiments.

Additional control experiments were carried out to

probe into the reaction mechanism. Introduction of a

radical scavenger such as 2,2,6,6-tetramethyl-1-

piperidinyloxy (TEMPO) or 2,6-di-tert-butyl-4-

methylphenol (BHT) (3.5 equiv) to the reaction of α-

oxo ketene dithioacetal 1a and 1,4-dioxane (2a)

completely inhibited the oxidative CH/CH cross-

coupling reaction (Scheme 4), suggesting that a

radical pathway is involved in the catalytic cycle. The

alkyl-scavenger adduct 14 was detected in the

reaction mixture of 1a with 2a by HRMS determi-

nation, but it was not successfully isolated (see the

Supporting Information). The kinetic isotope effect

(KIE) experiments were also conducted under the

standard conditions by means of the reactions of 1a

and its deuterated form 1a[D] with 2a [eq (3)]. A

secondary isotope effect was observed with k_H/k_D=

1.1, which implicates that the internal olefinic

C(sp²)H bond cleavage is not involved in the rate-

determining step in the overall catalytic cycle (see the

Supporting Information for details).

[a]

Conditions:

1 (0.5 mmol), 6 (3 mL), FeCl₃(0.025 mmol),

DABCO·6H₂O (0.05 mmol), DTBP (1.5 mmol), 130 ^oC, in a 25-mL

sealed tube, 0.1 MPa N₂, 24 h. Yields refer to the isolated products.

A plausible mechanism is proposed in Scheme 5.

Initially, the homolytic cleavage of DTBP generates

two tert-butoxy radicals. Subsequent interaction of

ether 2a with tert-butoxy radical yields new radical

species A with release of tert-butyl alcohol by

hydrogen abstraction from the CH bond adjacent to

the ether oxygen atom. Addition of radical A to the

internal olefinic C=C bond of α-oxo ketene

dithioacetal 1a results in radical B which then reacts

with the high valent Fe(III) salt to form cationic

species C and the low valent Fe(II) species through a

single electron transfer (SET) process. Oxidation of

the Fe(II) species with DTBP regenerates the Fe(III)

mediator, and produces tert-butoxy anion as well

asthe tert-butoxy radical species. The alkylthio

functionalities may help to stabilize the cationic

species C due to their electron-donating property.

Abstraction of a proton from species C by basic tert-

butoxy anion generated from DTBP affords the target

product 3a.

Scheme 3. Synthetic applications of tetrasubstituted olefins.

The reactions of 3y, 3z, and 4e with hydroxylamine

(6 equiv) in refluxing ethanol gave fully substituted

isoxazoles 13a13c (5456%). These results have

depicted the potential applications of the resultant

tetrasubstituted olefins in the synthesis of

trisubstituted pyrazoles^[27]and fully functionlized

isoxazoles.

5

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Advanced Synthesis & Catalysis

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-phe-

nylethanone (3a): 123 mg, 80% yield; pale yellow solid,

m.p. 129-131 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS)

δ 7.69 (d, J = 7.1 Hz, 2 H, aromatic CH), 7.48 (t, 1 H,

aromatic CH), 7.40 (t, 2 H, aromatic CH), 4.71 (dd, J =

10.5 and 3.0 Hz, 1 H, OCHCH₂O), 4.12 and 3.89 (m each,

1:1 H, OCHCH₂O), 3.72 (m, 2 H, CH₂OCH₂CH₂O), 3.62

(m) and 3.53 (dd,

J = 11.7, 2.9 Hz) (1:1 H,

CHOCH₂CH₂O), 3.42, 3.31 and 3.16 (m, 1:2:1 H,

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

193.2 (Cq, C=O), 163.1 and 138.6 (Cq), 131.8, 128.5, and

128.4 (aromatic CH), 121.9 (Cq), 76.7 (OCHCH₂O), 67.2

(OCHCH₂O), 66.7 and 65.7 (OCH₂CH₂O), 37.4 and 37.2

(SCH₂CH₂S). HRMS (ESI) calcd for C₁₅H₁₆O₃S₂[M+H]⁺:

309.0619; found: 309.0617.

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-(2-

methoxyphenyl)et-hanone (3b): 133 mg, 80% yield; pale

yellow solid, m.p. 157-158 ^oC. ¹H NMR (400 MHz, CDCl₃,

25 ^oC, TMS) δ 7.34 (m, 1 H, aromatic CH), 7.18 (d, J = 7.4

Hz, 1 H, aromatic CH), 6.95 (t, 1 H, aromatic CH), 6.89 (d,

J = 8.3 Hz, 1 H, aromatic CH), 4.50 (dd, J = 10.6 and 3.0

Hz, 1 H, OCHCH₂O), 4.08 (t) and 3.85 (d, J = 10.7 Hz)

(1:1 H, OCHCH₂O), 3.78 (s, 3 H, OCH₃), 3.67 (m, 2 H,

CH₂OCH₂CH₂O), 3.57 (m) and 3.45 (dd, J = 11.6 and 3.0

Hz) (1:1 H, CH₂OCH₂CH₂O), 3.38 and 3.18 (m each, 2 H,

Scheme 5. Proposed mechanism.

Conclusion

In summary, iron-mediated oxidative CH alkylation

of S,S-functionalized internal olefins has been

efficiently realized by means of simple ethers and

toluene derivatives as the cross-coupling partners.

Tetrasubstituted olefins were thus synthesized and

efficiently applied for the preparation of trisubstituted

NH-pyrazoles and fully functionalized isoxazoles.

The present synthetic protocol provides a convenient

route to fully functionalized olefins.

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

190.8 (Cq, C=O), 168.4 (Cq), 156.1 (Cq), 131.0 (aromatic

CH), 129.9 (Cq), 128.2 (aromatic CH), 122.3 (Cq), 120.8

and 111.0 (aromatic CH), 76.2 (OCHCH₂O), 67.1

(OCHCH₂O), 66.3 and 65.5 (OCH₂CH₂O), 55.5 (OCH₃),

37.3 and 36.9 (SCH₂CH₂S). HRMS (ESI) calcd for

C₁₆H₁₈O₄S₂[M+H]⁺: 339.0725; found: 339.0729.

Experimental Section

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-(3-

methoxyphenyl)et-hanone (3c): 122 mg, 71% yield; pale

yellow solid, m.p. 136-137 ^oC. ¹H NMR (400 MHz, CDCl₃,

25 ^oC, TMS) δ 7.22 (m, 2 H, aromatic CH), 7.16 (d, J = 2.4

Hz, 1 H, aromatic CH), 6.95 (m, 1 H, aromatic CH), 4.65

(dd, J = 10.5 and 3.1 Hz, 1 H, OCHCH₂O), 4.06 (m) and

3.80 (dd, J = 13.5, 5.1 Hz) (1:1 H, OCHCH₂O), 3.73 (s, 3H,

OCH₃), 3.65 (m, 2 H, CH₂OCH₂CH₂O), 3.55 (m) and 3.45

(dd, J = 11.7 and 3.0 Hz) (1:1 H, CH₂OCH₂CH₂O), 3.36,

3.25 and 3.09 (m each, 1:2:1 H, SCH₂CH₂S). ¹³C NMR

(100 MHz, CDCl₃, 25 ^oC, TMS) δ 192.8 (Cq, C=O), 163.7,

159.5 and 139.9 (Cq), 129.4 (aromatic CH), 121.8 (Cq),

120.9 (s), 118.3 and 112.6 (aromatic CH), 76.5

(OCHCH₂O), 67.2 (OCHCH₂O), 66.6 and 65.7

(OCH₂CH₂O), 55.37 (OCH₃), 37.4 and 37.2 (SCH₂CH₂S).

HRMS (ESI) calcd for C₁₆H₁₈O₄S₂[M+H]⁺: 339.0725;

found: 339.0724.

General Considerations

¹H and ¹³C{¹H} NMR spectra were recorded on a 400

MHz spectrometer and all chemical shift values refer to

CDCl₃(δ(¹H), 7.26 ppm and δ(¹³C), 77.16 ppm). X-Ray

crystallographic analysis was achieved by the Analysis

Center, Dalian Institute of Chemical Physics, Chinese

Academy of Sciences. The HRMS analysis was obtained

by ESI on a GC-TOF mass spectrometer. Column

chromatographic purifications were performed on silica gel.

All the chemical reagents were purchased from

commercial sources and used as received unless otherwise

indicated.

Typical Procedure for the CH alkylation of ketene

dithioacetals 1 with ethers 2

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-(4-

methoxyphenyl)et-hanone (3d): 147 mg, 87% yield; pale

yellow solid, m.p. 103-105 ^oC. ¹H NMR (400 MHz, CDCl₃,

25 ^oC, TMS) δ 7.75 (d, J = 8.7 Hz, 2 H, aromatic CH), 6.88

(d, J = 8.7 Hz, 2 H, aromatic CH), 4.65 (dd, J = 10.3, 2.6

Hz, 1 H, OCHCH₂O), 4.02 (t) and 3.79 (m) (1:4 H, OCH₃

and OCHCH₂O), 3.71 and 3.59 (m each, 2:2 H,

OCH₂CH₂O), 3.38, 3.28 and 3.13 (m, 1:2:1 H, SCH₂CH₂S).

Under a nitrogen atmosphere, a mixture of α-oxo ketene

dithioacetal 1 (0.5 mmol), FeCl₃(4 mg, 0.025 mmol),

DABCO·6H₂O (11 mg, 0.05 mmol), and DTBP (219 mg,

1.5 mmol) in 1,4-dioxane (2a) (3 mL) was stirred in a 25-

mL sealed tube at 130 ^oC for 24 h. After cooled to ambient

temperature, the mixture was evaporated all the volatiles

under reduced pressure. The resultant residue was purified

by silica gel column chromatography (eluent: petroleum

o

¹³C (100 MHz, CDCl₃, 25 C, TMS) δ 192.6 (Cq, C=O),

163.0 (Cq of Ph), 156.9 (Cq), 131.4 (aromatic CH), 130.5

(Cq), 122.5 (Cq), 113.6 (aromatic CH), 77.2 (OCHCH₂O),

67.1 (OCHCH₂O), 67.0 and 65.7 (OCH₂CH₂O), 55.4

o

ether (60-90 C)/ethyl acetate = 4:1, v/v) to afford the

target product 3 or 4.

6

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

(OCH₃), 37.4 and 37.4 (SCH₂CH₂S). HRMS (ESI) calcd

for C₁₆H₁₈O₄S₂[M+H]⁺: 339.0725; found: 339.0719.

1-(2-Chlorophenyl)-2-(1,4-dioxan-2-yl)-2-(1,3-

(Cq), 134.6 (d, J = 3.1 Hz, Cq of Ph), 131.4 (d, J = 9.1 Hz,

aromatic CH), 121. 9 (Cq), 115.6 (d, J = 21.8 Hz, aromatic

CH), 76.9 (OCHCH₂O), 67.3 (OCHCH₂O), 66.8 and 65.8

(OCH₂CH₂O), 37.5 and 37.3 (SCH₂CH₂S). HRMS (ESI)

calcd for C₁₅H₁₅O₃S₂F [M+H]⁺: 327.0525; found:

327.0517.

dithiolan-2-ylidene)eth-anone (3e): 137 mg, 80% yield;

o

1

pale yellow solid, m.p. 130-131 C. H NMR (400 MHz,

o

CDCl₃, 25 C, TMS) δ 7.38 (dd, J = 7.9 and 1.2 Hz, 1 H,

aromatic CH), 7.30 (m, 2 H, aromatic CH), 7.21 (dd, J =

7.4 and 1.6 Hz, 1 H, aromatic CH), 4.45 (dd, J = 10.6 and

3.1 Hz, 1 H, OCHCH₂O), 4.04 (t) and 3.84 (d, J = 8.8 Hz)

(1:1 H, OCHCH₂O), 3.64 (m, 2 H, CH₂OCH₂CH₂O), 3.59

(m) and 3.50 (dd, J = 11.7 and 2.9 Hz) (1:1 H,

CH₂OCH₂CH₂O), 3.42 and 3.23 (m each, 2:2 H,

1-(4-Bromophenyl)-2-(1,4-dioxan-2-yl)-2-(1,3-

dithiolan-2-ylidene)eth-anone (3i): 146 mg, 76% yield;

o

1

pale yellow solid, m.p. 141-143 C. H NMR (400 MHz,

o

CDCl₃, 25 C, TMS) δ 7.56 (q, J = 8.5 Hz, 4 H, aromatic

CH), 4.64 (dd, J = 10.4 and 2.9 Hz, 1 H, OCHCH₂O), 4.10

(t) and 3.87 (d, J = 9.3 Hz) (1:1 H, OCHCH₂O), 3.71 (m, 2

H, CH₂OCH₂CH₂O), 3.61 (m) and 3.52 (dd, J = 11.7 and

2.8 Hz) (1:1 H, CH₂OCH₂CH₂O), 3.42, 3.32 and 3.17 (m

each, 1:2:1 H, SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃,

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS)

¹³C NMR (100 MHz, CDCl3, 25 oC, TMS) δ 189.4 (Cq,

C=O), 171.4, 139.7 and 130.6 (Cq), 130.4, 129.8, 127.8

and 126.9 (aromatic CH), 121.1 (Cq), 76.0 (OCHCH₂O),

67.2 (OCHCH₂O), 66.2 and 65.6 (OCH₂CH₂O), 37.6 and

37.1 (SCH₂CH₂S). HRMS (ESI) calcd for C₁₅H₁₅O₃S₂Cl

[M+H]⁺: 343.0229; found: 343.0232.

o

25 C, TMS) δ 192.2 (Cq, C=O), 163.5 and 137.4 (Cq),

131.8 and 130.3 (aromatic CH), 126.7 and 121.7 (Cq), 76.8

(OCHCH₂O), 67.4 (OCHCH₂O), 66.8 and 65.8

(OCH₂CH₂O), 37.6 and 37.4 (SCH₂CH₂S). HRMS (ESI)

calcd for C₁₅H₁₅O₃S₂Br [M+H]⁺: 386.9724; found:

386.9722.

1-(3-Chlorophenyl)-2-(1,4-dioxan-2-yl)-2-(1,3-

dithiolan-2-ylidene)eth-anone (3f): 109 mg, 64% yield;

o

1

pale yellow solid, m.p. 125-127 C. H NMR (400 MHz,

CDCl₃, 25 ^oC, TMS) δ 7.69 (s, 1 H, aromatic CH), 7.57 (d,

J = 7.6 Hz, 1 H, aromatic CH), 7.46 (d, J = 8.0 Hz, 1 H,

aromatic CH), 7.36 (t, 1 H, aromatic CH), 4.68 (dd, J =

10.5 and 2.9 Hz, 1 H, OCHCH₂O), 4.14 (t) and 3.91 (d, J =

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-(4-

(trifluoromethyl)p-henyl)ethanone (3j): 132 mg, 70%

o

1

yield; pale yellow solid, m.p. 133-135 C. H NMR (400

o

MHz, CDCl₃, 25 C, TMS) δ 7.78 (d, J = 8.0 Hz, 2 H,

aromatic CH), 7.69 (d, J = 8.1 Hz, 2 H, aromatic CH), 4.65

(dd, J = 10.5 and 2.9 Hz, 1 H, OCHCH₂O), 4.15 (t) and

3.91 (d, J = 9.6 Hz) (1:1 H, OCHCH₂O), 3.72 (m, 2 H,

CH₂OCH₂CH₂O), 3.63 and 3.52 (m each, 1:1 H,

CH₂OCH₂CH₂O), 3.47, 3.37 and 3.22 (m, 1:2:1 H,

9.4 Hz) (1:1 H, OCHCH₂O), 3.74 (m,

2

H,

CH₂OCH₂CH₂O), 3.63 (m) and 3.53 (dd, J = 11.7 and 2.7

Hz) (1:1 H, CH₂OCH₂CH₂O), 3.46, 3.36 and 3.20 (m each,

o

1:2:1 H, SCH₂CH₂S). ¹³C{¹H} (100 MHz, CDCl₃, 25 C,

o

TMS) δ 191.6 (Cq, C=O), 165.2, 140.5 and 134.6 (Cq),

131.7, 129.8, 128.6 and 126.6 (aromatic CH), 121.5 (Cq),

76.6 (OCHCH₂O), 67.4 (OCHCH₂O), 66.7 and 65.8

(OCH₂CH₂O), 37.5 and 37.4 (SCH₂CH₂S). HRMS (ESI)

calcd for C₁₅H₁₅O₃S₂Cl [M+H]⁺: 343.0229; found:

342.0230.

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

191.6 (Cq, C=O), 166.7 and 142.2 (Cq), 133.0 (q, J = 32.7

Hz, Cq of Ph), 128.7 (aromatic CH), 125.5 (q, J = 3.7 Hz,

aromatic CH), 123.8 (q, J = 272.6 Hz, CF₃), 121.3 (Cq),

76.5 (OCHCH₂O), 67.4 (OCHCH₂O), 66.6 and 65.8

(OCH₂CH₂O), 37.5 and 37.4 (SCH₂CH₂S). HRMS (ESI)

calcd for C₁₆H₁₅O₃S₂F₃[M+H]⁺: 377.0493; found:

377.0491.

1-(4-Chlorophenyl)-2-(1,4-dioxan-2-yl)-2-(1,3-

dithiolan-2-ylidene)eth-anone (3g): 140 mg, 82% yield;

o

1

pale yellow solid, m.p. 149-151 C. H NMR (400 MHz,

1-(1,4-Dioxan-2-yl)-1-(1,3-dithiolan-2-ylidene)pro-

pan-2-one (3k): 107 mg, 87% yield; white solid, m.p. 119-

o

CDCl₃, 25 C, TMS) δ 7.66 (d, J = 8.3 Hz, 2 H, aromatic

o

1

o

CH), 7.39 (d, J = 8.3 Hz, 2 H, aromatic CH), 4.65 (dd, J =

10.4 and 2.8 Hz, 1 H, OCHCH₂O), 4.11 (t) and 3.88 (d, J =

121 C. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.83

(dd, J = 10.7 and 3.1 Hz, 1 H, OCHCH₂O), 3.93 (m, 2 H,

OCHCH₂O), 3.84, 3.73 and 3.63 (m, 1:2:1 H, OCH₂CH₂O),

3.34 and 3.20 (m each, 2:2 H, SCH₂CH₂S), 2.36 (s, 3 H,

9.4 Hz) (1:1 H, OCHCH₂O), 3.73 (m,

2

H,

CH₂OCH₂CH₂O), 3.62 and 3.53 (m each, 1:1 H,

CH₂OCH₂CH₂O), 3.43, 3.33 and 3.18 (m each, 1:2:1 H,

COCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

193.2 (Cq, C=O), 166.3 and 121.5 (Cq), 77.0 (OCHCH₂O),

67.5 (OCHCH₂O), 66.8 and 65.8 (OCH₂CH₂O), 38.0 and

36.2 (SCH₂CH₂S), 28.9 (COCH₃). HRMS (ESI) calcd for

C₁₀H₁₄O₃S₂[M+H]⁺: 247.0463; found: 247.0454.

Ethyl 2-(1,4-dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-

acetate (3l): 114 mg, 83% yield; white solid, m.p. 91-93

^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.81 (dd, J

= 10.3 and 2.8 Hz, 1 H, OCHCH₂O), 4.16 (dd, J = 13.0

192.1 (Cq, C=O), 163.2, 138.2 and 136.9 (Cq), 130.2 and

128.8 (aromatic CH), 121.7 (Cq), 76.8 (OCHCH₂O), 67.3

(OCHCH₂O), 66.8 and 65.8 (OCH₂CH₂O), 37.5 and 37.3

(SCH₂CH₂S). HRMS (ESI) calcd for C₁₅H₁₅O₃S₂Cl

[M+H]⁺: 343.0229; found: 343.0232.

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)-1-(4-

fluorophenyl)etha-none (3h): 133 mg, 81% yield; pale

yellow solid, m.p. 135-137 ^oC. ¹H NMR (400 MHz, CDCl₃, and 5.9 Hz,

2

H, OCH₂CH₃), 3.73 (m,

6

H,

25 ^oC, TMS) δ 7.76 (dd, J = 8.6 and 5.5 Hz, 2 H, aromatic

CH), 7.09 (t, 2 H, aromatic CH), 4.66 (dd, J = 10.4 and 3.0

Hz, 1 H, OCHCH₂O), 4.10 (t) and 3.88 (d, J = 10.0 Hz)

(1:1 H, OCHCH₂O), 3.71 (m, 2 H, CH₂OCH₂CH₂O), 3.64

(m) and 3.55 (dd, J = 11.7 and 2.9 Hz) (1:1 H,

CH₂OCH₂CH₂O), 3.43, 3.33 and, 3.17 (m each, 1:2:1 H,

CH₂OCH₂CH₂O), 3.32 and 3.19 (m, 2:2 H, SCH₂CH₂S),

1.25 (t, 3 H, OCH₂CH₃). ¹³C NMR (100 MHz, CDCl₃, 25

^oC, TMS) δ 165.2 (Cq, C=O), 165.1 and 113.0 (Cq), 75.3

(OCHCH₂O), 67.2 (OCHCH₂O), 66.6 and 65.8

(OCH₂CH₂O), 60.6 (OCH₂CH₃), 37.5 and 37.1

(SCH₂CH₂S), 14.3 (OCH₂CH₃). HRMS (ESI) calcd for

C₁₁H₁₆O₄S₂[M+H]⁺: 277.0568; found: 277.0567.

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

192.0 (Cq, C=O), 165.1 (d, J = 253.3 Hz, Cq of Ph), 161.7

7

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

2-(1,4-Dioxan-2-yl)-2-(1,3-dithiolan-2-ylidene)aceto-

nitrile (3m): 100 mg, 87% yield; white solid, m.p. 122-

TMS) δ 194.9 (Cq, C=O), 143.6, 138.3, 137.5 and 136.9

(Cq), 134.1 (aromatic CH), 129.5 (aromatic CH), 128.3

(aromatic CH), 127.1 (aromatic CH), 76.6 (OCHCH₂O),

68.7 (OCHCH₂O), 66.8 and 66.1 (OCH₂CH₂O), 21.5 (Ph-

CH₃), 17.2 (SCH₃), 16.4 (SCH₃). HRMS (ESI) calcd for

C₁₆H₂₀O₃S₂[M+H]⁺: 325.0932; found: 325.0934.

o

1

o

124 C. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.30

(dd, J = 10.0 and 2.8 Hz, 1 H, OCHCH₂O), 3.80, 3.69 and

3.63 (m each, 3:2:1 H, CH₂OCH₂CH₂O), 3.56 (m, 4 H,

o

SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

166.8, 116.9 and 94.3 (Cq), 75.3 (OCHCH₂O), 68.5

(OCHCH₂O), 66.9 and 66.1 (OCH₂CH₂O), 39.6 and 38.3

(SCH₂CH₂S). HRMS (ESI) calcd for C₉H₁₁NO₂S₂

[M+Na]⁺: 252.0120; found: 252.0120.

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-(p-tolyl)-

prop-2-en-1-one (3r): 138 mg, 85% yield; white solid,

m.p. 112-114 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS)

δ 7.81 (d, J = 8.1 Hz, 2 H, aromatic CH), 7.24 (t, 2 H,

aromatic CH), 5.04 (dd, J = 10.2 and 2.8 Hz, 1 H,

OCHCH₂O), 3.81 (dd, J = 11.5 and 2.6 Hz), 3.65 (m) and

3.47 (m) (1:4:1 H, CH₂OCH₂CH₂O), 2.39 (s, 3 H, Ph-CH₃),

2.34 (s, 3 H, SCH₃), 2.08 (s, 3 H, SCH₃). ¹³C NMR (100

2-(1,4-Dioxan-2-yl)-2-(1,3-dithian-2-ylidene)-1-

phenylethanone (3n): 130 mg, 81% yield; pale yellow

solid, m.p. 128-130 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC,

TMS) δ 7.94 (d, J = 7.5 Hz, 2 H, aromatic CH), 7.53 (t, 1

H, aromatic CH), 7.43 (t, 2 H, aromatic CH), 4.85 (dd, J =

9.1 and 4.1 Hz, 1 H, OCHCH₂O), 3.77 and 3.69 (m each,

2:2 H, CH₂OCH₂CH₂O), 3.59 and 3.51 (m each, 1:1 H,

CH₂OCH₂CH₂O), 2.98 (m, 2 H, SCH₂), 2.74 (m, 2 H,

SCH₂), 2.09 (m, 2 H, SCH₂CH₂CH₂S). ¹³C NMR (100

MHz, CDCl₃, 25 ^oC, TMS)δ 195.0 (Cq, C=O), 138.6,

137.7 and 134.4 (C=CCH), 133.2, 129.5 and 128.6

(aromatic CH), 75.6 (OCHCH₂O), 68.2 (OCHCH₂O), 66.9

and 66.0 (OCH₂CH₂O), 29.1 and 28.8 (SCH₂), 23.92

(SCH₂CH₂CH₂S). HRMS (ESI) calcd for C₁₆H₁₈O₃S₂

[M+H]⁺: 323.0776; found: 323.0774.

o

MHz, CDCl₃, 25 C, TMS) δ 194.3 (Cq, C=O), 144.0,

143.5, 136.8 and 135.1 (Cq), 129.5 and 129.2 (aromatic

CH), 76.5 (OCHCH₂O), 68.6 (OCHCH₂O), 66.7 and 66.0

(OCH₂CH₂O), 21.8 (Ph-CH₃), 17.1 (SCH₃), 16.3 (SCH₃).

HRMS (ESI) calcd for C₁₆H₂₀O₃S₂[M+H]⁺: 325.0932;

found: 325.0935.

2-(1,4-Dioxan-2-yl)-1-(4-methoxyphenyl)-3,3-bis(me-

thylthio)prop-2-en-1-one (3s): 128 mg, 74% yield; white

solid, m.p. 108-110 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC,

TMS) δ 7.76 (d, J = 7.6 Hz, 1 H, aromatic CH), 7.42 (d, J

= 7.8 Hz, 1 H, aromatic CH), 7.36 (dd, J = 10.7 and 4.3 Hz,

1 H, aromatic CH), 7.28 (t, 1 H, aromatic CH), 5.02 (dd, J

= 9.1 and 3.9 Hz, 1 H, OCHCH₂O), 3.79 (m, 4 H,

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (3o): 125 mg, 81% yield; white solid,

m.p. 111-112 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) CH₂OCH₂CH₂O), 3.64 (dd, J = 11.6 and 2.1 Hz) and 3.55

δ 7.91 (d, J = 7.6 Hz, 2 H, aromatic CH), 7.53 (t, 1 H,

aromatic CH), 7.44 (t, 2 H, aromatic CH), 5.05 (dd, J =

10.2 and 2.5 Hz, 1 H, OCHCH₂O), 3.83, 3.68 and 3.48 (m

each, 1:4:1 H, CH₂OCH₂CH₂O), 2.35 (s, 3 H, SCH₃), 2.04

(s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS)δ

194.7 (Cq, C=O), 143.4, 137.6 and 137.2 (Cq), 133.1

(aromatic CH), 129.4 and 128.4 (aromatic CH), 76.6

(OCHCH₂O), 68.7 (OCHCH₂O), 66.8 and 66.1

(OCH₂CH₂O), 17.1 (SCH₃), 16.4 (SCH₃). HRMS (ESI)

calcd for C₁₅H₁₈O₃S₂[M+H]⁺: 311.0776; found: 311.0774.

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-o-tolyl-

prop-2-en-1-one (3p): 117 mg, 72% yield; white solid,

m.p. 93-94 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ

7.69 (d, J = 7.6 Hz, 1 H, aromatic CH), 7.33 (t, 1 H,

aromatic CH), 7.20 (t, 2 H, aromatic CH), 5.03 (dd, J =

10.0 and 2.9 Hz, 1 H, OCHCH₂O), 3.79 (m, 4 H,

CH₂OCH₂CH₂O), 3.63 and 3.53 (m each, 1:1 H,

CH₂OCH₂CH₂O), 2.60 (s, 3 H, SCH₃), 2.32 (s, 3 H, SCH₃),

1.89 (s, 3 H, Ph-CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC,

TMS)δ 196.6 (Cq, C=O), 145.5, 134.0, 137.9 and 137.8

(Cq) 131.6, 131.6, 131.2 and 125.1 (aromatic CH), 76.9

(OCHCH₂O), 68.8 (OCHCH₂O), 66.8 and 66.1

(OCH₂CH₂O), 21.5 (Ph-CH₃), 16.7 (SCH₃), 16.4 (SCH₃).

HRMS (ESI) calcd for C₁₆H₂₀O₃S₂[M+H]⁺: 325.0932;

found: 325.0930.

(m) (1:1 H, CH₂OCH₂CH₂O), 2.33 (s, 3 H, SCH₃), 1.91 (s,

o

3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

192.8 (Cq, C=O), 144.2, 140.4, 137.6 and 133.8 (Cq),

132.1, 131.4, 131.1and 126.1 (aromatic CH), 76.9

(OCHCH₂O), 68.6 (OCHCH₂O), 66.8 and 66.1

(OCH₂CH₂O), 16.7 (SCH₃), 16.4 (SCH₃). HRMS (ESI)

calcd for C₁₅H₁₇O₃S₂Cl [M+H]⁺: 345.0386; found:

345.0387.

1-(3-Chlorophenyl)-2-(1,4-dioxan-2-yl)-3,3-bis(me-

thylthio)prop-2-en-1-one (3t): 104 mg, 60% yield;

1

o

colorless liquid. H NMR (400 MHz, CDCl₃, 25 C, TMS)

δ 7.89 (s, 1 H, aromatic CH), 7.76 (d, J = 7.7 Hz, 1 H,

aromatic CH), 7.49 (m, 1 H, aromatic CH), 7.38 (t, 1 H,

aromatic CH), 5.04 (dd, J = 10.2 and 2.8 Hz, 1 H,

OCHCH₂O), 3.82 (dd, J = 11.5 and 2.7 Hz), 3.68 (m) and

3.49 (m) (1:4:1 H, CH₂OCH₂CH₂O), 2.35 (s, 3 H, SCH₃),

o

2.05 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ 193.5 (Cq, C=O), 142.8, 139.4, 138.0 and 134.8

(Cq), 139.8, 129.8, 129.1 and 127.6 (aromatic CH), 76.6

(OCHCH₂O), 68.6 (OCHCH₂O), 66.8 and 66.1

(OCH₂CH₂O), 17.1 (SCH₃), 16.4 (SCH₃). HRMS (ESI)

calcd for C₁₅H₁₇O₃S₂Cl [M+H]⁺: 345.0386; found:

345.0389.

1-(4-Bromophenyl)-2-(1,4-dioxan-2-yl)-3,3-bis(me-

thylthio)prop-2-en-1-one (3u): 152 mg, 78% yield; white

solid, m.p. 131-133 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC,

TMS) δ 7.76 (m, 2 H, aromatic CH), 7.57 (d, J = 7.0 Hz, 2

H, aromatic CH), 5.03 (d, J = 10.1 Hz, 1 H, OCHCH₂O),

3.81 (d, J = 11.5 Hz), 3.66 (m), and 3.47 (t, J = 11.5 Hz)

(1:4:1 H, CH₂OCH₂CH₂O), 2.34 (s, 3 H, SCH₃), 2.05 (s, 3

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-m-tolyl-

prop-2-en-1-one (3q): 118 mg, 73% yield; white solid,

m.p. 93-95 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ

7.76 (s, 1 H, aromatic CH), 7.68 (d, J = 6.9 Hz, 1 H,

aromatic CH), 7.33 (q, J = 7.5 Hz, 2 H, aromatic CH), 5.05

(dd, J = 10.2 and 2.6 Hz, 1 H, OCHCH₂O), 3.83 (dd, J =

11.5 and 2.4 Hz), 3.68 (m) and 3.49 (m) (1:4:1 H,

CH₂OCH₂CH₂O), 2.40 (s, 3 H, SCH₃), 2.36 (s, 3 H, SCH₃),

2.06 (s, 3 H, Ph-CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC,

o

H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

193.7 (Cq, C=O), 142.8, 137.6 and 136.5 (Cq), 131.7 and

130.8 (aromatic CH), 128.3 (Cq), 76.5 (OCHCH₂O), 68.5

(OCHCH₂O), 66.7 and 66.0 (OCH₂CH₂O), 17.1 (SCH₃),

8

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

16.3 (SCH₃). HRMS (ESI) calcd for C₁₅H₁₇O₃S₂Br [M+H]⁺: 2.30 (s, 3 H, SCH₃), 2.24 (s, 3 H, SCH₃), 2.09 (m, 1 H,

388.9881; found: 388.9883.

CH₂CHCH₂), 1.17 and 0.96 (m, 2 H, CHCH₂CH₂). ¹³C

NMR (100 MHz, CDCl₃, 25 C, TMS) δ 204.6 (Cq, C=O),

146.6 and 136.2 (Cq), 76.2 (OCHCH₂O), 68.6

o

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-(naphtha-

len-2-yl)prop-2-en-1-one (3v): 60 mg, 33% yield; pale

yellow solid, m.p. 128-130 ^oC. ¹H NMR (400 MHz, CDCl₃, (OCHCH₂O), 66.8 and 66.1 (OCH₂CH₂O), 23.2

o

25 C, TMS) δ 8.42 (s, 1 H, aromatic CH), 8.01 (m, 2 H,

aromatic CH), 7.88 (m, 2 H, aromatic CH), 7.56 (m, 2 H,

aromatic CH), 5.14 (dd, J = 10.2 and 2.8 Hz, 1 H,

OCHCH₂O), 3.90 (dd, J = 11.5 and 2.6 Hz), 3.70 (m) and

3.51 (m) (1:4:1 H, CH₂OCH₂CH₂O), 2.39 (s, 3 H, SCH₃),

(CH₂CHCH₂), 17.4 (SCH₃), 16.4 (SCH₃), 12.8 and 12.3

(CHCH₂CH₂). HRMS (ESI) calcd for C₁₂H₁₈O₃S₂[M+H]⁺:

275.0776; found: 275.0775.

Ethyl 2-(1,4-dioxan-2-yl)-3,3-bis(methylthio)acrylate

1

(3z1): 121 mg, 87% yield; colorless liquid. H NMR (400

2.05 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

MHz, CDCl₃, 25 C, TMS) δ 4.79 (t, 1 H, OCHCH₂O),

o

TMS) δ 194.8 (Cq, C=O), 143.6, 137.4, 135.8, 135.1 and

4.17 (m, 2 H, OCH₂CH₃), 3.64, 3.56 and 3.46 (m each,

2:3:1 H, CH₂OCH₂CH₂O), 2.23 (s, 3 H, SCH₃), 2.17 (s, 3

132.7 (Cq), 131.6, 129.9, 128.5, 128.4, 127.9, 126.7 and

124.7 (aromatic CH), 76.8 (OCHCH₂O), 68.8 (OCHCH₂O), H, SCH₃), 1.23 (t, 3 H, OCH₂CH₃). ¹³C NMR (100 MHz,

o

66.8 and 66.1 (OCH₂CH₂O), 17.2 (SCH₃), 16.4 (SCH₃).

HRMS (ESI) calcd for C₁₉H₂₀O₃S₂[M+H]⁺: 361.0932;

found: 361.0936.

CDCl₃, 25 C, TMS) δ 165.8 (Cq, C=O), 138.4 and 137.6

(Cq), 75.2 (OCHCH₂O), 68.1 (OCHCH₂O), 66.5 and 65.7

(OCH₂CH₂O), 61.0 (OCH₂CH₃), 17.2 (SCH₃), 16.0 (SCH₃),

14.0 (OCH₂CH₃). HRMS (ESI) calcd for C₁₃H₁₄O₂S₂

[M+H]⁺: 279.0725; found: 279.0725.

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)-1-(thiophen-

2-yl)prop-2-en-1-one (3w): 64 mg, 41% yield; pale

yellow solid, m.p. 105-107 ^oC. ¹H NMR (400 MHz, CDCl₃,

25 ^oC, TMS) δ 7.64 (d, J = 4.9 Hz, 1 H, aromatic CH), 7.58

(d, J = 3.7 Hz, 1 H, aromatic CH), 7.09 (m, 1 H, aromatic

CH), 5.01 (dd, J = 10.2 and 2.8 Hz, 1 H, OCHCH₂O), 3.65

(m, 6 H, CH₂OCH₂CH₂O), 2.35 (s, 3 H, SCH₃), 2.12 (s, 3

2-(1,4-Dioxan-2-yl)-3,3-bis(methylthio)acrylonitrile

1

(3z2): 101 mg, 87% yield; pale yellow liquid. H NMR

o

(400 MHz, CDCl₃, 25 C, TMS) δ 4.74 (dd, J = 10.2 and

2.8 Hz, 1 H, OCHCH₂O), 3.70 (m, 6 H, CH₂OCH₂CH₂O),

2.47 and 2.44 (s each, 3:3 H, SCH₃). ¹³C NMR (100 MHz,

o

H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

CDCl₃, 25 C, TMS) δ 161.0, 115.9 and 111.6 (Cq), 73.5

186.9 (Cq, C=O), 145.1, 143.0 and 138.7 (Cq), 134.3,

134.1 and 128.1 (aromatic CH), 76.2 (OCHCH₂O), 68.6

(OCHCH₂O), 66.8 and 66.0 (OCH₂CH₂O), 17.5 (SCH₃),

16.4 (SCH₃). HRMS (ESI) calcd for C₁₃H₁₆O₃S₃[M+H]⁺:

317.0340; found: 317.0339.

(OCHCH₂O), 68.4 (OCHCH₂O), 66.8 and 65.9

(OCH₂CH₂O), 18.3 (SCH₃), 17.7 (SCH₃). HRMS (ESI)

calcd for C₉H₁₃NO₂S₂[M+H]⁺: 232.0460; found: 232.0462.

2-(1,3-Dithiolan-2-ylidene)-1-phenyl-2-(tetrahydro-

furan-2-yl)ethanon-e (4a): 121 mg, 83% yield; pale

yellow solid, m.p. 106-108 ^oC. ¹H NMR (400 MHz, CDCl₃,

2-(1,4-Dioxan-2-yl)-1-(furan-2-yl)-3,3-bis(methyl-

thio)-prop-2-en-1-one (3x): 31 mg, 21% yield; pale

o

25 C, TMS) δ 7.68 (m, 2 H, aromatic CH), 7.41 (m, 3 H,

yellow solid, m.p. 116-118 ^oC. ¹H NMR (400 MHz, CDCl₃, aromatic CH), 4.83 (m, 1 H, OCHCH₂), 4.02 and 3.71 (m

25 ^oC, TMS) δ 7.60 (s, 1 H, aromatic CH), 7.10 (d, J = 3.5

Hz, 1 H, aromatic CH), 6.53 (dd, J = 3.1 and 1.1 Hz, 1 H,

aromatic CH), 5.01 (dd, J = 10.2 and 2.8 Hz, 1 H,

OCHCH₂O), 3.74 (m, 4 H, CH₂OCH₂CH₂O), 3.61 and

each, 1:1 H, OCH₂CH₂), 3.41, 3.28 and 3.13 (m each, 1:2:1

H, SCH₂CH₂S), 2.17 and 1.91 (m each, 1:3 H,

o

OCHCH₂CH₂). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS)

δ 193.6 (Cq, C=O), 160.6 and 139.0 (Cq), 131.3, 128.5 and

3.51 (m each, 1:1 H, CH₂OCH₂CH₂O), 2.35 (s, 3 H, SCH₃), 128.2 (aromatic CH), 124.9 (Cq), 79.6 (OCHCH₂) , 67.9

o

2.14 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

(OCH₂CH₂), 37.4 and 36.

9

(SCH₂CH₂S), 29.8

TMS) δ 182.3 (Cq, C=O), 153.3 (Cq), 147.1 (aromatic CH), (CHCH₂CH₂), 26.6 (CHCH₂CH₂). HRMS (ESI) calcd for

142.1 (Cq), 139.4 (Cq), 119.2 (aromatic CH), 112.5

(aromatic CH), 76.4 (OCHCH₂O), 68.7 (OCHCH₂O), 66.9

and 66.1 (OCH₂CH₂O), 17.8 (SCH₃), 16.4 (SCH₃). HRMS

(ESI) calcd for C₁₃H₁₆O₄S₂[M+H]⁺: 301.0568; found:

301.0569.

C₁₅H₁₆O₂S₂[M+H]⁺: 293.0670; found: 293.0671.

1-(1,3-Dithiolan-2-ylidene)-1-(tetrahydrofuran-2-

yl)propan-2-one (4b): 101 mg, 88% yield; pale yellow

liquid. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.94

(dd, J = 9.4 and 6.3 Hz, 1 H, OCHCH₂), 4.05 and 3.77 (m

each, 1:1 H, OCH₂CH₂), 3.28 and 3.10 (m each, 2:2 H,

1

o

3-(1,4-Dioxan-2-yl)-4,4-bis(methylthio)but-3-en-2-

one (3y): 108 mg, 87% yield; white solid, m.p. 101-102 ^oC. SCH₂CH₂S), 2.21 (s, 3 H, COCH₃), 1.99 (m, 4 H,

o

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.87 (dd, J =

CHCH₂CH₂). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

10.2, 3.0 Hz, H, OCHCH₂O), 3.60 (m, H,

1

6

193.3 (Cq, C=O), 162.9 and 124.3 (Cq), 79.6 (OCHCH₂),

67.6 (OCH₂CH₂), 37.5 and 36.2 (SCH₂CH₂S), 23.0

(CHCH₂CH₂), 28.5 (CHCH₂CH₂), 26.4 (COCH₃). HRMS

(ESI) calcd for C₁₀H₁₄O₂S₂[M+H]⁺: 231.0513; found:

231.0516.

CH₂OCH₂CH₂O), 2.34 (s, 3 H, SCH₃), 2.27 (s, 3 H, SCH₃),

2.21 (s, 3 H, CH₃CO). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC,

TMS) δ 202.8 (Cq, C=O), 146.7 and 134.0 (Cq), 76.3

(OCHCH₂O), 68.2 (OCHCH₂O), 66.6 and 66.0

(OCH₂CH₂O), 32.3 (CH₃CO), 17.3 (SCH₃), 16.3 (SCH₃).

HRMS (ESI) calcd for C₁₀H₁₆O₃S₂[M+H]⁺: 249.0619;

found: 249.0617.

2-(1,3-Dithiolan-2-ylidene)-2-(tetrahydrofuran-2-yl)-

1

acetonitrile (4c): 75 mg, 70% yield; colorless liquid. H

o

NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.58 (t, 1 H,

1-Cyclopropyl-2-(1,4-dioxan-2-yl)-3,3-bis(methyl-

thio)prop-2-en-1-one (3z): 111 mg, 81% yield; pale

yellow solid, m.p. 81-83 C. H NMR (400 MHz, CDCl₃,

25 ^oC, TMS) δ 4.89 (dd, J = 10.1 and 3.0 Hz, 1 H,

OCHCH₂O), 3.73 (dd, J = 8.1 and 2.0 Hz), 3.68 (dd, J =

11.5 and 2.9 Hz) and 3.56 (m) (2:1:3 H, CH₂OCH₂CH₂O),

OCHCH₂), 3.96 and 3.79 (dd each, 1:1 H, OCH₂CH₂), 3.51

(m, 4 H, SCH₂CH₂S), 2.04 (m, 4 H, CHCH₂CH₂). ¹³C

o

1

o

NMR (100 MHz, CDCl₃, 25 C, TMS) δ 163.4 (Cq, CN),

117.5 and 99.2 (Cq), 78.8 (OCHCH₂), 68.7 (OCH₂CH₂),

39.4 and 37.9 (SCH₂CH₂S), 31.2 and 26.0 (CHCH₂CH₂).

9

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

HRMS (ESI) calcd for C₉H₁₁NOS₂[M+H]⁺: 214.0360;

found: 214.0359.

(COCH₃), 30.2 (CHCH₂CH₂CH₂), 25.5 (CHCH₂CH₂CH₂),

23.4 (CHCH₂CH₂CH₂), 17.4 (SCH₃), 16.2 (SCH₃). HRMS

(ESI) calcd for C₁₁H₁₈O₂S₂[M+H]⁺: 247.0826; found:

247.0824.

3,3-Bis(methylthio)-1-phenyl-2-(tetrahydrofuran-2-

yl)prop-2-en-1-one (4d): 103 mg, 70% yield; colorless

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.93 (d,

J = 8.1 Hz, 2 H, aromatic CH), 7.48 (m, 3 H, aromatic CH),

5.23 (t, 1 H, OCHCH₂), 3.63 (dq, J = 22.1 and 7.6 Hz, 2 H,

OCH₂CH₂), 2.33 (s, 3 H, SCH₃), 2.24 and 2.07 (m each,

Ethyl 3,3-bis(methylthio)-2-(tetrahydro-2H-pyran-2-

1

yl)acrylate (4i): 102 mg,74% yield; colorless liquid. H

NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.58 (dd, J = 11.2

and 1.8 Hz, 1 H, OCHCH₂), 4.27 (m, 2 H, OCH₂CH₃), 3.96

(dd, J = 10.9 and 2.8 Hz) and 3.44 (m) (1:1 H, OCH₂CH₂),

2.29 (s, 3 H, SCH₃), 2.24 (s, 3 H, SCH₃), 1.78 and 1.51 (m

each, 2:4 H, CHCH₂CH₂CH₂CH₂), 1.31 (t, 3 H, OCH₂CH₃).

1:4 H, SCH₃and OCHCH₂CH₂), 1.83 (m,

2 H,

CH₂CH₂CH₂). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ

195.8 (Cq, C=O), 148.9, 137.6 and 133.4 (Cq), 133.0

(aromatic CH), 129.2 (aromatic CH), 128.5 (aromatic CH),

79.2 (OCHCH₂), 68.9 (OCH₂CH₂), 31.9 (CHCH₂CH₂),

o

¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 166.7 (Cq,

C=O), 143.2 and 135.2 (Cq), 77.6 (OCHCH₂), 68.7

26.2 (CHCH₂CH₂), 17.1 (SCH₃), 16.2 (SCH₃). HRMS (ESI) (OCH₂CH₂), 61.1 (OCH₂CH₃), 30.2 (CHCH₂CH₂CH₂),

calcd for C₁₄H₁₆O₂S₂[M+H]⁺: 295.0826; found: 295.0828.

4,4-Bis(methylthio)-3-(tetrahydrofuran-2-yl)but-3-

en-2-one (4e): 108 mg, 93% yield; white solid, m.p. 50-51

^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 5.00 (t, 1 H,

OCHCH₂), 3.71 (t, 2 H, OCH₂CH₂), 2.34 (s, 3 H, COCH₃),

2.25 (s, 3 H, SCH₃), 2.20 (s, 3 H, SCH₃), 2.15 and 1.85 (m

each, 1:3 H, CHCH₂CH₂). ¹³C NMR (100 MHz, CDCl₃, 25

^oC, TMS) δ 203.9 (Cq, C=O), 152.5 and 130.2 (Cq), 79.0

(OCHCH₂), 68.8 (OCH₂CH₂), 32.4 (CHCH₂CH₂), 31.8

(CHCH₂CH₂), 26.1 (COCH₃), 17.3 (SCH₃), 16.2 (SCH₃).

HRMS (ESI) calcd for C₁₀H₁₆O₂S₂[M+H]⁺: 233.0670;

found: 233.0668.

Ethyl 3,3-bis(methylthio)-2-(tetrahydrofuran-2-yl)-

acrylate (4f): 97 mg, 74% yield; colorless liquid. ¹H NMR

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 5.05 (t, J = 7.4 Hz, 1 H,

OCHCH₂), 4.24 (m, 2 H, OCH₂CH₃), 3.77 (m, 2 H,

OCH₂CH₂), 2.28 (s, 3 H, SCH₃), 2.25 (s, 3 H, SCH₃), 2.14

25.5 (CHCH₂CH₂CH₂), 23.5 (CHCH₂CH₂CH₂), 17.5

(SCH₃), 16.1 (SCH₃), 14.3 (OCH₂CH₃). HRMS (ESI) calcd

for C₁₂H₂₀O₃S₂[M+H]⁺: 277.0932; found: 277.0935.

3-(2,3-Dihydrobenzo[b][1,4]dioxin-2-yl)-4,4-bis(me-

thylthio)but-3-en-2-one (4j): 89 mg, 60% yield; yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 6.85 (m,

4 H, aromatic CH), 5.46 (dd, J = 9.0 and 2.6 Hz, 1 H,

OCHCH₂O), 4.25 (dd, J = 11.4 and 2.6 Hz) and 4.13 (dd, J

= 11.4 and 9.0 Hz) (1:1 H, OCHCH₂O), 2.49 (s, 3 H,

SCH₃), 2.36 (s, 3 H, SCH₃), 2.32 (s, 3 H, COCH₃). ¹³C

o

NMR (100 MHz, CDCl₃, 25 C, TMS) δ 202.2 (Cq, C=O),

144.1, 143.0, 142.9 and 137.5 (Cq), 121.9, 121.6, 117.4

and 117.3 (aromatic CH), 74.1 (OCHCH₂O), 65.8

(OCHCH₂O), 32.4 (COCH₃), 17.3 (SCH₃), 16.5 (SCH₃).

HRMS (ESI) calcd for C₁₄H₁₆O₃S₂[M+H]⁺: 297.0619;

found: 297.0622.

3-(1,3-Dithiolan-2-ylidene)-4-ethoxypentan-2-one

1

and 1.89 (m each, 1:3 H, OCHCH₂CH₂), 1.30 (t, J = 7.1 Hz, (4k): 60 mg, 52% yield; colorless liquid. H NMR (400

3 H, OCH₂CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS

δ 166.9 (Cq, C=O), 143.5 and 135.2 (Cq), 78.2 (OCHCH₂),

69.1 (OCH₂CH₂), 61.0 (OCH₂CH₃), 32.0 (CHCH₂CH₂)and

26.3 (CHCH₂CH₂), 17.5 (SCH₃), 16.2 (SCH₃), 14.2

(OCH₂CH₃). HRMS (ESI) calcd for C₁₁H₁₈O₃S₂[M+H]⁺:

263.0776; found: 263.0774.

MHz, CDCl₃, 25 C, TMS) δ 4.69 (q, J = 6.7 Hz, 1 H,

CH₃CHO), 3.41 and 3.2 (m each, 1:3 H, CH₃CH₂O and

SCH₂), 3.22 (m, 2 H, SCH₂), 2.32 (s, 3 H, COCH₃), 1.46 (d,

J = 6.7 Hz, 3 H, CH₃CHO), 1.18 (t, 3 H, CH₃CH₂O). ¹³C

NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ 194.2 (Cq, C=O),

162.6 and 126.3 (Cq), 76.5 (CH₃CHO), 64.1 (CH₃CH₂O),

37.9 and 36.1 (SCH₂CH₂S), 28.5 (COCH₃), 19.8

(CH₃CHO), 15.4 (CH₃CH₂O). HRMS (ESI) calcd for

C₁₀H₁₇O₂S₂[M+Na]⁺: 255.0489; found: 255.0487.

o

3,3-Bis(methylthio)-1-phenyl-2-(tetrahydro-2H-

pyran-2-yl)prop-2-en-1-one (4g): 100 mg, 65% yield;

1

o

colorless liquid. H NMR NMR (400 MHz, CDCl₃, 25 C,

TMS) δ 7.95 (d, J = 7.4 Hz, 2 H, aromatic CH), 7.53 (t, 1

H, aromatic CH), 7.44 (t, 2 H, aromatic CH), 4.71 (dd, J =

10.9 and 2.5 Hz, 1 H, OCHCH₂), 3.90 and 3.46 (m each,

1:1 H, OCH₂CH₂), 2.34 (s, 3 H, SCH₃), 2.04 (s, 3 H,

3-(Bis(methylthio)methylene)-4-ethoxypentan-2-one

1

(4l): 73 mg, 62% yield; colorless liquid. H NMR (400

o

MHz, CDCl₃, 25 C, TMS) δ 4.75 (q, J = 6.6 Hz, 1 H,

CH₃CHO), 3.47 (m, 2 H, CH₃CH₂O), 2.33 (s, 3 H,

COCH₃), 2.28 (s, 3 H, SCH₃), 2.24 (s, 3 H, SCH₃), 1.31 (d,

J = 6.6 Hz, 3 H, CH₃CHO), 1.14 (t, 3 H, CH₃CH₂O).

SCH₃),

1.72

and

1.49

(m each,

3:3

H,

o

CHCH₂CH₂CH₂CH₂). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ 195.3 (Cq, C=O), 148.4, 137.7 and 134.3 (Cq),

133.0, 129.6 and 128.4 (aromatic CH), 78.6 (OCHCH₂),

o

¹³CNMR (100 MHz, CDCl₃, 25 C, TMS) δ 203.1 (Cq,

C=O), 152.4 and 132.6 (Cq), 75.2 (CH₃CHO), 64.6

(CH₃CH₂O), 32.0 (COCH₃), 20.4 (CH₃CHO), 17.4 (SCH₃),

16.3 (SCH₃), 15.3 (CH₃CH₂O). HRMS (ESI) calcd for

C₁₀H₁₈O₂S₂[M+Na]⁺: 257.0646; found: 257.0640.

68.7

(OCH₂CH₂),

30.4

(CHCH₂CH₂CH₂),

25.5

(CHCH₂CH₂CH₂), 23.7 (CHCH₂CH₂CH₂), 17.2 (SCH₃),

16.2 (SCH₃). HRMS (ESI) calcd for C₁₆H₂₀O₂S₂[M+H]⁺:

309.0983; found: 309.0980.

2-((4-Methoxyphenoxy)methyl)-3,3-bis(methylthio)-

1-phenylprop-2-en-1-one (4m): 112 mg, 62% yield;

4,4-Bis(methylthio)-3-(tetrahydro-2H-pyran-2-yl)but

-3-en-2-one (4h): 89 mg, 72% yield; white solid, m.p. 65-

o

colorless liquid. ¹H NMR (400 MHz, CDCl₃, 25 C, TMS)

67 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.57 (dd, δ 7.91 (d, J = 7.2 Hz, 2 H, aromatic CH), 7.54 (t, 1 H,

J = 8.8 and 4.7 Hz, 1 H, OCHCH₂), 3.92 (dd, J = 11.1 and

3.6 Hz) and 3.40 (m) (1:1 H, OCH₂CH₂), 2.34 (s, 3 H,

COCH₃), 2.26 (s, 3 H, SCH₃), 2.21 (s, 3 H, SCH₃), 1.90

and 1.52 (m, 1:5 H, CHCH₂CH₂CH₂CH₂). ¹³C NMR (100

MHz, CDCl₃, 25 C, TMS)δ 203.3 (Cq, C=O), 152.0 and

130.6 (Cq), 78.4 (OCHCH₂), 68.6 (OCH₂CH₂), 32.4

aromatic CH), 7.44 (t, 2 H, aromatic CH), 6.78 (m, 4 H,

aromatic CH), 4.99 (s, 2 H, OCH₂), 3.74 (s, 3 H, OCH₃),

2.39 and 2.11 (s each, 3:3 H, SCH₃). ¹³C NMR (100 MHz,

CDCl₃, 25 C, TMS) δ 196.3 (Cq, C=O), 154.2, 152.5,

142.9 and 141.3 (Cq), 137.7 (C=CCH), 133.1, 129.3, 128.5,

116.2 and 114.6 (aromatic CH), 68.9 (OCH₂), 55.8 (OCH₃),

o

10

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

17.2 and 16.7 (SCH₃). HRMS (ESI) calcd for C₁₉H₂₀O₃S₂

[M+Na]⁺: 383.0752; found: 383.0747.

(OCH₃), 37.9 and 36.2 (SCH₂CH₂S), 28.5 (COCH₃).

HRMS (ESI) calcd for C₁₀H₁₆O₃S₂[M+Na]⁺: 271.0439;

found: 271.0438.

2-(1,3-Dioxolan-2-yl)-3,3-bis(methylthio)-1-(p-tolyl)-

prop-2-en-1-one (4n): 57 mg, 37% yield; colorless liquid.

3-(1,3-Dithiolan-2-ylidene)-4-(2-methoxyethoxy)-

o

1

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.86 (d, J =

butan-2-one (4p): 25 mg, 52% yield; colorless liquid. H

o

8.1 Hz, 2 H, aromatic CH), 7.25 (d, J = 7.8 Hz, 2 H,

aromatic CH), 6.13 (s, 1 H, OCHO), 3.81 (m, 4 H,

OCH₂CH₂O), 2.40 (s, 3 H, SCH₃), 2.37 (s, 3 H, SCH₃),

2.14 (s, 3 H, Ph-CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC,

TMS) δ 193.8 (Cq, C=O), 144.2, 143.3, 140.7 and 134.7

(Cq), 129.7 (aromatic CH), 129.3 (aromatic CH), 101.4

(OCHO), 65.5 (OCH₂CH₂O), 21.9 (Ph-CH₃), 17.1 (SCH₃),

16.5 (SCH₃). HRMS (ESI) calcd for C₁₅H₁₈O₃S₂[M+H]⁺:

311.0776; found: 311.0775.

NMR (400 MHz, CDCl₃, 25 C, TMS) δ 4.52 (s, 2 H,

CH₂OCH₂CH₂), 3.63 and 3.56 (m each, 2:2 H, SCH₂CH₂S),

3.38 (m, 5 H, OCH₃and CH₂OCH₂CH₂), 3.32 (m, 2 H,

CH₂OCH₂CH₂), 2.34 (s, 3 H, COCH₃). ¹³C NMR (100

o

MHz, CDCl₃, 25 C, TMS) δ 194.5 (Cq, C=O), 167.4 and

121.4 (Cq), 72.0 (CH₂OCH₂CH₂), 71.4 (CH₂OCH₂CH₂),

69.0 (CH₂OCH₂CH₂), 59.1 (OCH₃), 39.3 and 35.8

(SCH₂CH₂S), 27.2 (COCH₃). HRMS (ESI) calcd for

C₁₀H₁₆O₃S₂[M+Na]⁺: 271.0439; found: 271.0434.

2-(1,3-Dioxolan-4-yl)-3,3-bis(methylthio)-1-(p-tolyl)-

prop-2-en-1-one (4n): 38 mg, 24% yield; colourless

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.84 (d,

J = 8.2 Hz, 2 H, aromatic CH), 7.27 (d, J = 7.9 Hz, 2 H,

aromatic CH), 5.37 (t, 1 H, OCHCH₂O), 4.84 and 4.73 (s

each, 1:1 H, OCH₂O), 4.21 (dd, J = 8.3 and 6.9 Hz) and

3.97 (dd, J = 8.3 and 7.1 Hz) (1:1 H, OCHCH₂O), 2.41 (s,

3 H, Ph-CH₃), 2.37 (s, 3 H, SCH₃), 2.12 (s, 3 H, SCH₃).

2-(Bis(methylthio)methylene)-3,4-dimethoxy-1-phe-

nylbutan-1-one (4q): 54 mg, 35% yield; colorless liquid.

o

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.85 (d, J =

7.3 Hz, 2 H, aromatic CH), 7.47 (t, 1 H, aromatic CH),

7.38 (t, 2 H, aromatic CH), 4.83 (dd, J = 7.0 and 4.7 Hz, 1

H, CHOCH₃), 3.48 (dd, J = 10.2 and 7.1 Hz) and 3.40 (m)

(1:4 H, CH₃OCHCH₂and OCH₃), 3.22 (s, 3 H, OCH₃),

2.30 (s, 3 H, SCH₃), 2.04 (s, 3 H, SCH₃). ¹³C NMR (100

o

¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 194.7 (Cq,

MHz, CDCl₃, 25 C, TMS) δ 194.7 (Cq, C=O), 144.4,

C=O), 144.9, 144.4, 136.1 and 134.9 (Cq), 129.5 and 129.4

(aromatic CH), 95.9 (OCH₂O), 75.6 (OCHCH₂O), 69.2

(OCHCH₂O), 21.9 (Ph-CH₃), 17.2 (SCH₃), 16.4 (SCH₃).

HRMS (ESI) calcd for C₁₅H₁₈O₃S₂[M+H]⁺: 311.0776;

found: 311.0779.

138.5 and 137.3 (Cq), 133.0, 129.1 and 128.4 (aromatic

CH), 80.8 (CHOCH₃), 74.0 (CHCH₂OCH₃), 59.0 (OCH₃),

58.1 (OCH₃), 17.1 (SCH₃), 16.5 (SCH₃). HRMS (ESI)

calcd for C₁₅H₂₀O₃S₂[M+Na]⁺: 335.0752; found: 335.0755.

2-((2-Methoxyethoxy)methyl)-3,3-bis(methylthio)-1-

phenylprop-2-en-1-one (4q): 42 mg, 27% yield; pale

2-(1,3-Dithiolan-2-ylidene)-3,4-dimethoxy-1-phenyl-

butan-1-one (4o): 64 mg, 41% yield; pale yellow liquid.

o

yellow liquid. ¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ

o

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.59 (m, 2 H,

7.91 (d, J = 7.6 Hz, 2 H, aromatic CH), 7.53 (t, 1 H,

aromatic CH), 7.44 (t, 2 H, aromatic CH), 4.56 (s, 2 H,

CH₂OCH₂CH₂), 3.59 and 3.43 (m each, 2:2 H,

OCH₂CH₂O), 3.26 (s, 3 H, OCH₃), 2.36 (s, 3 H, SCH₃),

aromatic CH), 7.44 (m, 3 H, aromatic CH), 4.59 (dd, J =

8.2 and 4.3 Hz, 1 H, CHOCH₃), 3.79 (dd, J = 10.4 and 8.2

Hz) and 3.45 (m) (1:1 H, CHCH₂OCH₃), 3.40 and 3.34 (m

each, 4:1 H, OCH₃and SCH₂), 3.27 and 3.16 (m each, 4:1

o

2.08 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

o

H, OCH₃and SCH₂). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ 196.5 (Cq, C=O), 143.4, 140.7 and 137.5 (Cq),

TMS) δ 194.0 (Cq, C=O), 161.7 and 139.5 (Cq), 131.2,

128.5 and 128.1 (aromatic CH), 122.3 (Cq), 81.0

(CHOCH₃), 72.9 (CHCH₂OCH₃), 59.0 (OCH₃), 57.0

(OCH₃), 37.5 and 37.4 (SCH₂CH₂S). HRMS (ESI) calcd

for C₁₅H₁₈O₃S₂[M+Na]⁺: 333.0595; found: 333.0594.

2-(1,3-Dithiolan-2-ylidene)-3-(2-methoxyethoxy)-1-

phenylpropan-1-one (4o): 58 mg, 37% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.76 (m,

2 H, aromatic CH), 7.42 (m, 3 H, aromatic CH), 4.34 (s, 2

H, CH₂OCH₂CH₂), 3.59 (s, 4 H, OCH₂CH₂O), 3.38 (m, 7

H, OCH₃and SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃,

133.0, 129.3 and 128.5 (aromatic CH), 71.8

(CH₂OCH₂CH₂),

71.0

(CH₂OCH₂CH₂),

70.2

(CH₂OCH₂CH₂), 59.1 (OCH₃), 17.2 (SCH₃), 16.6 (SCH₃).

HRMS (ESI) calcd for C₁₅H₂₀O₃S₂[M+Na]⁺: 335.0752;

found: 335.0752.

Typical procedure for the methylation of ketene

dithioacetals 1

Under a nitrogen atmosphere, a mixture of α-oxo ketene

dithioacetal 1 (0.5 mmol), FeCl₃(4 mg, 0.025 mmol),

DABCO·6H₂O (11 mg, 0.05 mmol), and DTBP (219 mg,

1.5 mmol) in benzene (3 mL) was stirred in a 25-mL

sealed tube at 130^oC for 24 h. After cooled to ambient

temperature, the mixture was evaporated all the volatiles

under reduced pressure. The resultant residue was purified

by silica gel column chromatography (eluent: petroleum

o

25 C, TMS) δ 191.9 (Cq, C=O), 172.3 and 139.2 (Cq),

131.0, 128.3 and 128.1 (aromatic CH), 121.1 (Cq), 71.8

(CH₂OCH₂CH₂),

71.4

(CH₂OCH₂CH₂),

69.3

(CH₂OCH₂CH₂), 59.1 (OCH₃), 38.9 and 36.0 (SCH₂CH₂S).

HRMS (ESI) calcd for C₁₅H₁₈O₃S₂[M+H]⁺: 333.0595;

found: 333.0596.

o

3-(1,3-Dithiolan-2-ylidene)-4,5-dimethoxypentan-2-

one (4p): 56 mg, 45% yield; pale yellow liquid. ¹H NMR

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.65 (dd, J = 8.5, 3.9 Hz,

1 H, CHOCH₃), 3.78 (m, 1 H), and 3.39 (dd, J = 10.4 and

3.9 Hz) (1:1 H, CHCH₂OCH₃), 3.34 (s, 3 H, OCH₃), 3.30

(m, 2 H, SCH₂), 3.25 (s, 3 H, OCH₃), 3.17 (m, 2 H, SCH₂),

2.27 (s, 3 H, COCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC,

TMS) δ 193.9 (Cq, C=O), 165.5 and 121.6 (Cq), 81.7

(CHOCH₃), 73.4 (CHCH₂OCH₃), 59.2 (OCH₃), 56.8

ether (60-90 C)/ethyl acetate = 40:1, v/v) to afford the

target product 5.

2-Methyl-3,3-bis(methylthio)-1-phenylprop-2-en-1-

one (5a): 74 mg, 62% yield; pale yellow liquid. ¹H NMR

o

(400 MHz, CDCl₃, 25 C, TMS) δ 7.86 (m, 2 H, aromatic

CH), 7.56 (t, 1 H, aromatic CH), 7.46 (t, 2 H, aromatic

CH), 2.36 (s, 3 H, SCH₃), 2.20 (s, 3 H, C=CCH₃), 2.05 (s,

o

3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

197.5 (Cq, C=O), 143.6 (CSMe), 136.3 (Cq of Ph), 133.5

11

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Advanced Synthesis & Catalysis

(C=CCH₃), 133.3, 129.1 and 128.7 (aromatic CH), 20.1

(C=CCH₃), 17.2 (SCH₃), 16.2 (SCH₃). HRMS (ESI) calcd

for C₁₂H₁₄OS₂[M+H]⁺: 239.0564; found: 2390561.

2-Methyl-3,3-bis(methylthio)-1-(p-tolyl)prop-2-en-1-

2-Benzyl-1-(3-methoxyphenyl)-3,3-bis(methylthio)-

prop-2-en-1-one (7c): 132 mg, 77% yield; pale yellow

liquid.¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.15 (m,

8 H, aromatic CH), 6.98 (m, 1 H, aromatic CH), 4.08 (s, 2

H, PhCH₂), 3.73 (s, 3 H, OCH₃), 2.39 (s, 3 H, SCH₃), 2.01

(s, 3 H, SCH₃).¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ

197.1 (Cq, C=O), 159.6, 146.1, 139.0, 137.8, 136.3 (Cq),

129.2, 128.6, 126.6, 121.8, 119.7 and 112.4 (aromatic CH),

55.4 (OCH₃), 40.9 (PhCH₂), 17.1 (SCH₃), 16.5 (SCH₃).

HRMS (ESI) calcd for C₁₉H₂₀O₂S₂[M+H]⁺: 345.0983;

found: 345.0982.

1

one (5b): 73 mg, 58% yield; pale yellow liquid. H NMR

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.77 (d, J = 8.2 Hz, 2 H,

aromatic CH), 7.26 (m, 2 H, aromatic CH), 2.41 (s, 3 H,

Ph-CH₃), 2.35 (s, 3 H, SCH₃), 2.18 (s, 3 H, C=CCH₃), 2.07

o

(s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS)

δ 197.3 (Cq, C=O), 144.2, 143.9 and 133.6 (Cq), 132.3

(Cq), 129.5 and 129.3 (aromatic CH), 21.8 (Ph-CH₃), 20.1

(C=CCH₃), 17.3 (SCH₃), 16.2 (SCH₃). HRMS (ESI) calcd

for C₁₃H₁₆OS₂[M+H]⁺: 253.0721; found: 253.0724.

2-Benzyl-1-(4-methoxyphenyl)-3,3-bis(methylthio)-

prop-2-en-1-one (7d): 132 mg, 77% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.59 (d,

J = 8.8 Hz, 2 H, aromatic CH), 7.15 (m, 5 H, aromatic CH),

6.79 (d, J = 8.9 Hz, 2 H, aromatic CH), 4.07 (s, 2 H,

PhCH₂), 3.80 (s, 3 H, OCH₃), 2.38 (s, 3 H, SCH₃), 2.06 (s,

1-(4-Chlorophenyl)-2-methyl-3,3-bis(methylthio)-

prop-2-en-1-one (5c): 76 mg, 56% yield 56%; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.79 (d,

J = 8.5 Hz, 2 H, aromatic CH), 7.43 (d, J = 8.5 Hz, 2 H,

aromatic CH), 2.35 (s, 3 H, SCH₃), 2.18 (s, 3 H, C=CCH₃),

o

3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

o

2.05 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

196.1 (Cq, C=O), 163.3, 146.2, 137.8 and 134.9 (Cq),

131.4 (aromatic CH), 130.2 (Cq), 129.1, 128.5, 126.5 and

113.5 (aromatic CH), 55.5 (OCH₃), 40.8 (PhCH₂), 17.1

(SCH₃), 16.4 (SCH₃). HRMS (ESI) calcd for C₁₉H₂₀O₂S₂

[M+H]⁺: 345.0983; found: 345.0979.

TMS) δ 196.3 (Cq, C=O), 142.8, 139.6, 134.8 and 134.3

(Cq), 130.4 and 129.1 (aromatic CH), 20.1 (C=CCH₃),

17.3 (SCH₃), 16.2 (SCH₃). HRMS (ESI) calcd for

C₁₂H₁₃ClOS₂[M+H]⁺: 273.0175; found: 273.0175.

2-Benzyl-3,3-bis(methylthio)-1-(p-tolyl)prop-2-en-1-

1

one (7e): 130 mg, 79% yield; colorless liquid. H NMR

Typical procedure for the CH alkylation of ketene

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.51 (d, J = 8.1 Hz, 2 H,

aromatic CH), 7.20 (m, 4 H, aromatic CH), 7.13 (m, 3 H,

aromatic CH), 4.08 (s, 2 H, PhCH₂), 2.39 (s, 3 H, PhCH₃),

2.34 (s, 3 H, SCH₃), 2.04 (s, 3 H, SCH₃). ¹³C NMR (100

dithioacetals 1 with toluene derivatives 6

Under a nitrogen atmosphere, a mixture of α-oxo ketene

dithioacetal 1 (0.5 mmol), FeCl₃(4 mg, 0.025 mmol),

DABCO·6H₂O (11 mg, 0.05 mmol), and DTBP (219 mg,

1.5 mmol) in toluene derivative 6 (3 mL) was stirred in a

o

MHz, CDCl₃, 25 C, TMS) δ 1967.0 (Cq, C=O), 146.1,

143.5, 137.8, 135.6 and 134.9 (Cq), 129.1, 129.0, 128.5

and 126.5 (aromatic CH), 40.8 (PhCH₂), 21.8 (PhCH₃),

17.1 (SCH₃), 16.4 (SCH₃). HRMS (ESI) calcd for

C₁₉H₂₀OS₂[M+H]⁺: 329.1034; found: 329.1034.

o

25-mL sealed tube at 130 C for 24 h. After cooled to

ambient temperature, the mixture was evaporated all the

volatiles under reduced pressure. The resultant residue was

purified by silica gel column chromatography (eluent:

2-Benzyl-1-(2-fluorophenyl)-3,3-bis(methylthio)-

prop-2-en-1-one (7f): 123 mg,74% yield; yellow liquid.

o

petroleum ether (60-90 C)/ethyl acetate = 100:1, v/v) to

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.38 (m, 1 H,

o

afford the target product 7.

aromatic CH), 7.31 (m, 1 H, aromatic CH), 7.23 (m, 4 H,

aromatic CH), 7.16 (m, 1 H, aromatic CH), 7.03 (m, 2 H,

aromatic CH), 4.12 (s, 2 H, PhCH₂), 2.38 (s, 3 H, SCH₃),

2-Benzyl-3,3-bis(methylthio)-1-phenylprop-2-en-1-

one (7a): 124 mg, 79% yield; white solid, m.p. 60-62 C.

o

¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.59 (d, J = 7.4

Hz, 2 H, aromatic CH), 7.43 (t, 1 H, aromatic CH), 7.30 (t,

2 H, aromatic CH), 7.17 (m, 5 H, aromatic CH), 4.09 (s, 2

H, PhCH₂), 2.39 and 2.00 (s each, 3:3 H, SCH₃). ¹³C NMR

(100 MHz, CDCl₃, 25 ^oC, TMS) δ 197.3 (Cq, C=O), 146.0,

137.7, 137.6 and 136.4 (Cq), 132.7, 129.2, 128.9, 128.6,

128.3 and 126.5 (aromatic CH), 40.86 (PhCH₂), 17.1 and

16.5 (SCH₃). HRMS (ESI) calcd for C₁₈H₁₈OS₂[M+H]⁺:

315.0877; found: 315.0878.

o

1.97 (s, 3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ 193.5 (Cq, C=O), 161.2 (d, J = 256.8 Hz, Cq of

Ph), 146.9 (Cq), 139.4 (d, J = 2.4 Hz, Cq), 138.0 (Cq),

133.6 (d, J = 8.8 Hz, aromatic CH), 130.5, 129.2 and 128.6

(aromatic CH), 127.60 (d, J = 10.3 Hz, Cq), 126.5

(aromatic CH), 123.8 (d, J = 3.7 Hz, aromatic CH), 116.4

(d, J = 22.2 Hz, aromatic CH), 40.4 (PhCH₂), 17.0 (SCH₃),

16.6 (SCH₃). HRMS (ESI) calcd for C₁₈H₁₇FOS₂[M+H]⁺:

333.0783; found: 333.0783.

2-Benzyl-1-(2-methoxyphenyl)-3,3-bis(methylthio)-

prop-2-en-1-one (7b): 123 mg, 75% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.34 (m,

2 H, aromatic CH), 7.21 (m, 4 H, aromatic CH), 7.15 (m, 1

H, aromatic CH), 6.85 (dd, J = 7.8, 5.3 Hz, 2 H, aromatic

CH), 4.08 (s, 2 H, PhCH₂), 3.69 (s, 3 H, OCH₃), 2.35 (s, 3

H, SCH₃), 1.95 (s, 3 H, SCH₃). ¹³C NMR (100 MHz,

2-Benzyl-1-(3-chlorophenyl)-3,3-bis(methylthio)-

prop-2-en-1-one (7g): 130 mg, 75% yield; white solid,

o

m.p. 84-86 C.¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ

7.55 (s, 1 H, aromatic CH), 7.38 (m, 2 H, aromatic CH),

7.18 (m, 6 H, aromatic CH), 4.08 (s, 2 H, PhCH₂), 2.40 (s,

3 H, SCH₃), 2.00 (s, 3 H, SCH₃).¹³C NMR (100 MHz,

o

CDCl₃, 25 C, TMS) δ 195.9 (Cq, C=O), 145.2, 139.5,

CDCl₃, 25 C, TMS) δ 195.8 (Cq, C=O), 158.6, 148.5,

137.5, 137.4 and 134.5 (Cq), 132.4, 129.4, 129.0, 128.7,

126.8 and 126.7 (aromatic CH), 40.9 (PhCH₂), 17.0

(SCH₃), 16.5 (SCH₃). HRMS (ESI) calcd for C₁₈H₁₇ClOS₂

[M+H]⁺: 349.0488; found: 349.0484.

138.6 and 137.2 (Cq), 133.2, 130.8 and 129.2 (aromatic

CH), 128.7 (Cq), 128.4, 126.2, 120.1 and 111.5 (aromatic

CH), 55.5 (OCH₃), 40.3 (PhCH₂), 16.93 (SCH₃), 16.6

(SCH₃). HRMS (ESI) calcd for C₁₉H₂₀O₂S₂[M+H]⁺:

345.0983; found: 345.0982.

Methyl 4-(2-benzyl-3,3-bis(methylthio)acryloyl)ben-

1

zoate (7h): 136 mg, 73% yield; pale yellow liquid. H

12

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

o

NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.94 (d, J = 8.5

Hz, 2 H, aromatic CH), 7.56 (d, J = 8.4 Hz, 2 H, aromatic

CH), 7.16 (m, 5 H, aromatic CH), 4.10 (s, 2 H, PhCH₂),

3.89 (s, 3 H, OCH₃), 2.39 (s, 3 H, SCH₃), 1.94 (s, 3 H,

2-(4-Methoxybenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7m): 101 mg, 59% yield; white solid,

m.p. 87-89 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ

7.62 (m, 2 H, aromatic CH), 7.46 (t, 1 H, aromatic CH),

7.32 (dd, J = 18.6 and 11.0 Hz, 2 H, aromatic CH), 7.11 (d,

J = 8.6 Hz, 2 H, aromatic CH), 6.75 (d, J = 8.6 Hz, 2 H,

aromatic CH), 4.05 (s, 2 H, PhCH₂), 3.74 (s, 3 H, OCH₃),

2.41 (s, 3 H, SCH₃), 2.02 (s, 3 H, SCH₃). ¹³C NMR (100

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 196.7

o

(Cq, C=O), 166.4 (Cq, C=O), 145.4, 141.6, 137.9 and

137.5 (Cq of Ph), 133.1 (Cq), 129.4, 129.1, 128.7, 128.5

and 126.7 (aromatic CH), 52.5 (OCH₃), 41.0 (PhCH₂), 16.9

(SCH₃), 16.5 (SCH₃). HRMS (ESI) calcd for C₂₀H₂₀O₃S₂

[M+H]⁺: 373.0932; found: 373.0931.

o

MHz, CDCl₃, 25 C, TMS) δ 197.4 (Cq, C=O), 158.2,

146.4, 137.6 and 135.8 (Cq), 132.7 and 130.1 (aromatic

CH), 129.8 (Cq), 128.9, 128.3 and 114.0 (aromatic CH),

55.3 (OCH₃), 39.9 (PhCH₂), 17.0 (SCH₃), 16.5 (SCH₃).

HRMS (ESI) calcd for C₁₉H₂₀O₂S₂[M+H]⁺: 345.0983;

found: 345.0984.

3,3-Bis(methylthio)-1-phenyl-2-((p-tolyloxy)methyl)-

prop-2-en-1-one (7m): 30 mg, 17% yield; pale yellow

2-(2-Methylbenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7i): 142 mg, 87% yield; colorless solid,

m.p. 71-73 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ

7.64 (d, J = 7.4 Hz, 2 H, aromatic CH), 7.45 (t, 1 H,

aromatic CH), 7.32 (t, 2 H, aromatic CH), 7.16 (m, 1 H,

aromatic CH), 7.03 (m, 3 H, aromatic CH), 4.08 (s, 2 H,

PhCH₂), 2.40 (s, 3 H, SCH₃), 2.26 (s, 3 H, Ph-CH₃), 2.08 (s, liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.92 (m,

3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

196.9 (Cq, C=O), 146.0, 137.1, 136.5, 135.7 and 135.1

(Cq), 132.8, 130.3, 129.7, 128.8, 128.3, 126.7 and 126.1

(aromatic CH), 37.8 (PhCH₂), 20.0 (Ph-CH₃), 17.3 (SCH₃),

16.5 (SCH₃). HRMS (ESI) calcd for C₁₉H₂₀OS₂[M+H]⁺:

329.1034; found: 329.1029.

2 H, aromatic CH), 7.54 (t, 1 H, aromatic CH), 7.44 (t, 2 H,

aromatic CH), 7.02 (d, J = 8.4 Hz, 2 H, aromatic CH), 6.75

(d, J = 8.5 Hz, 2 H, aromatic CH), 5.01 (s, 2 H, PhOCH₂),

2.39 (s, 3 H, SCH₃), 2.25 (s, 3 H, Ph-CH₃), 2.11 (s, 3 H,

o

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 196.3

(Cq, C=O), 156.3, 142.9, 141.4 and 137.7 (Cq), 133.0

(aromatic CH), 130.5 (Cq), 129.9, 129.3, 128.5 and 114.9

(aromatic CH), 68.3 (PhOCH₂), 20.6 (PhCH₃), 17.2

2-(3-Methylbenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7j): 140 mg, 85% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.62 (m, (SCH₃), 16.7 (SCH₃). HRMS (ESI) calcd for C₁₉H₂₀O₂S₂

2 H, aromatic CH), 7.44 (t, 1 H, aromatic CH), 7.32 (t, 2 H,

aromatic CH), 7.09 (t, 1 H, aromatic CH), 6.97 (m, 3 H,

aromatic CH), 4.08 (s, 2 H, PhCH₂), 2.40 (s, 3 H, SCH₃),

2.23 (s, 3 H, Ph-CH₃), 2.02 (s, 3 H, SCH₃). ¹³C NMR (100

[M+Na]⁺: 367.0802; found: 367.0803.

2-(4-(tert-Butyl)benzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7n): 146 mg, 79% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.29 (m,

9 H, aromatic CH), 4.03 (s, 2 H, PhCH₂), 2.37 (s, 3 H,

SCH₃), 1.98 (s, 3 H, SCH₃), 1.22 (s, 9 H, C(CH₃)₃). ¹³C

o

MHz, CDCl₃, 25 C, TMS) δ 197.3 (Cq, C=O), 145.9,

138.0, 137.5, 137.4 and 136.1 (Cq),132.6, 129.9, 128.9,

128.3, 128.1, 127.2 and 126.0 (aromatic CH), 40.7

(PhCH₂), 21.3 (Ph-CH₃), 17.0 (SCH₃), 16.4 (SCH₃).

HRMS (ESI) calcd for C₁₉H₂₀OS₂[M+H]⁺: 329.1034;

found: 329.1035.

2-(4-Methylbenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7k): 133 mg, 81% yield; white solid,

m.p. 87-89 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ

7.62 (d, J = 7.3 Hz, 2 H, aromatic CH), 7.45 (t, 1 H,

aromatic CH), 7.31 (dd, J = 20.4 and 12.8 Hz, 2 H,

aromatic CH), 7.04 (dd, J = 29.4 and 7.9 Hz, 4 H, aromatic

CH), 4.06 (s, 2 H, PhCH₂), 2.39 (s, 3 H, SCH₃), 2.26 (s, 3

H, Ph-CH₃), 2.01 (s, 3 H, SCH₃). ¹³C NMR (100 MHz,

o

NMR (100 MHz, CDCl₃, 25 C, TMS) δ 197.5 (Cq, C=O),

149.3, 146.4, 137.6 and 135.7 and 134.6 (Cq), 132.6, 129.0,

128.8, 128.1 and 125.5 (aromatic CH), 40.3 (PhCH₂), 34.4

(C(CH₃)₃), 31.4 (C(CH₃)₃), 17.0 (SCH₃), 16.5 (SCH₃).

HRMS (ESI) calcd for C₂₂H₂₆OS₂[M+H]⁺: 371.1503;

found: 371.1497.

2-(2-Chlorobenzyl)-3,3-bis(methylthio)-1-phenylprop

-2-en-1-one (7o): 138 mg, 79% yield; white solid, m.p. 92-

94 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.69 (d,

J = 7.5 Hz, 2 H, aromatic CH), 7.43 (t, 1 H, aromatic CH),

7.27 (m, 4 H, aromatic CH), 7.05 (m, 2 H, aromatic CH),

4.19 (s, 2 H, PhCH₂), 2.37 (s, 3 H, SCH₃), 2.07 (s, 3 H,

o

CDCl₃, 25 C, TMS) δ 197.3 (Cq, C=O), 146.2, 137.6,

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 196.5

136.1, 135.9 and 134.6 (Cq), 132.6 (s), 129.2, 129.0, 128.9

and 128.2 (aromatic CH), 40.4 (PhCH₂), 21.1 (Ph-CH₃),

17.0 (SCH₃), 16.4 (SCH₃). HRMS (ESI) calcd for

C₁₉H₂₀OS₂[M+H]⁺: 329.1034; found: 329.10354.

(Cq, C=O), 144.3, 137.0, 136.5, 135.2 and 134.2 (Cq),

132.9, 131.3, 129.4, 128.8, 128.3, 128.1 and 126.90

(aromatic CH), 38.0 (PhCH₂), 17.2 (SCH₃), 16.5 (SCH₃).

HRMS (ESI) calcd for C₁₈H₁₇ClOS₂[M+H]⁺: 349.0488;

found: 349.0490.

2-(3,5-Dimethylbenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7l): 137 mg, 80% yield; white solid, m.p.

88-89 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.63

(d, J = 7.5 Hz, 2 H, aromatic CH), 7.45 (t, 1 H, aromatic

CH), 7.31 (dd, J = 20.2, 12.6 Hz, 2 H, aromatic CH), 6.77

(d, J = 8.7 Hz, 3 H, aromatic CH), 4.02 (s, 2 H, PhCH₂),

2.40 (s, 3 H, SCH₃), 2.19 (s, 6 H, Ph-CH₃), 2.02 (s, 3 H,

2-(3-Bromobenzyl)-3,3-bis(methylthio)-1-phenyl-

prop-2-en-1-one (7p): 135 mg, 69% yield; pale yellow

liquid. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.63 (m,

2 H), 7.46 (m, 1 H, aromatic CH), 7.36 (dd, J = 12.3 and

4.5 Hz, 3 H, aromatic CH), 7.27 (m, 1 H, aromatic CH),

7.07 (m, 2 H, aromatic CH), 4.05 (s, 2 H, PhCH₂), 2.39 (s,

3 H, SCH₃), 2.04 (s, 3 H, SCH₃). ¹³C NMR (100 MHz,

o

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 197.4

o

(Cq, C=O), 146.2, 137.9, 137.6, 137.4 and 135.9 (Cq),

132.6, 129.0, 128.2, 128.1 and 127.0 (aromatic CH), 40.7

(PhCH₂), 21.3 (Ph-CH₃), 17.0 (SCH₃), 16.4 (SCH₃).

HRMS (ESI) calcd for C₂₀H₂₂OS₂[M+H]⁺: 343.1194;

found: 343.1194.

CDCl₃, 25 C, TMS) δ 196.9 (Cq, C=O), 144.6, 140.0,

137.6 and 137.3 (Cq), 132.8, 132.1, 130.1, 129.6, 128.9,

128.4 and 127.8 (aromatic CH), 122.5 (Cq), 40.2 (PhCH₂),

17.1 (SCH₃), 16.5 (SCH₃). HRMS (ESI) calcd for

C₁₈H₁₇BrOS₂[M+H]⁺: 392.9982; found: 392.9988.

13

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

o

1

o

2-(4-Fluorobenzyl)-3,3-bis(methylthio)-1-phenylprop

114 C. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.52

(m, 3 H, aromatic CH), 7.35 (m, 5 H, aromatic CH), 7.20

(d, J = 7.3 Hz, 2 H, aromatic CH), 4.14 (s, 2 H, PhCH₂),

3.45 (m, 4 H, SCH₂CH₂S). ¹³C NMR (100 MHz, CDCl₃, 25

^oC, TMS) δ 193.6 (Cq, C=O), 164.4, 139.8, 138.8 (Cq of

Ph), 130.6, 128.5, 128.2, 128.1, 127.6 and 126.2 (aromatic

CH), 122.9 (Cq), 40.4 (PhCH₂), 39.2 and 36.4

(SCH₂CH₂S). HRMS (ESI) calcd for C₁₈H₁₆OS₂[M+H]⁺:

313.0721; found: 313.0728.

-2-en-1-one (7q): 113 mg, 69% yield; pale yellow liquid.

o

¹H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.58 (m, 2 H,

aromatic CH), 7.45 (t, 1 H, aromatic CH), 7.32 (t, 2 H,

aromatic CH), 7.14 (dd, J = 8.5 and 5.5 Hz, 2 H, aromatic

CH), 6.88 (dd, J = 12.1 and 5.3 Hz, 2 H, aromatic CH),

4.04 (s, 2 H, PhCH₂), 2.38 (s, 3 H, SCH₃), 2.01 (s, 3 H,

o

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 197.2

(Cq, C=O), 161.0 (d, J = 244.6 Hz, Cq of Ph), 145.5, 137.5

and 136.7 (Cq), 133.5 (d, J = 3.2 Hz, Cq of Ph), 132.8

(aromatic CH), 130.6 (d, J = 7.9 Hz, aromatic CH), 128.88

and 128.35 (aromatic CH), 115.4 (d, J = 21.3 Hz, aromatic

CH), 39.9 (PhCH₂), 17.0 (SCH₃), 16.4 (SCH₃). HRMS

(ESI) calcd for C₁₈H₁₇FOS₂[M+H]⁺: 333.0783; found:

333.0783.

2-(Bis(methylthio)methylene)-1,3-diphenylbutan-1-

one (7w): 90 mg, 55% yield; yellow solid, m.p. 62-64^oC.

¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.61 (d, J = 7.4

Hz, 2 H, aromatic CH), 7.41 (t, 1 H, aromatic CH), 7.27

(dd, J = 15.2 and 7.6 Hz, 4 H, aromatic CH), 7.15 (t, 2 H,

aromatic CH), 7.07 (t, 1 H, aromatic CH), 4.74 (q, J = 7.3

Hz, 1 H, CHCH₃), 2.32 (s, 3 H, SCH₃), 2.00 (s, 3 H, SCH₃),

1.49 (d, J = 7.3 Hz, 3 H, CHCH₃). ¹³C NMR (100 MHz,

2-(4-Acetylbenzyl)-3,3-bis(methylthio)-1-phenylprop

-2-en-1-one (7r): 92 mg, 51% yield; pale yellow liquid. ¹H

o

NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.75 (d, J = 8.3

CDCl₃, 25 C, TMS) δ 196.0 (Cq, C=O), 150.9, 142.8,

Hz, 2 H, aromatic CH), 7.55 (m, 2 H, aromatic CH), 7.40

(dd, J = 10.5 and 4.3 Hz, 1 H, aromatic CH), 7.25 (m, 4 H,

aromatic CH), 4.08 (s, 2 H, PhCH₂), 2.48 (s, 3 H, SCH₃),

2.35 (s, 3 H,COCH₃), 1.97 (s, 3 H, SCH₃). ¹³C NMR (100

137.6 and 133.3 (Cq), 132.7, 129.1, 128.3, 128.2, 128.1,

and 126.5 (aromatic CH), 43.8 (PhCH), 19.4 (CHCH₃),

17.1 (SCH₃), 16.4 (s). HRMS (ESI) calcd for C₁₉H₂₀OS₂

[M+H]⁺: 329.1034; found: 329.1035.

o

MHz, CDCl₃, 25 C, TMS) δ 197.9 (Cq, C=O), 196.9 (Cq,

3-(Bis(methylthio)methylene)-4-phenylpentan-2-one

1

C=O), 144.3 (CSMe), 143.5, 138.0 and 137.4 (Cq of Ph),

135.5 (C=CCH₂), 132.9, 129.4, 128.9, 128,8 and 128.4

(aromatic CH), 40.7 (PhCH₂), 26.7 (COCH₃), 17.2 (SCH₃),

16.5 (SCH₃). HRMS (ESI) calcd for C₂₀H₂₀O₂S₂[M+H]⁺:

357.0983; found: 357.0987.

(7x): 87 mg, 59% yield; white solid, m.p. 65-67^oC. H

o

NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.25 (m, 5 H,

aromatic CH), 4.65 (q, J = 7.2 Hz, 1 H, C=CCH), 2.33 and

2.26 (s each, 3:3 H, SCH₃and COCH₃), 1.86 (s, 3 H,

SCH₃), 1.49 (d, J = 7.2 Hz, 3 H, CHCH₃). ¹³C NMR (100

o

3-Benzyl-4,4-bis(methylthio)but-3-en-2-one (7s): 96

MHz, CDCl₃, 25 C, TMS) δ 204.4 (Cq, C=O), 155.3,

1

mg, 76% yield; colourless liquid. H NMR (400 MHz,

142.1 and 130.3 (Cq), 128.6, 127.8 and 126.8 (aromatic

CH), 42.7 (PhCH₂), 32.2 (COCH₃), 18.2 (CHCH₃), 17.4

(SCH₃), 16.5 (SCH₃). HRMS (ESI) calcd for C₁₄H₁₈OS₂

[M+H]⁺: 267.0877; found: 267.0874.

CDCl₃, 25 ^oC, TMS) δ 7.34 (t, 2 H, aromatic CH), 7.25 (m,

3 H, aromatic CH), 4.05 (s, 2 H, PhCH₂), 2.42 and 2.39 (s

each, 3:3 H, SCH₃and COCH₃), 2.21 (s, 3 H, SCH₃).¹³C

NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ 204.1 (Cq, C=O),

148.1, 138.0 and 136.5 (Cq), 128.7, 128.6 and 126.5

(aromatic CH), 40.0 (PhCH₂), 31.1 (COCH₃), 17.5 (SCH₃),

16.7 (SCH₃). HRMS (ESI) calcd for C₁₃H₁₆OS₂[M+H]⁺:

253.0721; found: 253.0723.

2-(1,4-Dioxan-2-yl)-3-(methylthio)-1,3-diphenylprop-

2-en-1-one (9a): 97 mg, 57% yield; white solid, m.p. 137-

o

1

o

139 C. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ for

(E)-isomer: 7.62 (m, 2 H, aromatic CH), 7.49 (m, 2 H,

aromatic CH), 7.31 (m, 1 H, aromatic CH), 7.18 (t, 2 H,

aromatic CH), 7.04 (m, 3 H, aromatic CH), 5.10 (dd, J =

10.2 and 2.7 Hz, 1 H, OCHCH₂O), 4.06 (dd, J = 11.5 and

2.7 Hz) and 3.65 (m) (1:5 H, CH₂OCH₂CH₂O), 1.85 (s, 3

H, SCH₃); for (Z)-isomer: 8.11 (m, 2 H, aromatic CH),

7.57 (t, 1 H, aromatic CH), 7.49 (m, 3 H, aromatic CH),

7.40 (m, 1 H, aromatic CH), 7.04 (m, 3 H, aromatic CH),

4.35 (dd, J = 10.0 and 2.9 Hz, 1 H, OCHCH₂O), 3.65 (m, 6

H, CH₂OCH₂CH₂O), 1.62 (s, 3 H, SCH₃). ¹³C NMR (100

3-(4-Methylbenzyl)-4,4-bis(methylthio)but-3-en-2-

1

one (7t): 117 mg, 88% yield; pale yellow liquid. H NMR

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 7.06 (q, J = 8.1 Hz, 4 H,

aromatic CH), 3.93 (s, 2 H, PhCH₂), 2.35 (s, 3 H, SCH₃),

2.32 and 2.30 (s each, 3:3 H, Ph-CH₃and COCH₃), 2.15 (s,

o

3 H, SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

204.3 (Cq, C=O), 148.5, 136.1, 136.0 and 134.8 (Cq),

129.4 and 128.5 (aromatic CH), 39.6 (PhCH₂), 31.2

(COCH₃), 21.1 (Ph-CH₃), 17.5 (SCH₃), 16.7 (SCH₃).

HRMS (ESI) calcd for C₁₄H₁₈OS₂[M+H]⁺: 267.0877;

found: 267.0877.

3-(3,5-Dimethylbenzyl)-4,4-bis(methylthio)but-3-en-

2-one (7u): 122 mg, 87% yield; pale yellow solid, m.p. 53-

54 ^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 6.83 (s,

o

MHz, CDCl₃, 25 C, TMS) δ for (E)-isomer: 197.1 (Cq,

C=O) [190.0 for (Z)-isomer], 143.2 (Cq) [141.62 for (Z)-

isomer], 137.9 (Cq) [137.8 for (Z)-isomer], 136.0 (Cq)

[136.2 and 135.6 for (Z)-isomer], 132.6, 129.8, 129.3,

128.4, 128.1 and 127.8 (aromatic CH) [133.1, 129.4, 129.0,

128.8, 128.9 and 128.5 for (Z)-isomer], 76.6 (OCHCH₂O)

1 H, aromatic CH), 6.76 (s, 2 H, aromatic CH), 3.91 (s, 2 H, [76.3 for (Z)-isomer], 69.2 (s), 68.6 (CH₂OCH₂CH₂O)

PhCH₂), 2.36 and 2.33 (s each, 3:3 H, SCH₃and Ph-CH₃),

2.27 (s, 6 H, COCH₃and Ph-CH₃), 2.15 (s, 3 H, SCH₃).¹³C

NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ 204.4 (Cq, C=O),

148.5, 138.2, 137.8 and 136.1 (Cq), 128.3 and 126.5

(aromatic CH), 40.0 (PhCH₂), 31.3 (COCH₃), 21.4 (Ph-

CH₃), 17.5 (SCH₃), 16.8 (SCH₃). HRMS (ESI) calcd for

C₁₅H₂₀OS₂[M+H]⁺: 281.1034; found: 281.1037.

[69.2 for (Z)-isomer], 67.0 and 66.2 (CH₂OCH₂CH₂O)

[66.5 and 65.9 for (Z)-isomer], 15.6 (SCH₃) [15.4 for (Z)-

isomer]. HRMS (ESI) calcd for C₂₀H₂₀O₃S [M+H]⁺:

341.1211; found: 341.1211.

3-(1,4-Dioxan-2-yl)-4-(methylthio)-4-phenylbut-3-en-

o

2-one (9b): 99 mg, 71% yield; white solid, m.p. 73-75 C.

¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ for (E)-isomer:

7.39 (m, 3 H, aromatic CH), 7.27 (m, 2 H, aromatic CH),

4.18 (dd, J = 10.3 and 2.7 Hz, 1 H, OCHCH₂O), 3.87, 3.67

2-(1,3-Dithiolan-2-ylidene)-1,3-diphenylpropan-1-

one (7v): 106 mg, 68% yield; pale yellow solid, m.p. 112-

14

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Advanced Synthesis & Catalysis

and 3.51 (m each, 2:2:2 H, CH₂OCH₂CH₂O), 2.54 (s, 3 H,

purified by silica gel column chromatography (eluent:

SCH₃), 1.79 (s, 3 H, COCH₃); for (Z)-isomer: 7.39 (m, 3 H, dichloromethane) to afford the target product.

aromatic CH), 7.27 (m, 2 H, aromatic CH), 4.95 (dd, J =

9.9 and 3.0 Hz, 1 H, OCHCH₂O), 3.87, 3.67 and 3.51 (m

each, 2:2:2 H, CH₂OCH₂CH₂O), 1.86 (s, 3 H, SCH₃), 1.76

4-(1,4-Dioxan-2-yl)-5-(methylthio)-3-phenyl-1H-

pyrazole (12a): 52 mg, 95% yield; white solid, m.p. 149-

1

o

151^oC. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.45

(m, 5 H, aromatic CH), 4.72 (dd, J = 10.7 and 2.8 Hz, 1 H,

OCHCH₂O), 3.99 (t) and 3.89 (d, J = 11.3 Hz) (1:1 H,

OCHCH₂O), 3.80 (m), 3.70 (d, J = 5.8 Hz) and 3.60 (dd, J

= 11.7 and 2.7 H)(1:2:1 H, OCH₂CH₂O), 2.44 (s, 3 H,

SCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ 145.8,

144.8 and 130.1 (Cq), 129.0, 128.8 and 128.7 (aromatic

CH), 114.5 (Cq), 70.9 (OCHCH₂O), 69.0 (OCHCH₂O),

67.4 and 66.2 (OCH₂CH₂O), 16.7 (SCH₃). HRMS (ESI)

calcd for C₁₄H₁₆N₂O₂S [M+H]⁺: 277.1011; found:

277.1008.

o

(s, 3 H, COCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ for (E)-isomer: 203.3 (Cq, C=O) [203.8 for (Z)-

isomer], 141.8 (Cq) [142.1 for (Z)-isomer], 137.4 (Cq)

[138.6 for (Z)-isomer], 135.4 (Cq) [136.3 for (Z)-isomer],

128.7, 128.6 and 128.5 (aromatic CH) [129.3, 128.8 and

128.7 for (Z)-isomer], 75.7 (OCHCH₂O) [76.6 for (Z)-

isomer], 68.5 (OCHCH₂O) [67.9 for (Z)-isomer], 66.5 and

65.8 (OCH₂CH₂O) [66.8 and 66.0 for (Z)-isomer], 31.9

(COCH₃) [32.0 for (Z)-isomer], 15.4 (SCH₃). HRMS (ESI)

calcd for C₁₅H₁₈O₃S [M+H]⁺: 279.1055; found: 279.1048.

4-(4-Chlorophenyl)-3-(1,4-dioxan-2-yl)-4-(methyl-

4-(1,4-Dioxan-2-yl)-3-methyl-5-(methylthio)-1H-

pyrazole (12b): 41 mg, 95% yield; white solid, m.p. 88-90

thio)but-3-en-2-one (9c): 117 mg, 75% yield; white solid,

o

1

o

1

o

m.p. 86-88 C. H NMR (400 MHz, CDCl₃, 25 C, TMS)

for (E)-isomer: 7.37 (d, J = 8.3 Hz, 2 H, aromatic CH),

7.21 (d, J = 8.3 Hz, 2 H, aromatic CH), 4.08 (dd, J = 10.3

and 2.8 Hz, 1 H, OCHCH₂O), 3.86 (dd, J = 11.4 and 2.8

Hz) and 3.75 (m) (1:1 H, CH₂OCH₂CH₂O), 3.54 (m, 4 H,

OCH₂CH₂O), 2.48 (s, 3 H, SCH₃), 1.76 (s, 3 H, COCH₃);

for (Z)-isomer: 7.30 (d, J = 8.4 Hz, 2 H, aromatic CH),

7.16 (d, J = 8.4 Hz, 2 H, aromatic CH), 4.89 (dd, J = 10.1

^oC. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ 7.72 (s, 1

H, NH), 4.67 (dd, J = 10.4 and 3.0 Hz, 1 H, OCHCH₂O),

3.75 (m, 6 H, OCH₂CH₂OCH₂), 2.40 (s, 3 H, SCH₃), 2.33

(s, 3 H, CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 ^oC, TMS) δ

143.5, 141.2 and 115.2 (Cq), 71.4 (OCHCH₂O), 70.0

(OCHCH₂O), 67.4 and 66.4 (OCH₂CH₂O), 17.5 (SCH₃),

11.1 (CH₃). HRMS (ESI) calcd for C₉H₁₄N₂O₂S [M+H]⁺:

215.0854; found: 215.0851.

and 2.9 Hz,

1

H, OCHCH₂O), 3.75 (m,

2

H,

3-Cyclopropyl-4-(1,4-dioxan-2-yl)-5-(methylthio)-

1H-pyrazole (12c): 46 mg, 96% yield; white solid, m.p.

CH₂OCH₂CH₂O), 3.54 (m, 4 H, OCH₂CH₂O), 1.82 (s, 3 H,

SCH₃), 1.78 (s, 3 H, COCH₃). ¹³C NMR (100 MHz, CDCl₃, 128-130 C. H NMR (400 MHz, CDCl₃, 25 C, TMS) δ

o

1

o

25 ^oC, TMS) δ for (E)-isomer: 203.4 (Cq, C=O) [203.8 for

(Z)-isomer], 139.8 (Cq) [140.5], 138.4 and 134.8 (Cq)

[139.9 and 135.0 for (Z)-isomer], 134.0 (Cq) [134.8 for

(Z)-isomer] , 130.1 and 129.1 (aromatic CH) [130.8 and

129.0 for (Z)-isomer], 75.6 (OCHCH₂O) [76.5 for (Z)-

isomer], 68.5 (OCHCH₂O) [68.0 for (Z)-isomer], 66.6 and

65.9 (OCH₂CH₂O) [66.9 and 66.1 for (Z)-isomer], 31.9

8.26 (s, 1 H, NH), 4.71 (dd, J = 10.6 and 2.7 Hz, 1 H,

OCHCH₂O), 3.75 (m, 6 H, OCH₂CH₂OCH₂), 2.35 (s, 3 H,

SCH₃), 1.94 (m, 1 H, CH₂CHCH₂), 0.82 and 0.63 (m each,

o

3:1 H, CH₂CHCH₂). ¹³C NMR (100 MHz, CDCl₃, 25 C,

TMS) δ 147.2, 142.9 and 115.9 (Cq of pyrazole), 71.3

(OCHCH₂O), 69.9 (OCHCH₂O), 67.4 and 66.4

(OCH₂CH₂O), 17.3 (SCH₃), 7.5 (CH₂CHCH₂), 6.7 and 6.6

(COCH₃) [32.3 for (Z)-isomer], 15.60 (SCH₃). HRMS (ESI) (CH₂CHCH₂). HRMS (ESI) calcd for C₁₁H₁₆N₂O₂S

calcd for C₁₅H₁₈ClO₃S [M+H]⁺: 313.0665; found:

313.0670.

[M+H]⁺: 241.1011; found: 241.1012.

4-Benzyl-3-methyl-5-(methylthio)-1H-pyrazole (12d):

1

3-(1,4-Dioxan-2-yl)-4,4-diphenylbut-3-en-2-one (11):

38 mg, 87% yield; colourless liquid. H NMR (400 MHz,

o

1

o

16 mg, 10% yield; white solid, m.p. 94-96 C. H NMR

CDCl₃, 25 C, TMS) δ 8.65 (s, 1 H, NH), 7.21 (m, 5 H,

o

(400 MHz, CDCl₃, 25 C, TMS) δ 7.31 (m, 3 H, aromatic

aromatic CH), 3.82 (s, 2 H, PhCH₂), 2.35 (s, 3 H, SCH₃),

o

CH), 7.20 (m, 5 H, aromatic CH), 7.17 (m, 2 H, aromatic

2.19 (s, 3 H, CH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C,

CH), 4.39 (dd, J = 10.2 and 2.7 Hz, 1 H, OCHCH₂O), 3.90

TMS) δ 142.7, 141.7 and 140.5 (Cq), 128.5, 128.3 and

(dd, J = 11.5 and 10.3 Hz) and 3.69 (d, J = 10.4 Hz) (1:1 H, 126.1 (aromatic CH), 118.3 (Cq), 29.3 (PhCH₂), 17.6

OCHCH₂O), 3.55 (m, 4 H, OCH₂CH₂O), 1.86 (s, 3 H,

(SCH₃), 10.9 (CH₃). HRMS (ESI) calcd for C₁₂H₁₄N₂S

o

COCH₃). ¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ

[M+H]⁺: 219.0956; found: 219.0956.

206.9 (Cq, C=O), 144.9 (CSMe), 140.3 and 139.8 (Cq of

Ph), 138.5 (C=CCH), 129.4, 129.0, 128.8, 128.7, 128.6 and

128.2 (aromatic CH), 77.0 (OCHCH₂O), 68.9

(CH₂OCH₂CH₂O), 66.6 and 66.1 (OCH₂CH₂O), 32.7

(COCH₃). HRMS (ESI) calcd for C₂₀H₂₀O₃[M+H]⁺:

309.1491; found: 309.1491.

Typical procedure for the synthesis of isoxazoles 13

A mixture of 3 (50 mg, 0.2 mmol), NH₂OH·HCl (83 mg,

1.2 mmol), and KOH (79 mg, 1.2 mmol, 85%) in EtOH (2

mL) was stirred in a 10-mL sealed tube at 120^oC for 24 h.

After cooled to ambient temperature, the mixture was

evaporated all the volatiles under reduced pressure. The

resultant residue was purified by silica gel column

Typical procedure for the synthesis of trisubstituted

pyrazoles 12

o

chromatography (eluent: petroleum ether (60-90 C)/ethyl

A mixture of 3 or 7 (0.2 mmol) and NH₂NH₂·H₂O (114

mg, 2.0 mmol, aq 85%) in toluene (2 mL) was stirred in a

10-mL sealed tube at 120^oC for 24 h. After cooled to

ambient temperature, the mixture was evaporated all the

volatiles under reduced pressure. The resultant residue was

acetate = 10:1, v/v) to afford the target product.

4-(1,4-Dioxan-2-yl)-3-methyl-5-(methylthio)isoxazole

1

(13a): 24 mg, 56% yield; colorless liquid. H NMR (400

MHz, CDCl₃, 25 ^oC, TMS) δ 4.53 (dd, J = 8.0 and 5.5 Hz,

1 H, OCHCH₂O), 3.76 (m, 6 H, OCH₂CH₂OCH₂), 2.55 (s,

3 H, SCH₃), 2.30 (s, 3 H, CH₃C=N). ¹³C NMR (100 MHz,

15

10.1002/adsc.201700654

Advanced Synthesis & Catalysis

o

CDCl₃, 25 C, TMS) δ 163.7, 159.8 and 112.6 (Cq of

Chem.-Eur. J. 2010, 16, 5844;d) Y. Ashida, Y. Sato,

T. Ueno, K. Suzuki, K.-I. Kai, H. Nakatsuji, Y.

Tanabe, Chem.-Eur. J. 2015, 21, 5934.

isoxazole), 70.1 (OCHCH₂O), 69.3 (OCHCH₂O), 67.2 and

66.4 (OCH₂CH₂O), 14.9 (SCH₃), 11.1 (CH₃C=N). HRMS

(ESI) calcd for C₉H₁₃NO₃S [M+H]⁺: 216.0694; found:

216.0690.

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3-Cyclopropyl-4-(1,4-dioxan-2-yl)-5-(methylthio)iso-

xazole (13b): 26 mg, 54% yield; white solid, m.p. 71-73

^oC. ¹H NMR (400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.65 (dd, J

= 10.4 and 2.9 Hz, 1 H, OCHCH₂O), 3.78 (m, 6 H,

OCH₂CH₂OCH₂), 2.55 (s, 3 H, SCH₃), 1.94 (m, 1 H,

CH₂CHCH₂), 1.08 and 0.94 (m each, 1:3 H, CH₂CHCH₂).

¹³C NMR (100 MHz, CDCl₃, 25 C, TMS) δ 165.0, 163.7

o

and 113.1 (Cq of isoxazole), 70.1 (OCHCH₂O), 69.5

(OCHCH₂O), 67.3 and 66.4 (OCH₂CH₂O), 14.9 (SCH₃),

8.5 (CH₂CHCH₂), 7.3 and 6.5 (CH₂CHCH₂). HRMS (ESI)

calcd for C₁₁H₁₅NO₃S [M+H]⁺: 242.0851; found: 242.0854.

3-Methyl-5-(methylthio)-4-(tetrahydrofuran-2-yl)iso-

xazole (13c): 22 mg, 55% yield; colorless liquid. ¹H NMR

(400 MHz, CDCl₃, 25 ^oC, TMS) δ 4.74 (dd, J = 8.6 and 6.7

Hz, 1 H, OCHCH₂), 4.02 and 3.84 (m each,1:1 H,

OCH₂CH₂), 2.55 (s, 3 H, SCH₃), 2.25 (s, 3 H, CH₃C=N),

2.08 and 1.85 (m each, 3:1 H, OCHCH₂CH₂). ¹³C NMR

o

(100 MHz, CDCl₃, 25 C, TMS) δ 162.2, 159.7 and 116.6

(Cq of isoxazole), 72.5 (OCHCH₂), 68.6 (OCH₂CH₂), 32.1

and 26.6 (OCHCH₂CH₂), 15.1 (SCH₃), 11.0 (CH₃C=N).

HRMS (ESI) calcd for C₉H₁₃NO₂S [M+H]⁺: 200.0745;

found: 200.0741.

Acknowledgements

We are grateful to the National Natural Science

Foundation of China (21472185) and the National Basic

Research Program of China (2015CB856600) for support

of this research.

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Advanced Synthesis & Catalysis

FULL PAPER

Iron-Mediated Oxidative CH Alkylation of S,S-

Functionalized

Internal

Olefins

via

C(sp²)H/C(sp³)H Cross-Coupling

Adv. Synth. Catal. Year, Volume, Page – Page

Quannan Wang, Jiang Lou, Ping Wu, Kaikai Wu,

and Zhengkun Yu*

18

Article Doi

Iron-Mediated Oxidative C–H Alkylation of S,S-Functionalized Internal Olefins via C(sp2)–H/C(sp3)–H Cross-Coupling

DOI: 10.1002/adsc.201700654

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