Chemo-enzymatic synthesis and glycosidase inhibitory properties of DAB and LAB derivatives

Organic &

Biomolecular Chemistry

View Article Online

View Journal | View Issue

PAPER

Chemo-enzymatic synthesis and glycosidase inhibitory

properties of DAB and LAB derivatives†

Cite this: Org. Biomol. Chem., 2013, 11,

2005

Alda Lisa Concia,^aLivia Gómez,^aJordi Bujons,^aTeodor Parella,^bCristina Vilaplana,^c

Pere Joan Cardona,^cJesús Joglar^aand Pere Clapés*^a

A chemo-enzymatic strategy for the preparation of 2-aminomethyl derivatives of (2R,3R,4R)-2-(hydroxy-

methyl)pyrrolidine-3,4-diol (also called 1,4-dideoxy-1,4-imino-^D-arabinitol, DAB) and its enantiomer LAB

is presented. The synthesis is based on the enzymatic preparation of DAB and LAB followed by the chemi-

cal modiﬁcation of their hydroxymethyl functionality to aﬀord diverse 2-aminomethyl derivatives. This

strategy leads to novel aromatic, aminoalcohol and 2-oxopiperazine DAB and LAB derivatives. The com-

pounds were preliminarily explored as inhibitors of a panel of commercial glycosidases, rat intestinal

disaccharidases and against Mycobacterium tuberculosis, the causative agent of tuberculosis. It was

found that the inhibitory proﬁle of the new products diﬀered considerably from the parent DAB and

LAB. Furthermore, some of them were active inhibiting the growth of M. tuberculosis.

Received 3rd December 2012,

Accepted 24th January 2013

DOI: 10.1039/c3ob27343a

www.rsc.org/obc

Structural modification of DAB and LAB has led to novel

derivatives with unprecedented activities and selectivities. For

1. Introduction

Polyhydroxylated pyrrolizidine 2-aminomethyl derivatives of instance, preliminary experiments suggest that 1,4-dideoxy-2-

(2R,3R,4R)-2-(hydroxymethyl)pyrrolidine-3,4-diol (also called hydroxymethyl-1,4-imino-^L-threitol (3, Fig. 1) may have a role

1,4-dideoxy-1,4-imino-^D-arabinitol, DAB) (1),¹isolated from in the mechanism of chaperoning the folding of the cystic

Arachniodes standishii and Angylocalyx boutiqueanus,²as well as fibrosis transmembrane conductance regulator (CFTR).¹⁵

from marine sponges,³and its corresponding enantiomer LAB 2-Acetamido-1,4-imino-1,2,4-trideoxy-L-arabinitol (4) and its

(2), are interesting iminocyclitols for their structural simplicity N-benzyl derivative (5) were found to be potent non-competi-

and exceptional biological activity.⁴They show a strong inhibi- tive inhibitors of ^D-hexosaminidase, that may lead to new

tory eﬀect on α-glucosidases from diﬀerent sources^5–7as well strategies for the treatment of diseases such as cancer, arterio-

as on mice and rat intestinal glycosidases.^7,8DAB is also a sclerosis and some lysosomal storage diseases, such as Tay–

potent inhibitor of glycogen phosphorylase⁹and mulberry leaf Sachs or Sandhoﬀ diseases.¹⁶Moreover, it has been reported

extracts containing DAB have also been shown to possess an that modification of the hydroxymethyl moiety to generate 3,4-

antihyperglycemic eﬀect on streptozocin (STZ)-induced dia- dihydroxypyrrolidin-2-yl (6) derivatives with diﬀerent stereo-

betic mice.¹⁰The activity regulation of glycogen-degrading chemistries at positions 2, 3 and 4 has been performed, fur-

enzymes in addition to the reduction of the postprandial gly- nishing potent inhibitors of α-mannosidases.^17–19

caemia in blood makes DAB and LAB promising therapeutic

It was found that (2R,3R,4S)- and (2S,3R,4S)-2-aminomethyl-

agents for the prevention and treatment of type-II diabetes,^11,12pyrrolidine-3,4-diol derivatives (7, 8, Fig. 1) with aromatic

and the metabolic syndrome associated to hypercaloric

diets.^12–14

^aDept Química Biológica y Modelización Molecular, Instituto de Química Avanzada

de Cataluña, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.

E-mail: pere.clapes@iqac.csic.es

^bServei de Ressonància Magnètica Nuclear, Departament de Química, Universitat

Autònoma de Barcelona, Bellaterra, Spain

^cUnitat de Tuberculosi Experimental, Fundació Institut d’Investigació en Ciències de

la Salut Germans Trias i Pujol, Universitat Autònoma de Barcelona, CIBERES, Edifici

Laboratoris de Recerca, Crtra. de Can Ruti, Camí de les Escoles, s/n, 08916,

Badalona, Spain

†Electronic supplementary information (ESI)

available. See DOI:

10.1039/c3ob27343a

Fig. 1 Structures of biologically active pyrrolidine derivatives.

This journal is © The Royal Society of Chemistry 2013

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2005

View Article Online

Paper

Organic & Biomolecular Chemistry

moieties lead to potent and selective competitive inhibitors of

α-^D-mannosidase from jack beans and from almonds.¹⁸The

parent iminocyclitol, 1,4-dideoxy-1,4-imino-^D-ribitol (9), with

the two vicinal cis-oriented hydroxyl groups mandatory for

eﬀective inhibition, already possessed inhibitory activity

against mannosidase.²⁰Furthermore, a class of polyhydroxy-

lated pyrrolidine derivatives were uncovered, namely codonop-

sinol²¹(10) and radicamines A (11) and B (12) isolated from

Codonopsis clematidea and Lobelia chinensis Lour, respecti-

vely,²²in which an aryl moiety is directly attached to the C-2

position of the pyrrolidine ring (13) (Fig. 1). These compounds

were found to be inhibitors of α-glucosidase at the micromolar

range.²³

Scheme 1 Chemo-enzymatic synthesis of DAB (1) and LAB (2) derivatives.

(a) ^D-Fructose-6-phosphate aldolase (FSA) mutant A129S/A165G, (b) H₂(50 psi)

Pd/C, (c) ^L-rhamnulose-1-phosphate aldolase from E. coli (RhuA), 200 mM

aqueous borate buﬀer, (d) Cbz-OSu, 1 : 1 dioxane–water, (e) iodoxybenzoic acid

(IBX), AcOEt reﬂux. Isolated yields in parentheses. Compounds 18 and 19 were

not isolated.

Inspired by these results we envisaged that modifications of

DAB and LAB iminocyclitols may improve their inhibitory pro-

files in terms of potency and/or selectivity. Following our

ongoing research program to develop new chemo-enzymatic

methods for the synthesis of iminocyclitols as potential inhibi-

tors of digestive glycosidases that decrease the post-prandial

glycaemia,^7,14,24we explored new derivatives with potential

application in this field. Hence, it was regarded as interesting

and significant to investigate on the synthesis and preliminary

inhibitory properties of new 2-aminomethyl derivatives of DAB

and LAB. Towards this end, a chemo-enzymatic strategy was

envisaged to modify the hydroxymethyl functionality on DAB

and LAB iminocyclitols with diﬀerent aminomethyl moieties

from aromatic amines, aminoalcohols or amino acid deriva-

tives. Moreover, piperazines and their keto analogues, such as

2-oxopiperazines, have been recognized amongst the most

important scaﬀolds in medicinal chemistry and drug discovery

industries.^25–27This prompted us to study the conjugation of

these two moieties to obtain iminocyclitol fused 2-oxopiper-

azine derivatives, namely hexahydropyrrolo[1,2-a]pyrazin-4

(1H)-one derivatives.

isolated yields, respectively, which compare favorably with

other reported procedures (e.g., between 18–30% for the under-

ivatized DAB and LAB).^5,31

At this point we pursued a more eﬃcient route that avoids

removing and reintroducing the Cbz group. Therefore, we

sought a potential new method to convert directly the aldol

adduct into N-Cbz-protected DAB or LAB derivatives. In pre-

vious works we have observed that the products formed from

the aldol addition of DHAP, DHA or glycolaldehyde to N-Cbz-

aminoaldehydes consist of a mixture of acyclic and cyclic

hemiaminal compounds in equilibrium (Scheme 2,

20–20a).^32,33The percentage of the hemiaminal was particu-

larly significant for the five membered ring, owing to the

minimal transition state strain energy for its formation as

compared with other ring sizes.³⁴Thus, we intended to

perform a reductive dehydroxylation of the cyclic hemiaminal

using the silane procedure in the presence of BF₃·OEt₂

(Scheme 2).³⁵The aldol adduct from the FSA catalyst was taken

as an example. Interestingly, the reaction proceeded in 68%

isolated yield; however, as ascertained by high field NMR data

of the resulting iminocyclitol, the major configuration at C2

was opposite to that obtained with Pd/C with a 4 : 1 2S : 2R dia-

stereomeric ratio. Hence, (2S,3R,4R)-2-(hydroxymethyl)pyrroli-

dine-3,4-diol (22) was obtained instead of 1.

Preliminary exploration of the inhibitory properties of these

compounds was directed towards commercial glycosidases

and rat intestinal glycosidases. Moreover, the iminocyclitol

derivatives active against α-^L-rhamnosidase from Penicillium

decumbens were assayed as inhibitors of the growth of the

H37Rv Pasteur Mycobacterium tuberculosis strain, the causative

agent of tuberculosis.²⁸

Remarkably, this result encompasses more general applica-

bility in the chemo-enzymatic strategy for the synthesis of

iminocyclitols, providing a useful potential stereocomplemen-

tary method for the reductive amination.

Following the synthetic plan, the hydroxymethyl group of

16 and 17 was selectively oxidized with iodoxybenzoic acid

(IBX) to furnish aldehydes 18 and 19, respectively (Scheme 1).

With the aim to develop a straightforward methodology, these

2. Results and discussion

2.1 Synthesis

We envisaged that aldehydes 18 and 19 could be the most

straightforward key intermediates to generate a collection of

(2R,3R,4R)- and (2S,3S,4S)-3,4-dihydroxypyrrolidin-2-yl deriva-

tives (Scheme 1). We have recently developed a straightforward

chemo-enzymatic asymmetric stereodivergent methodology for

the expedient synthesis of 1 and 2 starting from simple and

achiral materials such as dihydroxyacetone (14) and N-Cbz-

glycinal (15) (Scheme 1).^29,30In this work, we optimized the

conditions to obtain, after the imino protection with the Cbz,

Scheme 2 Chemo-enzymatic synthesis of (2S,3R,4R)-2-(hydroxymethyl)pyrroli-

dine-3,4-diol: (a) D-fructose-6-phosphate aldolase from E. coli mutant

A129S/A165G, (b) BF₃·OEt₂, and Et₃SiH in CH₂Cl₂−78 °C to 0 °C, (c) H₂(50 psi)

the highly valuable 16 and 17 intermediates in 46% and 53% Pd/C. Isolated yield in parentheses.

2006 | Org. Biomol. Chem., 2013, 11, 2005–2021

This journal is © The Royal Society of Chemistry 2013

View Article Online

Organic & Biomolecular Chemistry

Paper

Scheme 4 Synthesis of benzimidazole derivatives 23d and 24d. (a) AcOH at

25 °C, spontaneous oxidation; (b) H₂(22 psi), Pd/C. Isolated yields in

parentheses.

acid and O₂, gave the corresponding benzimidazole derivatives

23d and 24d in 52% and 41% isolated yields, respectively

(Scheme 4).³⁶

DAB aminoalcohol conjugates. In a similar line of thinking,

DAB aminoalcohol conjugates were also considered. They can

be regarded as analogues of 1,4-dideoxy-1,4-iminoalditols in

which the corresponding polyhydroxyl chain is substituted by

an aminoalcohol through a C–N bond.³⁷Moreover, the intro-

duction of diﬀerent functionalities might increase the recog-

nition sites of the molecule, improving its activity and

selectivity.

Following the devised strategy, aminoalcohols e–k provided

the corresponding DAB conjugates (25e–k, Scheme 5) in

39–66% isolated yields. Secondary alcohols, e.g. ^D-fagomine (l),

also reacted with the aldehyde aﬀording the corresponding

iminocyclitol conjugate (25l) in 41% isolated yield. It can be

anticipated that an identical methodology can be followed to

obtain the corresponding LAB conjugates.

The NMR analysis showed that for some conjugates a sec-

ondary product corresponding to the (2S,3R,4R)-2-(hydroxy-

methyl)pyrrolidine-3,4-diol 2-aminoalcohol derivative (see

ESI†) was identified. This resulted from epimer formation at

C2 that probably occurred during imine generation. The

amount varied depending on the aminoalcohol employed, e.g.

25 : 75 2S : 2R 25e, 1 : 9 2S : 2R 25f, 17 : 83 2S : 2R 25g and 25h,

though it was not observed for conjugates 25i–l. Separation of

epimer pairs was accomplished by cation exchange chromato-

graphy under conditions established in previous work (as an

example see NMR spectra of purified compound 25g in

ESI†).²⁴

Fig. 2 Amines used for the preparation of the 2-aminomethyl derivatives of

compounds 1 and 2.

aldehydes were readily used after evaporation of the solvent

without the need for isolation and purification. Indeed, the

aldehydes reacted with primary amines (R–NH₂, Fig. 2) in

anhydrous methanol at 20 °C under acidic conditions (acetic

acid, pH = 5.0), furnishing the corresponding imines that were

reduced in situ with NaBH₃CN. Deprotection of the Cbz group

by hydrogenolysis in the presence of Pd/C gave the correspond-

ing 2-aminomethyl derivatives of compounds 1 and 2 (see the

next sections).

DAB and LAB derivatives with aromatic amines. The strategy

depicted above worked for the selected aromatic amines a, b

and c, which furnished derivatives 23a–c and 24a–c (Scheme 3)

in 38–44% and 34–54% isolated yields, respectively.

Furthermore, unexpectedly (2R,3R,4R)- and (2S,3S,4S)-2-

(aminomethyl)-1-(quinolin-3-yl)pyrrolidine-3,4-diol (23e and

24e, respectively) were isolated (5%) after treatment of N-Cbz

derivatives of 23c and 24c with H₂in the presence of Pd/C.

These products were characterized and are described in the

Experimental section and ESI.†

Amino acid conjugates: preparation of iminocyclitol fused

2-oxopiperazine derivatives. By analogy to the general

methodology described above, we envisaged that the aldehydes

Expectedly, the reaction of the aldehydes 18 and 19 with

N-methyl-1,2-phenylenediamine (d), in the presence of acetic

Scheme 3 Synthesis and isolated yields of 2-aminomethyl aromatic derivatives

23 and 24: (a) amines a–c, NaBH₃CN, AcOH, (b) H₂(22 psi) Pd/C. Structures of

compounds 23e and 24e.

Scheme 5 Synthesis and isolated yields of DAB aminoalcohol conjugates. (a)

Aminoalcohol e–l, NaBH₃CN, AcOH; (b) H₂(22 psi), Pd/C.

This journal is © The Royal Society of Chemistry 2013

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2007

View Article Online

Paper

Organic & Biomolecular Chemistry

Scheme 6 Synthetic strategy towards iminocyclitol fused 2-oxopiperazine

derivatives.

18 and 19 can react with 1 equiv. of an amino acid to furnish

the 2-aminomethyl DAB or LAB derivatives 26 and 27, respect-

ively. Then, using ideas stemming from peptide chemistry,

intramolecular lactamization can be forced, after Cbz removal

from 26 and 27, by analogy with the undesired diketopipera-

zine formation that occurs during solid phase peptide syn-

thesis (Scheme 6).^26,38

Scheme 8 Synthesis and isolated yields of iminocyclitol fused 2-oxopiperazine

28 and 29 and amino acid conjugate derivatives 30o, t. (a) H₂(22 psi), Pd/C; (b)

cyclization at rt, 40 °C or 100 °C (see text).

Given the approach adumbrated above, the reaction

between aldehydes 18 or 19 and 1 equiv. of the selected amino

acid derivatives (Scheme 7) furnished the corresponding DAB

(26m–r, t–v) or LAB (27m–q, s–u) conjugates. Amino acid

amides (i.e., amide derivatives from amino acids) gave good

isolated yields (51–70%) and were the derivatives of choice.

Amino acid esters (i.e., ester derivatives from amino acids)

were the most obvious selection but it was discouraging to

find out that only phenylalanine methyl ester (r) was readily

able to form the corresponding 26r derivative. Furthermore,

the β-carboxylate of the aspartic acid amide (s) must be pro-

tected (t) to make the reaction proceed towards the product 26t

(or 27t).

The next step entailed the deprotection of the Cbz group

and the lactamization (i.e. intramolecular aminolysis) to

furnish the corresponding iminocyclitol fused 2-oxopiperazine

moiety (Scheme 8). Thus, the glycinamide conjugate 26m gave

complete lactamization readily after the removal of the Cbz

group at room temperature. The alaninamide and prolinamide

conjugates 26n and 26v, respectively, needed 40 °C overnight

to aﬀord the complete reaction, whereas the rest required over-

night heating at 100 °C. Attempted lactamization of the valin-

amide derivative 26o failed under various reaction conditions,

probably due to steric eﬀects of the isopropyl group. The con-

jugate 26t did not form the cyclic species under mild con-

ditions, while a number of unidentified by-products appeared

when it was heated at 100 °C. Removal of the β(O^tBu) group

(26s) did not help the lactamization reaction, decomposing

under the reflux conditions in water. The phenylalanine amide

derivative 26q furnished only 50% of the bicyclic product,

whereas quantitative yields were obtained from the corre-

sponding methyl ester derivative 26r.

For the LAB derivatives, the cyclization was faster and Gly–

NH₂(m), Ala–NH₂(n) and Leu–NH₂(p) reacted at room temp-

erature, readily after the removal of the Cbz protecting group.

Derivatives from Phe–NH₂(q), Asp–NH₂(s) and Arg–NH₂(u)

partially cyclize at room temperature and the reaction was

completed at 40 °C. The aspartic acid derivative, 27s, gave the

corresponding intramolecular product in quantitative yields

whereas the corresponding O^tBu protected analogue (27t) did

not react. Moreover, the Phe–NH₂conjugate 27q gave the

corresponding 2-oxopiperazine–iminocyclitol derivative at

40 °C. Val (o) was the only derivative that did not perform the

lactamization reaction.

These resulted in a new class of hexahydropyrrolo[1,2-a]-

pyrazin-4(1H)-one derivatives (i.e. 2-oxopiperazine derivatives)

that might be considered indolizidine analogues (Scheme 8).

2.2 Inhibitory activity

Commercial glycosidases. The DAB and LAB derivatives

23a–d, 24a–d, 25e–l, 28, 29 and 30 were screened as inhibitors

against a panel of commercial glycosidases (Table 1) and rat

intestinal disaccharidases, i.e. sucrase, lactase, threalase and

maltase (Table 2). The inhibitory activity was compared with

that of the parent compounds 1 and 2, measured in our lab-

oratory in previous work.⁷The inhibitory profiles of the new

Scheme 7 Synthesis and isolated yields of N-Cbz-DAB and -LAB amino acid

amide and ester conjugates: (a) amino acids m–v, NaBH₃CN.

2008 | Org. Biomol. Chem., 2013, 11, 2005–2021

This journal is © The Royal Society of Chemistry 2013

View Article Online

Organic & Biomolecular Chemistry

Paper

Table 1 Activities, IC₅₀(μM) and K_i(μM) (in parentheses), of the compounds synthesized against commercial glycosidases^a

α-^D-Glucosidase α-D-Glucosidase

β-D-Glucosidase β-D-Galactosidase α-L-Rhamnosidase α-D-Mannosidase α-L-Fucosidase

Product baker’s yeast

rice

sweet almonds

bovine liver

P. decumbens

jack beans

bovine kidney

23a

24a

23b

24b

23c

24c

24d

25e

25f

n.i.

370 11

(215 18)

C

155 19

(406 128)

NC, α = 1

n.i.

40

6

620 29

(236 61)

C

n.i.

15.6 0.5

(38 12)

NC, α = 1

n.i.

(44 13)

NC, α = 1

n.i.

832 105

(338 116)

C

n.i.

136 13

(208 102)

NC, α = 1

165 44

(170 95)

C

247 26

(100 66)

NC, α = 1

n.i.

38

4

274 35

(699 112)

NC, α > 1

n.i.

(41 13)

C

n.i.

263 50

(308 55)

NC, αα = 1

n.i.

132 31

(132 27)

C

320 130

(331 19)

NC, α = 1

n.i.

273 31

(358 52)

NC α > 1

158 25

(153 8)

NC α > 1

n.i.

25h

25i

260 100

(734 19)

NC α > 1

150 71

(223 9)

NC α > 1

460 353

(561 30)

NC α > 1

n.i.

4.6 1.6

(2.1 0.8)

C

110 13

(96 10)

NC α > 1

n.i.

342 90

(144 90)

C

n.i.

25j

n.i.

25l

466 64

(186 21)

C

76 19

(39 2)

NC α = 1

208 23

(261 29)

C

n.i.

28n

28p

28u

29m

29n

29p

29q

29s

29u

n.i.

1116 28

n.i.

9.2 1.5

(7.1 1.5)

C

285 15

(394 19)

C

n.i.

60 19

(21 7)

C

n.i.

401 35

(323 65)

NC α > 1

n.i.

239

9

n.i.

(323 64)

NC α > 1

340 25

(337 84)

NC α > 1

50 14

(76 8)

UC

14

(13 2)

C

148 50

(87 25)

C

382 41

(176 4)

C

2

n.i.

691 86

n.i.

174 12

(103 27)

NC α = 1

n.i.

41

8

(181 24)

UC

140 44

(124 13)

NC α = 1

n.i.

709 56

This journal is © The Royal Society of Chemistry 2013

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2009

View Article Online

Paper

Organic & Biomolecular Chemistry

Table 1 (Contd.)

α-^D-Glucosidase α-D-Glucosidase

β-D-Glucosidase β-D-Galactosidase α-L-Rhamnosidase α-D-Mannosidase α-L-Fucosidase

Product baker’s yeast

rice

sweet almonds

bovine liver

P. decumbens

jack beans

bovine kidney

30o

30t

1

1.1 0.1

(54 20)

NC α > 1

3.9 3.1

(16.7 7.8)

C

0.33 0.02

(0.17 0.01)

C

448 214

(190 33)

C

685 110

(451 170)

C

n.i.

218

3

276 25

(100 64)

C

685 112

(1014 81)

NC, α > 1

286 27

(111 60)

NC, α > 1

n.i.

20

(5 1)

C

1

(104 75)

C

0.05 0.01

(0.040 0.003)

NC, α > 1

2

1.8 0.1

(0.8 0.1)

NC, α = 1

56

(98 5)

NC, α = 1

5

n.i.

^aData are means of triplicate experiments standard error of the mean (SE). C: competitive inhibition. NC: noncompetitive inhibition. UC:

uncompetitive inhibition.⁴⁶n.i.: no inhibition, i.e. IC₅₀≥ 1 mM.

Table 2 Activities, IC₅₀(μM), of the compounds synthesized against rat intesti-

considerably, all of them have a DAB configuration (see

Schemes 6 and 8). The aromatic derivatives and aminoalcohol

nal saccharidases^a

conjugates were mostly inactive against α-^D-glucosidase from

rice. Among the fused 2-oxopiperazine iminocyclitol deriva-

tives, compound 29p was the best inhibitor, while 28n and 28u

showed inhibitory properties comparable to the parent com-

pound DAB.

β-^D-Glucosidase from sweet almonds: Compound 24b was a

moderate inhibitor of β-^D-glucosidase from sweet almonds

while the parent compound LAB and its enantiomer DAB were

weak inhibitors of this glycosidase. The rest of the evaluated

compounds had either weak activities or were completely inac-

tive against this glycosidase.

β-^D-Galactosidase from bovine liver: Aromatic derivatives

23a, 23c and 24c were weak inhibitors while the parent DAB

and LAB were inactive towards this glycosidase. It appears that

the presence of an aromatic moiety is necessary for the inhibi-

tory activity.^39,40Indeed, among the 2-oxopiperazine imino-

cyclitol fused derivatives only 29q, derived from phenyalanine,

showed some activity. The rest of the derivatives were not

inhibitors of this glucosidase.

Sucrase

Lactase

Maltase

(3.91 0.05 UI)^b

(n = 2)

(0.85 0.07 UI)^b

(n = 2)

(26.89 1.50 UI)^b

(n = 2)

Product

23a

24a

23c

24c

24d

25i

28n

28p

28u

29p

29q

29s

1

318 101

538 356

739 392

321 59

173 72

99 52

57 29

320 57

77 17

n.i.

140 84

50 36

n.i.

77 34

119 11

304 23

151

56

2

19 11

174 84

342 123

22 12

263 99

n.i.

50 36

0.2 0.1

2

0.29 0.02

^aThe experiments were performed in triplicate for each set of

saccharidases. Two sets of saccharidases from two diﬀerent rats (n = 2)

were used. IC₅₀s are expressed as μM standard error of the mean (SE).

^b1 UI corresponds to 1 μmol of glucose formation per hour at 37 °C in

phosphate buﬀer, pH 6.8. UI (μmol substrate h⁻¹mg⁻¹protein); n.i. no

inhibition, IC₅₀≥ 1 mM.

α-^L-Rhamnosidase from Penicillium decumbens: Among the

aromatic substitutions only those with LAB configuration,

24a–d, were moderately to weakly active against α-^L-rhamno-

derivatives diﬀer considerably from those of 1 and 2 (Table 1). sidase; consequently, the orientation of the hydroxyl groups

Compounds 23d, 25g, 25k, 28m, 28q and 28v (not included in and the amine moiety is a strong factor that determines the

Table 1) were not inhibitors (i.e. IC₅₀≥ 1 mM) of any assayed right interaction with the glycosidase. It has been suggested

glycosidase.

that the α-^L-rhamnosidase inhibition shown by some pyrroli-

α-^D-Glucosidase from baker’s yeast and rice: The aromatic dines can be rationalized in terms of stereochemical simi-

conjugates 23a–c and 24a–d have much lower inhibitory prop- larities with α-^L-rhamnose.^40,41Thus, it is apparent that the

erties against α-^D-glucosidase from baker’s yeast than the stereochemistry of 24a–d (2S,3S,4S) matches that of the rham-

parent compounds DAB and LAB (Table 1). Only compound nose moiety at C-3, C-4 and C-5. This would place the 2-aryl

24a showed moderate non-competitive inhibition against this containing substituent at the same location as the 5-methyl

glucosidase. Among the rest of the derivatives, compounds group of rhamnose. The best inhibitor was compound 24a

25i, 28p, and 30t were the best competitive inhibitors of α-^D- whose structure is similar to those reported by Chapman et al.

glucosidase from baker’s yeast with comparable activities. (e.g. (2S,3S,4S)-2-benzylpyrrolidine-3,4-diol).⁴⁰Moreover, Kim

Compound 30o was the best non-competitive inhibitor of this et al. also proposed a role as aglycone for hydrophobic substi-

glucosidase. Although the structure of the substituent diﬀers tuents at the C-2 position of pyrrolidines.⁴¹This is consistent

2010 | Org. Biomol. Chem., 2013, 11, 2005–2021

This journal is © The Royal Society of Chemistry 2013

View Article Online

Organic & Biomolecular Chemistry

Paper

Table 3 Minimum inhibitory concentrations (mg mL⁻¹) against the H37Rv

Pasteur M. tuberculosis strain

with the absence of inhibitory properties of the aminoalcohol

and 2-oxopiperazine derivatives, where basically non-aromatic

moieties are present.

Product

MIC (mg mL⁻¹

)

Product

MIC (mg mL⁻¹

)

α-^D-Mannosidase from jack beans and α-L-fucosidase from

bovine kidney: It appears that a cis arrangement of the

hydroxyl groups at C-3 and C-4, which parallels that of the

hydroxyl groups at C-2 and C-3 of α-^D-mannose and other

known pyrrolidine inhibitors like mannostatin A, is a strong

structural requirement for the inhibition of α-^D-mannosidase

by pyrrolidine iminocyclitols.^19,42,43The fact that the com-

pounds synthesized do not match this C-3 and C-4 configur-

ation is probably the reason for their inability to inhibit this

glycosidase.

Similarly to α-^D-mannosidase, α-L-fucosidase has also a

strong stereochemical demanding active site.⁴³Pyrrolidine

derivatives with stereoconfiguration (3S,4R,5S) were reported

as strong inhibitors of α-^L-fucosidase,^43,44whereas diastereo-

meric analogues were usually moderate to weak inhibitors.⁴⁵

The derivatives obtained in the present work have (3R,4R) or

(3S,4S) configuration, therefore they showed no inhibition

activities.

Intestinal disaccharide glycosidases. Concerning their

inhibitory properties against intestinal disaccharide glyco-

sidases, 23a, 23c, 24a, 24c and 24d were weak inhibitors of

sucrase while the parent compounds DAB and LAB were mod-

erate to strong inhibitors of this glycosidase (Table 2). More-

over, the LAB derivatives 24a–d lost the strong inhibitory

activity against maltase. Among the aminoalcohol derivatives

only compound 25i showed inhibitory activity against sucrase

and maltase. Concerning the iminocyclitol fused 2-oxopiper-

azine derivatives, it is remarkable the activity of 29p against

sucrase and maltase, which is comparable to the DAB com-

pound, but with no inhibitory activity against lactase. This com-

pound was also the best against α-^D-glucosidase from rice. The

rest of the compounds showed moderate to weak activity on

both sucrase and maltase. Interestingly, no inhibitory activity

was observed against lactase for the compounds under study.

Inhibitory activity against Mycobacterium tuberculosis

H37Rv laboratory strain. It has been suggested that the imino-

cyclitol derivatives which are inhibitors of α-^L-rhamnosidase

from P. decumbens could have the ability to inhibit dTDP-^L-

rhamnose biosynthesis on M. tuberculosis, and therefore con-

stitute potential chemotherapeutic agents for tuberculosis.²⁸

The inhibitors of α-L-rhamnosidase found in this work

were assayed in mycobacterial systems and the Minimum

Inhibitory Concentration values (MIC; i.e. the lowest drug con-

centration that prevented the development of colour akin to

the bacteria growth) were determined (Table 3). The lowest

MIC values were obtained for compounds 23d, 24b and 24d,

23a

23b

23c

23d

1

2.5

1.3

0.63

2.5

24a

24b

24c

24d

2

2.5

0.31

2.5

0.63

2.5

3. Conclusions

An eﬃcient chemo-enzymatic strategy for the synthesis of

2-aminomethyl derivatives of DAB (1) and LAB (2) was devel-

oped. The straightforward chemo-enzymatic access to imino-

cyclitols 1 and 2, the use of mild and selective oxidation

conditions with IBX, followed by a reductive amination step,

provides easy access to a number of new derivatives with aro-

matic amines, aminoalcohols or amino acids, the latter

leading to the formation of piperazine–iminocyclitol fused

compounds. An alternative method to generate the Cbz-imino-

sugar derivatives was tested that led to (2S,3R,4R)-2-(hydroxy-

methyl)pyrrolidine-3,4-diol. This may open new possibilities

for obtaining novel stereocomplementary derivative epimers at

C-2 to those from 1 and 2.

The inhibitory properties of the new 1 and 2 derivatives

against the panel of commercial glycosidases and rat intestinal

disaccharidases diﬀered considerably from those of the parent

compounds DAB and LAB. The aromatic aminomethyl deriva-

tives 23 and 24 are moderate to good inhibitors of α-^L-rhamno-

sidase. Particularly 24a has better inhibitory properties than

its parent LAB. Aromatic derivatives 23a–d and 24a–d were

found to be moderate inhibitors of the growth of M. tuberculo-

sis H37Rv laboratory strain, the causative agent of tuberculosis.

However, the inhibitory pattern could not be correlated with

the activity observed against α-^L-rhamnosidase. The amino-

alcohol, amino acid and oxopiperazine derivatives are selective

inhibitors of α-^D-glucosidases, particularly 25i and 30t were

selective towards α-^D-glucosidase from baker’s yeast. Concern-

ing the intestinal disaccharide glycosidases it is remarkable

that the derivatives are selective for sucrase and maltase and

completely devoid of activity against rat intestinal lactase. Par-

ticularly 29p has inhibitory activity against sucrase and

maltase comparable to DAB, but it does not inhibit lactase.

Experimental

whereas no significant diﬀerences relative to 1 and 2 were (2R,3R,4R)-N-Benzyloxycarbonyl-2-(hydroxymethyl)pyrrolidine-

observed for the other compounds. This might indicate that 3,4-diol (16). FSA A165G (150 U, 150 mg, 1.06 U mg⁻¹) and

the products are not acting on the target rhamnosidase proces- dihydroxyacetone DHA (1.3 g, 14.5 mmol) were dissolved in

sing enzymes of the cell wall. The standard compound iso- 0.1 M triethanolamine buﬀer, pH 7.0 (135 mL). This solution

niazid (MIC: 0.25 μg mL⁻¹) was evaluated as a positive control was added to N-Cbz-glycinal (2.25 g, 11.6 mmol) dissolved in

in this assay and it was consistent with the reported values for N,N-dimethylformamide (DMF, 15 mL) and the mixture was

this product.⁴⁷

shaken at 25 °C. After 24 h (99% conversion) the crude was

This journal is © The Royal Society of Chemistry 2013

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2011

View Article Online

Paper

Organic & Biomolecular Chemistry

diluted with H₂O up to a volume of 150 mL and loaded onto a The aqueous residue was diluted with EtOH (400 mL). The

glass column (5 cm diameter × 20 cm length, volume 400 mL) solution was divided into two batches (400 mL) and each one

packed with the Amberlite™ XAD™ 16 (Rohm and Haas) was treated overnight with H₂(50 psi) in the presence of Pd/C

stationary phase, which was previously equilibrated with H₂O. (0.6 g, 10% Pd). The catalyst was removed by filtration and

After loading, the column was washed with H₂O (800 mL, 2 EtOH–water was evaporated in vacuum. NMR data and phys-

column volumes). This step removed eﬃciently the enzyme, ical properties matched those already published using the

the excess of DHA and the salts. The aldol adduct was then same methodology.³⁰The aqueous solution (ca. 150 mL) was

eluted with 2 : 3 H₂O–EtOH (800 mL, 2 column volumes). The diluted with 1,4-dioxane (150 mL) and solid NaHCO₃(1.8 g,

fractions containing the product were pooled and the solvent 21.6 mmol) was added under stirring. After cooling to 0 °C,

reduced to about 300 mL in vacuum. The aqueous residue was benzyl chloroformate (1.7 mL, 11.8 mmol) was added drop-

diluted with EtOH (200 mL). The solution was divided into two wise. After the addition, the reaction mixture was allowed to

batches (250 mL) and each one was treated overnight with H₂warm up to room temperature and it was stirred overnight.

(50 psi) in the presence of Pd/C (0.4 g, 10% Pd). The catalyst Dioxane was removed under vacuum, the aqueous residue was

was removed by filtration and EtOH–water was evaporated in diluted with saturated NaHCO₃solution (100 mL) and the

vacuum. NMR data and physical properties matched those product extracted with ethyl acetate (4 × 150 mL). The organic

already published using the same methodology.^29,33The layer was dried over Na₂SO₄, and concentrated in vacuum. The

aqueous solution (200 mL) was diluted with 1,4-dioxane crude material was purified by flash column chromatography

(200 mL) and solid NaHCO₃(1.9 g, 23.2 mmol) was added on silica (from 100 : 0 to 9 : 1 EtOAc–MeOH) to yield the title

under stirring. After cooling to 0 °C, benzyl chloroformate compound (1.73 g, 53% yield, 98% purity by HPLC). [α]_D²²

=

(1.8 mL, 12.7 mmol) was added dropwise. After the addition, +25.0 (c 1.2 in MeOH). HPLC retention time and NMR data

the reaction mixture was allowed to warm up to room temp- were identical to those of DAB.

erature and it was stirred overnight. Dioxane was removed

(2S,3R,4R)-2-(Hydroxymethyl)pyrrolidine-3,4-diol

(also

under vacuum, the aqueous residue was diluted with saturated called 1,4-dideoxy-1,4-imino-^L-xylitol) (22). The aldol adduct

NaHCO₃solution (100 mL) and the product extracted with (500 mg, 1.77 mmol) obtained from the aldol addition of DHA

ethyl acetate (4 × 150 mL). The organic layer was dried over to N-Cbz-glycinal catalysed by ^D-fructose-6-phosphate aldolase

Na₂SO₄, and concentrated in vacuum. The crude material was mutant A165G (see above) was dissolved in anhydrous CH₂Cl₂

purified by flash column chromatography on silica (from (12 mL) and cooled down to 0 °C. A solution of BF₃·Et₂O

100 : 0 to 9 : 1 EtOAc–MeOH) to yield the title compound (1.4 g, (0.22 mL, 1.77 mmol, 1 equiv.) and subsequently Et₃SiH

46% yield). HPLC analysis: gradient elution from 10% to 70% (0.57 mL, 3.54 mmol, 2 equiv.) were added under N₂and the

B in 40 min; t_R= 14.5 min, 98% purity by HPLC. [α]²_D²= −28.0 reaction mixture was left to reach room temperature under stir-

(c 1.0 in MeOH) (lit.,⁴⁸[α]_D²²= −28.9 (c 1.9 in MeOH); lit.,⁵[α]²_D²ring. After 2 h the reaction was quenched to pH = 7 with satu-

1

= −29.7 (c 0.3 in MeOH)). H NMR (400 MHz, CD₃OD) δ 7.32 rated NaHCO₃(5 mL). The aqueous layer was diluted with

(m, 5H, arom), 5.13 (m, 2H, OCH₂Ph), 4.17 (s, 1H, H-3), 4.12 brine (5 mL), and the mixture extracted with EtOAc, dried over

(s, 1H H-3-rotamer), 4.04 (br s, 1H, H-4), 3.82 (m, 4H, H-2-H-5- anhydrous Na₂SO₄and concentrated under reduced pressure.

H-6-H-6′), 3.38 (m, 1H, H-5′) (complex spectrum due to the The residue was purified by flash column chromatography

existence of rotamers as described also by Fleet and Smith⁵). (30 : 1 EtOAc–CH₃OH) to give the corresponding Cbz protected

¹³C NMR (101 MHz, CD₃OD) δ 157.3 (CvO), 157.1 (CvO derivative 21 as an oil (320 mg, 68% yield). [α]²_D²= +20.0 (c 1.0

1

rotamer), 138.0 (C-Ar), 137.9 (C-Ar rotamer), 129.5 (C-Ar), 129.1 in MeOH). Purity 98% by HPLC. H NMR (400 MHz, CD₃OD)

(C-Ar), 129.1 (C-Ar), 128.9 (C-Ar), 128.8 (C-Ar), 79.4 (C-3), 78.7 δ = 7.33 (m, 5H, arom), 5.14 (m, 2H, OCH₂Ph), 4.14 (m, 2H,

(C-3 rotamer), 76.2 (C-4), 75.6 (C-4 rotamer), 68.6 (C-2), 68.3 H-3-H-4), 3.89 (m, 3H, H-2-H-6-H-6′), 3.65 (m, 1H, H-5), 3.40

(C-2 rotamer), 68.1 (CH₂Ph), 68.0 (CH₂Ph rotamer), 61.8 (C-6), (m, 1H, H-5′). ¹³C NMR (101 MHz, CD₃OD) δ = 157.76 (CvO),

61.6 (C-6 rotamer), 54.8 (C-5), 54.4 (C-5 rotamer).

157.35 (CvO rotamer), 138.04 (C-Ar), 137.94 (C-Ar rotamer),

(2S,3S,4S)-N-Benzyloxycarbonyl-2-(hydroxymethyl)pyrroli- 129.51 (C-Ar), 129.06 (2C-Ar), 128.86 (2C-Ar), 77.96 (C-3), 77.53

dine-3,4-diol (17). RhuA (400 U, 32 mL of NH₄SO₄suspension, (C-3 rotamer), 75.21 (C-4), 74.86 (C-4 rotamer), 68.28 (CH₂Ph),

0.35 mg protein mL⁻¹, 12.5 U mL⁻¹) and dihydroxyacetone 68.15 (CH₂Ph rotamer), 62.81 (C-2), 61.66 (C-2 rotamer), 60.85

(DHA) (1.35 g, 15 mmol) were dissolved in sodium borate (C-6), 60.27 (C-6 rotamer), 53.26 (C-5), 53.10 (C-5 rotamer). The

0.25 M, pH 7.0 (160 mL). This solution was added to N-Cbz- presence of rotamers makes it diﬃcult to obtain the relative

glycinal (2.33 g, 12 mmol) dissolved in DMF (40 mL) and the stereochemistry. Moreover, some important signals were over-

mixture was shaken at 25 °C. After 24 h (90% conversion) the lapped making it diﬃcult to analyse the nOe experiments.

crude was diluted with H₂O up to a volume of 200 mL and Therefore it was decided to remove the Cbz group by treatment

loaded onto a glass column packed with Amberlite™ XAD™ of

a sample of the N-Cbz-1,4-dideoxy-1,4-imino-^L-xylitol

16 (Rohm and Haas) following an identical procedure to the (40 mg, 0.14 mmol) with H₂(22 psi) in the presence of Pd/C

one described above with minor modifications. The aldol (20 mg). After removal of the Pd/C by filtration and lyophilisa-

adduct was then eluted with 2 : 3 H₂O–EtOH (1000 mL, 2.5 tion, the title compound 22 (20 mg, 0.14 mmol) was obtained

column volumes). The fractions containing the product were in quantitative yield. NMR and physical data matched those

pooled and the solvent reduced to about 400 mL in vacuum. reported using other procedures.^49,50[α]_D²²= −3.0 (c 1.0 in H₂O)

2012 | Org. Biomol. Chem., 2013, 11, 2005–2021

This journal is © The Royal Society of Chemistry 2013

View Article Online

Organic & Biomolecular Chemistry

Paper

(lit.,⁴⁹[α]²_D²= −4.0 (c 0.10 in H₂O); lit.,⁵⁰[α]²_D²= −4.4 (c 0.04 in Formation of iminocyclitol fused 2-oxopiperazine derivatives

CH₃OH)). ¹H NMR (400 MHz, D₂O) δ = 4.25 (dt, J = 4.9, 1.9 Hz,

1H, H-4), 4.20 (dd, J = 4.0, 1.7 Hz, 1H, H-3), 3.88 (dd, J = 11.5,

After the Cbz-group removal the product was left at room

temperature without solvent or dissolved in water and heated

at 40 or 100 °C depending on the derivative until the intra-

molecular aminolysis was completed (see text). Then the

product was assayed without any further purification.

DAB and LAB aromatic 2-aminomethyl derivatives 23 (phys-

6.0 Hz, 1H, H-6), 3.76 (dd, J = 11.5, 7.3 Hz, 1H, H-6′), 3.51

(ddd, J = 7.2, 6.1, 4.1 Hz, 1H, H-2), 3.41 (dd, J = 12.7, 5.0 Hz,

1H, H-5), 2.93 (dd, J = 12.8, 2.0 Hz, 1H, H-5′). ¹³C NMR

(101 MHz, D₂O) δ = 76.14 (C-4), 75.87 (C-3), 61.46 (C-2), 59.05

(C-6), 50.59 (C-5). HRMS (ESI-TOF): m/z [M

+

H]⁺for

ical properties and characterization of compounds 24 can be

found in ESI†). (2R,3R,4R)-3,4-Dihydroxy-2-((phenylamino)

methyl)pyrrolidine (23a). The precursor (2R,3R,4R)-N-benzyl-

oxycarbonyl-3,4-dihydroxy-2-((phenylamino)methyl)pyrrolidine

(170 mg, 58% yield) was purified by flash chromatography on

silica (3 : 2 AcOEt–hexane). HPLC analysis: gradient elution

from 2% to 62% B in 30 min; t_R= 25.0 min. The title com-

pound (100 mg, 66% yield) was prepared according to the

general procedure described above. HPLC purification: gradi-

ent elution from 0 to 60% B in 40 min. HPLC analysis: gradi-

C₅H₁₂NO₃⁺calculated 134.0817; observed 134.0819.

Oxidation reaction. Typical example: Compound 16 (0.22 g,

0.82 mmol) was dissolved in AcOEt (50 mL) at 40 °C. To this

solution, 2-iodoxybenzoic acid (IBX) (0.92 g, 3.3 mmol) was

added and the reaction mixture was stirred under reflux. After

3.5 h the reaction mixture was cooled down to room temp-

erature, the solid removed by filtration and the solvent evapor-

ated under reduced pressure. This product was used in the

next step without further purification and it was not charac-

terized. Reductive amination reactions. Typical example: The

crude from the oxidation reaction was dissolved in dry MeOH

(50 mL) to have an aldehyde concentration of 0.016 M

(0.8 mmol). To this solution, benzylamine (0.45 mL,

4.1 mmol) in glacial acetic acid (0.23 mL, 4.1 mmol) was

added and stirred for 2 h at room temperature. Then,

NaBH₃CN (0.08 g, 1.23 mmol) was added and the reaction

mixture was stirred overnight. The solvent was removed under

reduced pressure, and the crude product was purified either by

flash chromatography on silica or preparative HPLC. Purifi-

cation by HPLC was performed as follows (general procedure).

The crude was dissolved in MeOH and loaded onto a semi-pre-

parative X-Terra Prep MS C-18, 10 μm, 19 × 250 mm column.

The solvent system used was: solvent (A): aqueous trifluoroace-

tic acid (TFA) (0.1% (v/v)) and solvent (B): TFA (0.095% (v/v)) in

4 : 1 ACN–H₂O or plain MeOH. Salts and solvents were washed

out with 100% A during 10 min. The product was eluted with a

gradient of B (see below in each case). The flow rate was 10 mL

min⁻¹and the products were detected at 215 nm. The fractions

were analysed by HPLC. Fractions containing the product were

pooled and lyophilized.

ent elution from 2% to 62% B in 40 min; t_R= 13.3 min. [α]_D²²

=

+46.4 (c 1.4 in MeOH). ¹H NMR (500 MHz, CD₃OD) δ = 7.15

(dd, J = 8.5, 7.4 Hz, 2H), 6.92–6.52 (m, 3H), 4.27–4.18 (m, 1H),

4.11 (d, J = 0.8 Hz, 1H), 3.72 (ddd, J = 9.4, 5.4, 1.5 Hz, 1H), 3.58

(dd, J = 14.0, 5.5 Hz, 1H), 3.53 (dd, J = 14.0, 9.6 Hz, 1H), 3.48

(dd, J = 12.0, 3.7 Hz, 1H), 3.34 (d, J = 11.9 Hz, 1H). ¹³C NMR

(101 MHz, CD₃OD) δ = 148.8, 130.2, 119.0, 114.1, 78.5, 76.2,

67.2, 52.2, 45.0. HRMS (ESI-TOF): m/z [M

C₁₁H₁₇N₂O₂⁺calculated 209.1285; observed 209.1276.

+

H]⁺for

(2R,3R,4R)-2-((Benzylamino)methyl)-3,4-dihydroxypyrrolidine

(23b). The precursor (2R,3R,4R)-N-benzyloxycarbonyl-2-((benzyl-

amino)methyl)-3,4-dihydroxypyrrolidine (165 mg, 56% yield)

was purified by flash chromatography on silica (9 : 1 AcOEt–

MeOH). HPLC analysis: gradient elution from 2% to 62% B in

40 min; t_R= 10.6 min. The title compound (81 mg, 78% yield)

was prepared according to the general procedure described

above. HPLC purification: gradient elution from 0 to 60% B in

40 min. HPLC analysis: gradient elution from 2% to 62% B in

1

30 min; t_R= 25.0 min. [α]²_D²= +14.3 (c 1.0 in MeOH). H NMR

(500 MHz, CD₃OD) δ = 7.55–7.44 (m, 5H), 4.28 (s, 2H),

4.26–4.23 (m, 1H), 4.21 (s, 1H), 3.82 (t, J = 6.1 Hz, 1H), 3.58

(dd, J = 12.2, 5.0 Hz, 3H), 3.41 (d, J = 12.0 Hz, 1H). ¹³C NMR

(101 MHz, CD₃OD) δ = 132.8, 131.0, 130.6, 130.2, 79.3, 75.9,

64.9, 53.1, 53.1, 48.5. HRMS (ESI-TOF): m/z [M + H]⁺for

C₁₂H₁₉N₂O₂⁺calculated 223.1441; observed 223.1431.

The Cbz-protected derivative (165 mg, 0.46 mmol) was dis-

solved in ethanol (100 mL) and treated with H₂(22 psi) in the

presence of Pd/C (10% Pd, 80 mg) for 24 h at room temp-

erature. The catalyst was removed by filtration and the solvent

evaporated under vacuum.

Purification. For amines, the crude was purified by prepara-

(2R,3R,4R)-3,4-Dihydroxy-2-((quinolin-3-ylamino)methyl)-

tive HPLC, see conditions in each case. For aminoalcohols, pyrrolidine (23c). The precursor (2R,3R,4R)-N-benzyloxycarbonyl-

when necessary, the product was further purified by cation 3,4-dihydroxy-2-((quinolin-3-ylamino)methyl)pyrrolidine

exchange chromatography on the CM-Sepharose CL-6B (Amer- (167 mg, 55% yield) was purified by flash chromatography on

+

sham Pharmacia) stationary phase in NH₄form. The station- silica (19 : 1 AcOEt–MeOH). HPLC analysis: gradient elution

ary phase was packed into a glass column (450–25 mm) to from 2% to 62% B in 30 min; t_R= 22.6 min. The title com-

provide a final bed volume of 220 mL. The flow rate was 4 mL pound (110 mg, 70% yield) was prepared according to the

+

min⁻¹. The CM-Sepharose-NH₄was washed initially with general procedure described above. HPLC purification: gradi-

H₂O. An aqueous solution of the crude material at pH 5 was ent elution from 0 to 50% B in 40 min. HPLC analysis: gradi-

then loaded onto the column. Minor coloured impurities were ent elution from 2% to 62% B in 40 min; t_R= 11.2 min. [α]_D²²

=

washed away with H₂O (440 mL, 2 bed volumes). Products +22.6 (c 0.5 in MeOH). ¹H NMR (400 MHz, CD₃OD) δ = 8.70

were eluted with aqueous NH₄OH (0.01 M) (400 mL). Pure frac- (d, J = 2.8 Hz, 1H), 7.98 (ddd, J = 5.4, 4.9, 2.8 Hz, 3H),

tions were pooled and lyophilized.

7.74–7.68 (m, 2H), 4.31–4.27 (m, 1H), 4.20 (d, J = 1.1 Hz, 1H),

This journal is © The Royal Society of Chemistry 2013

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2013

View Article Online

Paper

Organic & Biomolecular Chemistry

3.81 (dd, J = 13.4, 3.4 Hz, 3H), 3.56 (dd, J = 12.0, 3.6 Hz, 1H), 1H), 3.37 (dd, ³J(H,H) = 12.3, 5.2 Hz, 1H), 3.24 (d, ³J(H,H) = 4.9

3.41 (d, J = 12.0 Hz, 1H). ¹³C NMR (101 MHz, CD₃OD) δ = Hz, 1H), 3.15 (dd, ³J(H,H) = 13.2, 9.1 Hz, 1H), 3.06 (m, 3H). ¹³

C

143.77, 138.36, 135.37, 131.65, 130.61, 130.10, 128.14, 122.92, NMR (101 MHz, D₂O) δ = 78.9, 75.6, 62.1, 57.7, 50.7, 49.8, 48.9.

+

119.63, 78.62, 76.30, 66.67, 52.78, 44.54. HRMS (ESI-TOF): m/z HRMS (ESI-TOF): m/z calcd for C₇H₁₇N₂O₃177.1239 [M + H]⁺;

+

[M + H]⁺for C₁₄H₁₈N₃O₂calculated 260.1393; observed found 177.1226.

260.1381.

(2R,3R,4R)-2-(((3-Hydroxypropyl)amino)methyl)pyrrolidine-

(2R,3R,4R)-3,4-Dihydroxy-2-(1-methyl-1H-benzo[d]imidazol- 3,4-diol (25f). The precursor (2R,3R,4R)-N-benzyloxycarbonyl-

2-yl)pyrrolidine (23d). The precursor (2R,3R,4R)-N-benzyloxy- 3,4-dihydroxy-2-(((3-hydroxypropyl)amino)methyl)pyrrolidine

carbonyl-3,4-dihydroxy-2-(1-methyl-1H-benzo[d]imidazol-2-yl)- (172 mg, 70% yield) was purified by HPLC: gradient elution

pyrrolidine (184 mg, 67% yield) was prepared as follows. The from 0% to 60% MeOH in 40 min. HPLC analysis: gradient

aldehyde 7 dissolved in MeOH (see above in the general pro- elution from 2% to 62% B in 30 min; t_R= 17.0 min. The title

cedure) was treated with the amine (5 equiv. mol⁻¹aldehyde) compound (103 mg, 91% yield) was prepared according to the

in glacial acetic acid (5 equiv. mol⁻¹aldehyde) and stirred for general procedure described above. [α]_D²²= +6.7 (c 0.9 in

5 h at room temperature. The precursor was purified by flash MeOH). ¹H NMR (500 MHz, D₂O) δ = 4.21 (dt, ³J(H,H) = 5.5,

3

chromatography on silica (7 : 3 AcOEt–hexane). HPLC analysis: 3.4 Hz, 1H), 3.96 (t, ³J(H,H) = 3.8 Hz, 1H), 3.68 (t, J(H,H) = 6.1

gradient elution from 2% to 62% B in 30 min; t_R= 22.2 min. Hz, 2H), 3.42 (dt, ³J(H,H) = 8.9, 4.2 Hz, 1H), 3.38–3.30 (m, 2H),

The title compound (136 mg, 78% yield) was prepared by 3.22 (dd, ³J(H,H) = 13.1, 8.7 Hz, 1H), 3.14 (m, 2H), 3.02 (dd,

removing the Cbz group by catalytic hydrogenation according ³J(H,H) = 12.3, 3.3 Hz, 1H), 1.89 (m, 2H). ¹³C NMR (101 MHz,

to the general procedure described above. HPLC purification: D₂O) δ = 78.78, 75.31, 61.03, 58.85, 50.64, 48.68, 46.05, 27.92.

gradient elution from 0 to 60% B in 40 min. HPLC analysis: HRMS (ESI-TOF): m/z calcd for C₈H₁₉N₂O₃191.1395 [M + H⁺];

+

gradient elution from 2% to 62% B in 40 min; t_R= 12.0 min. found 191.1375.

[α]²_D²= −2.4 (c 1 in MeOH). ¹H NMR (500 MHz, CD₃OD) δ =

(2R,3R,4R)-2-((((S)-1-Hydroxypropan-2-yl)amino)methyl)pyrro-

7.70 (d, J = 8.3 Hz, 1H), 7.59 (d, J = 8.2 Hz, 1H), 7.42–7.36 (m, lidine-3,4-diol (25g). The precursor (2R,3R,4R)-N-benzyloxy-

1H), 7.36–7.30 (m, 1H), 5.03 (d, J = 3.1 Hz, 1H), 4.53 (t, J = carbonyl-3,4-dihydroxy-2-((((S)-1-hydroxypropan-2-yl)amino)methyl)-

2.5 Hz, 1H), 4.37 (dt, J = 4.7, 2.4 Hz, 1H), 3.95 (s, 3H), 3.75 (dd, pyrrolidine (175 mg, 72% yield) was purified by HPLC: gradi-

J = 12.0, 4.6 Hz, 1H), 3.59 (dd, J = 11.9, 2.3 Hz, 1H). ¹³C NMR ent elution from 0% to 60% MeOH in 40 min. HPLC analysis:

(101 MHz, CD₃OD) δ = 149.2, 137.2, 125.2, 124.6, 119.4, 111.6, gradient elution from 2% to 62% B in 30 min; t_R= 18.0 min.

80.8, 76.6, 62.3, 52.8, 30.9. HRMS (ESI-TOF): m/z [M + H]⁺for The title compound (100 mg, 92% yield) was prepared accord-

C₁₂H₁₆N₃O₂⁺calculated 234.1237; observed 234.1235.

ing to the general procedure described above. [α]²_D²= +14.0

1

3

(2R,3R,4R)-2-(Aminomethyl)-1-(quinolin-3-yl)pyrrolidine-3,4- (c 1.5 in MeOH). H NMR (500 MHz, D₂O) δ = 4.39 (dt, J(H,H)

3

diol (23e). The title compound (7 mg, 5% yield) was obtained = 4.1, 1.9 Hz, 1H), 4.30 (t, J(H,H) = 2.4 Hz, 1H), 3.94 (td, J(H,

after treatment of the precursor (2R,3R,4R)-N-benzyloxycarb- H) = 6.4, 2.9 Hz, 1H), 3.87 (dd, ³J(H,H) = 12.7, 3.6 Hz, 1H), 3.66

onyl-3,4-dihydroxy-2-((quinolin-3-ylamino)methyl)pyrrolidine with (m, 4H), 3.53 (ddd, ³J(H,H) = 10.2, 6.6, 3.4 Hz, 1H), 3.48 (d,

H₂in the presence of Pd/C. HPLC purification: gradient ³J(H,H) = 12.7 Hz, 1H), 1.33 (d, ³J(H,H) = 6.8 Hz, 3H). ¹³C NMR

elution from 0 to 60% B in 40 min. HPLC analysis: gradient (101 MHz, D₂O) δ = 77.55, 73.70, 62.03, 60.93, 56.70, 51.24,

+

elution from 2% to 62% B in 40 min; t_R= 10.9 min. [α]_D²²

=

44.53, 12.63. HRMS (ESI-TOF): m/z calcd for C₈H₁₉N₂O₃

−28.0 (c 0.5 in MeOH). ¹H NMR (400 MHz, CD₃OD) δ = 8.84 (d, 191.1395 [M + H⁺]; found 191.1375.

J = 2.9 Hz, 1H), 8.13 (d, J = 2.8 Hz, 1H), 8.08–8.02 (m, 2H),

(2R,3R,4R)-2-((((S)-1-Hydroxybutan-2-yl)amino)methyl)pyrro-

7.80–7.70 (m, 2H), 4.37 (d, J = 3.8 Hz, 1H), 4.35 (s, 1H), 4.15 lidine-3,4-diol (25h). The precursor (2R,3R,4R)-N-benzyloxycar-

(dd, J = 7.1, 1.8 Hz, 1H), 3.88–3.74 (m, 2H), 3.67 (dd, J = 13.8, bonyl-3,4-dihydroxy-2-((((S)-1-hydroxybutan-2-yl)amino)methyl)-

7.2 Hz, 1H), 3.37 (dd, J = 13.9, 2.0 Hz, 1H). ¹³C NMR (101 MHz, pyrrolidine (122 mg, 64% yield) was purified by HPLC: gradi-

CD₃OD) δ = 143.5, 135.6, 134.95, 131.5, 130.7, 130.7, 128.4, ent elution from 10% to 70% MeOH in 40 min. HPLC analysis:

122.7, 122.4, 80.7, 75.3, 66.6, 57.8, 39.5. HRMS (ESI-TOF): m/z gradient elution from 2% to 62% B in 30 min; t_R= 19.9 min.

+

[M + H]⁺for C₁₄H₁₇N₃O₂calculated 260.1399; observed The title compound (64 mg, 91% yield) was prepared accord-

260.1389.

DAB 2-aminomethyl alcohol derivatives 25. (2R,3R,4R)- (c 1.0 in MeOH). ¹H NMR (500 MHz, D₂O) δ = 4.23 (m, 1H),

ing to the general procedure described above. [α]²_D²= +16.1

3

2-(((2-Hydroxyethyl)amino)methyl)pyrrolidine-3,4-diol

(25e). 3.98 (t, J(H,H) = 3.5 Hz, 1H), 3.79 (dd, J(H,H) = 12.5, 3.7 Hz,

The precursor (2R,3R,4R)-N-benzyloxycarbonyl-3,4-dihydroxy- 1H), 3.64 (m, 1H), 3.44 (dt, ³J(H,H) = 8.9, 4.6 Hz, 1H), 3.38 (dd,

2-(((2-hydroxyethyl)amino)methyl)pyrrolidine (95 mg, 40% ³J(H,H) = 12.3, 5.3 Hz, 1H), 3.26 (dd, ³J(H,H) = 13.2, 5.0 Hz,

yield) was purified by HPLC: gradient elution 0% MeOH for 1H), 3.17 (dd, ³J(H,H) = 13.2, 8.4 Hz, 1H), 3.02 (m, 2H), 1.62

5 min, then from 0% to 70% MeOH in 35 min. HPLC analysis: (m, 2H), 0.93 (t, ³J(H,H) = 7.5 Hz, 3H). ¹³C NMR (101 MHz,

gradient elution from 2% to 62% B in 30 min; t_R= 16.7 min. D₂O) δ = 78.8, 75.5, 61.8, 60.6, 59.2, 50.4, 46.0, 21.0, 9.1. HRMS

The title compound (64 mg, 98% yield) was prepared accord- (ESI-TOF): m/z calcd for C₉H₂₁N₂O₃205.1552 [M + H]⁺; found

+

ing to the general procedure described above. [α]²_D²= +4.7 (c 1.0 205.1547.

1

in MeOH). H NMR (400 MHz, D₂O) δ = 4.21 (m, 1H), 3.97 (t,

(2R,3R,4R)-2-((((R)-1-Hydroxypentan-2-yl)amino)methyl)-

³J(H,H) = 3.5 Hz, 1H), 3.76 (t, J(H,H) = 5.3 Hz, 2H), 3.45 (m, pyrrolidine-3,4-diol (25i). The precursor (2R,3R,4R)-N-

3

2014 | Org. Biomol. Chem., 2013, 11, 2005–2021

This journal is © The Royal Society of Chemistry 2013

View Article Online

Organic & Biomolecular Chemistry

Paper

benzyloxycarbonyl-3,4-dihydroxy-2-((((R)-1-hydroxypentan-2-yl)- general procedure described above. [α]²_D²= +35.4 (c 0.9 in

1

amino)methyl)pyrrolidine (112 mg, 57 yield) was purified by MeOH). H NMR (400 MHz, D₂O) δ = 4.30 (s, 1H), 4.09 (s, 1H),

HPLC: gradient elution from 10% to 70% MeOH in 40 min. 3.94 (dd, J(H,H) = 12.3, 3.5 Hz, 1H), 3.70 (m, 2H), 3.51 (m, 2H),

3

HPLC analysis: gradient elution from 2% to 62% B in 30 min; 3.32 (d, J(H,H) = 12.9 Hz, 1H), 3.20 (t, J(H,H) = 9.4 Hz, 1H),

t_R= 22.0 min. The title compound (59 mg, 89% yield) was pre- 3.11 (dd, ³J(H,H) = 14.7, 5.4 Hz, 1H), 2.98 (m, 2H), 2.57 (m,

3

pared according to the general procedure described above. 2H), 1.85 (dd, J(H,H) = 13.2, 4.6 Hz, 1H), 1.62 (ddd, J(H,H) =

[α]_D²²= +1.05 (c 0.9 in MeOH). ¹H NMR (500 MHz, D₂O) δ = 4.31 25.0, 12.7, 4.0 Hz, 1H). ¹³C NMR (101 MHz, D₂O) δ = 77.0, 74.8,

(m, 1H), 4.16 (s, 1H), 3.85 (m, 1H), 3.70 (m, 2H), 3.53 (m, 2H), 73.0, 71.4, 65.2, 64.2, 58.3, 50.3, 48.9, 48.2, 29.1. HRMS

3.43 (dd, ³J(H,H) = 13.5, 8.3 Hz, 1H), 3.29 (m, 2H), 1.62 (dd, (ESI-TOF): m/z calcd for C₁₁H₂₃N₂O₅⁺263.1607 [M + H⁺]; found

³J(H,H) = 15.2, 7.5 Hz, 2H), 1.37 (m, 2H), 0.90 (t, ³J(H,H) = 263.1592.

7.3 Hz, 3H). ¹³C NMR (101 MHz, D₂O) δ = 78.0, 74.4, 62.0, 59.9,

58.6, 50.9, 45.1, 29.2, 18.1, 12.9. HRMS (ESI-TOF): m/z calcd for acid conjugates 28, 29, and 30. (7R,8R,8aR)-7,8-Dihydroxyhexa-

C₁₀H₂₃N₂O₃⁺219.1709 [M + H⁺]; found 219.1691.

hydropyrrolo[1,2-a]pyrazin-4(1H)-one (28m). The precursor

DAB and LAB fused 2-oxopiperazine derivatives and amino

(2R,3R,4R)-2-((((R)-1-Hydroxy-3-methylbutan-2-yl)amino)methyl)- (2R,3R,4R)-N-benzyloxycarbonyl-2-((glycineamidyl)methyl)-3,4-

pyrrolidine-3,4-diol (25j). The precursor (2R,3R,4R)-N-benzyl- dihydroxypyrrolidine (26m) (140 mg, 58% yield) was purified

oxycarbonyl-3,4-dihydroxy-2-((((R)-1-hydroxy-3-methylbutan-2-yl)- by HPLC: gradient elution 0% MeOH for 5 min, then from 0%

amino)methyl)pyrrolidine (94 mg, 47% yield) was purified by to 70% MeOH in 35 min. HPLC analysis: gradient elution from

HPLC: gradient elution from 10% to 70% MeOH in 40 min. 2% to 62% B in 30 min; t_R= 16.9 min. ¹H NMR (400 MHz,

HPLC analysis: gradient elution from 2% to 62% B in 30 min; D₂O) δ 7.47 (m, 5H, arom), 5.22 (m, 2H, OCH₂Ph), 4.26 (broad

t_R= 21.6 min. The title compound (50 mg, 94% yield) was pre- s, 1H, H-4), 4.13 (m, 2H, H-2-3), 3.88 (m, 3H, H-5-7-7′), 3.48

pared according to the general procedure described above. (m, 3H H-5′-6-6′). ¹³C NMR (101 MHz, D₂O) δ 168.2 (CONH₂),

[α]²_D²= +18.3 (c 0.9 in MeOH). ¹H NMR (500 MHz, D₂O) δ = 4.27 157.9 (COBn), 156.7 (COBn-rotamer), 135.8 (C-Ar), 135.4 (C-Ar-

(dt, ³J(H,H) = 5.1, 2.7 Hz, 1H), 4.08 (t, ³J(H,H) = 2.8 Hz, 1H), rotamer), 128.8 (C-Ar), 128.8 (C-Ar), 128.5 (C-Ar), 128.5 (C-Ar),

3

3.83 (dd, J(H,H) = 12.5, 3.9 Hz, 1H), 3.69 (dd, J(H,H) = 12.5, 127.9 (C-Ar), 78.3 (C-3 rotamer), 77.6 (C-3), 73.6 (C-4), 73.1 (C-4

3

6.8 Hz, 1H), 3.62 (dt, J(H,H) = 8.2, 4.2 Hz, 1H), 3.48 (dd, J(H, rotamer), 68.4 (CH₂Ph), 68.0 (CH₂Ph rotamer), 62.1 (C-2), 61.9

H) = 12.5, 5.0 Hz, 1H), 3.40 (dd, ³J(H,H) = 13.5, 4.8 Hz, 1H), (C-2 rotamer), 53.0 (C-5 rotamer), 52.4 (C-5), 49.6 (C-6), 48.7

3

3.31 (dd, J(H,H) = 13.5, 8.5 Hz, 1H), 3.20 (dd, J(H,H) = 12.5, (C-6 rotamer), 48.0 (C-7). The title compound (78 mg, 92%

2.4 Hz, 1H), 2.95 (m, 1H), 2.00 (dq, ³J(H,H) = 13.4, 6.8 Hz, 1H), yield) was prepared according to the general procedure

0.96 (dd, ³J(H,H) = 25.3, 6.9 Hz, 6H). ¹³C NMR (101 MHz, D₂O) described above. [α]²_D²= +2.3 (c 1.4 in MeOH). ¹H NMR

δ = 78.2, 74.8, 64.8, 62.4, 58.1, 50.6, 46.2, 27.1, 18.1, 17.0. (400 MHz, D₂O) δ 4.33 (dd, ³J(H,H) = 13.8, 7.0 Hz, 1H), 3.96

+

3

HRMS (ESI-TOF): m/z calcd for C₁₀H₂₃N₂O₃219.1709 [M + (t, J(H,H) = 6.7 Hz, 1H), 3.83 (m, 5H), 3.49 (m, 1H), 3.15 (t, J

H⁺]; found 219.1691. (H,H) = 11.3 Hz, 1H). ¹³C NMR (101 MHz, D₂O) δ 164.3, 77.6,

(2R,3R,4R)-2-(((1,3-Dihydroxypropan-2-yl)amino)methyl)- 72.7, 57.9, 48.8, 44.4, 43.5. HRMS-ESI: m/z calcd for C₇H₁₃N₂O₃

pyrrolidine-3,4-diol (25k). The precursor (2R,3R,4R)-N-benzyloxy- 173.0926 [M + H⁺]; found: 173.0923.

carbonyl-2-(((1,3-dihydroxypropan-2-yl)amino)methyl)-3,4-di-

(3S,7R,8R,8aR)-7,8-Dihydroxy-3-methylhexahydropyrrolo[1,2-

hydroxypyrrolidine (126 mg, 66 yield) was purified by HPLC: a]pyrazin-4(1H)-one (28n). The precursor (2R,3R,4R)-N-benzyl-

gradient elution from 10% to 70% MeOH in 40 min. HPLC oxycarbonyl-2-(((S)-alanineamidyl)methyl)-3,4-dihydroxypyrro-

analysis: gradient elution from 2% to 62% B in 30 min; t_R

=

lidine (26n) (110 mg, 58% yield) was purified by HPLC:

17.1 min. The title compound (78 mg, 99% yield) was prepared gradient elution 0% to 70% MeOH in 40 min. HPLC analysis:

according to the general procedure described above. [α]_D²²

=

gradient elution from 10% to 70% B in 30 min; t_R= 13.5 min.

1

+15.2 (c 1.2 in MeOH). H NMR (500 MHz, D₂O) δ = 4.29 (dt, ¹H NMR (400 MHz, D₂O) δ 7.47 (m, 5H, Ar), 5.21 (m, 2H,

3

³J(H,H) = 5.0, 2.6 Hz, 1H), 4.08 (t, J(H,H) = 2.7 Hz, 1H), 3.70 OCH₂Ph), 4.25 (br s, 1H, H-4), 4.18 (s, 1H, H-3 rotamer), 4.12

(dd, ³J(H,H) = 11.8, 4.4 Hz, 2H), 3.59 (m, 3H), 3.52 (dd, ³J(H,H) (br s, 2H, H-3-H-2), 4.05 (m, 2H, H-2-rotamer-H-7), 3.91 (m,

= 12.6, 4.8 Hz, 1H), 3.30 (d, ³J(H,H) = 2.4 Hz, 1H), 3.25 (dd, 1H, H-7-rotamer), 3.84 (td, J = 12.2, 5.0 Hz, 2H, H-5;H-5-

³J(H,H) = 13.4, 5.0 Hz, 1H), 3.12 (dd, ³J(H,H) = 13.4, 8.9 Hz, rotamer), 3.52 (d, J = 12.5 Hz, 1H, H-5′), 3.48 (d, J = 12.6 Hz,

1H), 2.93 (m, 1H). ¹³C NMR (101 MHz, D₂O) δ = 77.5, 74.5, 1H, H-5′ rotamer), 3.44 (br s, 2H, H-6-H-6 rotamer), 3.36 (br s,

64.3, 59.9, 59.8, 50.2, 45.9. HRMS (ESI-TOF): m/z calcd for 2H, H-6′-H-6′ rotamer), 1.53 (d, J = 7.0 Hz, 3H, H-8), 1.43 (d, J =

C₈H₁₉N₂O₄⁺207.1316 [M + H⁺]; found 207.1333.

7.0 Hz, 3H, H-8-rotamer). ¹³C NMR (101 MHz, D₂O) δ 172.2

(2R,3R,4R)-1-(((2R,3R,4R)-3,4-Dihydroxypyrrolidin-2-yl)methyl)- (CONH₂), 157.8 (COBn), 156.6 (COBn-rotamer), 135.9 (C-Ar),

2-(hydroxymethyl)piperidine-3,4-diol (25l). The precursor 135.5 (C-Ar-rotamer), 128.9 (C-Ar), 128.8 (C-Ar), 128.5 (C-Ar),

(2R,3R,4R)-N-benzyloxycarbonyl-2-(((2R,3R,4R)-3,4-dihydroxy-2- 128.5 (C-Ar), 127.9 (C-Ar), 78.1 (C-3-rotamer), 77.4 (C-3), 73.6

(hydroxymethyl)piperidin-1-yl)methyl)-3,4-dihydroxypyrrolidine (C-4), 73.1 (C-4-rotamer), 68.3 (CH₂Ph-rotamer), 68.1 (CH₂Ph),

(102 mg, 52% yield) was purified by HPLC: gradient elution 62.2 (C-2), 62.0 (C-2-rotamer), 56.2 (C-7-rotamer), 56.2 (C-7),

from 0% to 70% MeOH in 40 min. HPLC analysis: gradient 52.9 (C-5), 52.3 (C-5-rotamer), 47.6 (C-6), 46.9 (C-6-rotamer),

elution from 2% to 62% B in 30 min; t_R= 17.3 min. The title 15.2 (C-8). The title compound (63 mg, 95% yield) was pre-

compound (60 mg, 79% yield) was prepared according to the pared according to the general procedure described above.

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2015

View Article Online

Paper

Organic & Biomolecular Chemistry

1

[α]²_D²= +22.2 (c 1.2 in MeOH). H NMR (400 MHz, D₂O) δ 4.34 = 7.30 (m, 10H, Ar), 5.12 (m, 2H, CH₂Ph), 4.29 (t, J = 6.6 Hz,

3

(dd, J(H,H) = 13.7, 6.4 Hz, 1H), 4.22 (q, J(H,H) = 7.3 Hz, 1H), 1H, H-7), 4.04 (br s, 1H, H-4), 3.93 (m, 2H, H-2-H-3), 3.77 (s,

4.04 (m, 1H), 3.85 (m, 3H), 3.51 (dd, ³J(H,H) = 12.6, 6.3 Hz, 3H, OCH₃), 3.73 (dd, J = 11.6, 4.5 Hz, 1H, H-5), 3.48 (dd, J =

1H), 3.40 (m, 1H), 1.61 (d, ³J(H,H) = 7.3 Hz, 3H). ¹³C NMR 13.0, 2.8 Hz, 1H, H-6), 3.43 (d, J = 12.0 Hz, 1H, H-5′), 3.36 (m,

(101 MHz, D₂O) δ 166.1, 77.5, 72.8, 57.3, 51.2, 49.2, 40.5, 14.2. 1H, H-6′), 3.22 (d, J = 6.6 Hz, 2H, H-8-H-8′). ¹³C NMR

HRMS-ESI: m/z calcd for C₈H₁₅N₂O₃187.1083 [M + H⁺]; found: (101 MHz, CD₃OD) δ = 173.87 (CONH₂), 158.95 (COBn), 137.62

187.1089.

(C-Ar), 135.15 (C-Ar), 130.44 (2C-Ar), 130.14 (2C-Ar), 129.60

(3S,7R,8R,8aR)-7,8-Dihydroxy-3-isobutylhexahydropyrrolo- (2C-Ar), 129.32 (2C-Ar), 129.06 (2C-Ar), 79.54 (C-3), 75.32 (C-4),

[1,2-a]pyrazin-4(1H)-one (28p). The precursor (2R,3R,4R)-N-benzyl- 68.89 (CH₂Ph), 64.86 (C-2), 62.83 (C-7), 54.50 (C-5), 53.53

oxycarbonyl-2-(((S)-leucineamidyl)methyl)-3,4-dihydroxypyrroli- (OCH₃), 50.85 (C-6), 37.20 (C-8). The title compound (100 mg,

dine (26p) (132 mg, 62% yield) was purified by HPLC: gradient 95% yield) was prepared according to the general procedure

elution 0% to 70% MeOH in 40 min. HPLC analysis: gradient described above. [α]²_D²= −11.4 (c 1.2 in MeOH). ¹H NMR

1

3

elution from 10% to 70% B in 30 min; t_R= 18.3 min. H NMR (400 MHz, D₂O) δ 7.37 (m, 5H), 4.41 (dd, J(H,H) = 7.5, 5.5 Hz,

(400 MHz, D₂O) δ 7.46 (m, 5H, Ar), 5.20 (m, 2H, OCH₂Ph), 4.24 1H), 4.28 (dd, ³J(H,H) = 12.3, 6.1 Hz, 1H), 3.80 (m, 3H), 3.65

(m, 1H, H-4), 4.18 (s, 1H, H-3-rotamer), 4.10 (br s, 2H, H-2- (m, 1H), 3.52 (dd, ³J(H,H) = 12.8, 5.8 Hz, 1H), 3.43 (dd, ³J(H,H)

3

H-3), 4.03 (br s, 1H, H-2-rotamer), 3.94 (t, J = 7.0 Hz, 1H, H-7), = 15.1, 5.3 Hz, 1H), 3.31 (dd, J(H,H) = 15.1, 7.7 Hz, 1H), 2.91

3.82 (m, 2H, H-5-H-7-rotamer), 3.50 (m, 2H, H-5′-H-6), 3.36 (m, (m, 1H). ¹³C NMR (101 MHz, D₂O) δ 164.6, 134.0, 129.3, 129.2,

2H, H-6′-H-6-rotamer), 3.20 (dd, J = 13.1, 6.6 Hz, 1H, H-6′- 128.1, 77.7, 72.8, 57.2, 55.8, 49.3, 41.5, 34.5. HRMS-ESI: m/z

rotamer), 1.62 (m, 3H, H-8-H8′-H-9), 0.94 (m, 6H, CH₃). ¹³C calcd for C₁₄H₁₉N₂O₃263.1396 [M + H⁺]; found: 263.1377.

NMR (101 MHz, D₂O) δ 171.3 (CONH₂), 158.0 (COBn), 156.6

1-(3-((3S,7R,8R,8aR)-7,8-Dihydroxy-4-oxooctahydropyrrolo-

(COBn-rotamer), 135.8 (C-Ar), 135.3 (C-Ar-rotamer), 128.9 [1,2-a]pyrazin-3-yl)propyl)guanidine (28u). The precursor

(C-Ar), 128.8 (C-Ar), 128.6 (C-Ar), 128.5 (C-Ar), 127.9 (C-Ar), (2R,3R,4R)-N-benzyloxycarbonyl-2-(((S)-arginineamidyl)methyl)-

78.3 (C-3 rotamer), 77.5 (C-3), 73.4 (C-4), 73.0 (C-4 rotamer), 3,4-dihydroxypyrrolidine (26u) (129 mg, 55% yield) was puri-

68.4 (CH₂Ph rotamer), 68.1 (CH₂Ph), 62.2 (C-2), 62.1 (C-2 fied by HPLC: gradient elution 0% MeOH for 5 min, then from

rotamer), 59.8 (C-7 rotamer), 59.6 (C-7), 53.0 (C-5 rotamer), 0% to 70% MeOH in 40 min. HPLC analysis: gradient elution

52.3 (C-5), 48.5 (C-6), 47.4 (C-6 rotamer), 38.9 (C-8), 38.7 (C-8 from 10% to 70% B in 30 min; t_R= 12.4 min. ¹H NMR

rotamer), 24.0 (C-9 rotamer), 24.0 (C-9), 21.8 (C-10 rotamer), (400 MHz, D₂O) δ 7.45 (m, 5H, Ar), 5.20 (m, 2H, OCH₂Ph), 4.25

21.5 (C-10), 21.3 (C-11), 21.0 (C-11 rotamer). The title com- (m, 1H, H-4), 4.18 (s, 1H, H-3 rotamer), 4.10 (br s, 2H, H-2-

pound (94 mg, 96% yield) was prepared according to the H-3), 4.06 (br s, 1H, H-2 rotamer), 3.97 (t, J = 6.3 Hz, 1H, H-7),

general procedure described above. [α]²_D²= −9.0 (c 1.0 in 3.85 (m, 2H, H-5-H-7 rotamer), 3.44 (m, 3H, H-5′-H-6-H-6′),

MeOH). ¹H NMR (400 MHz, D₂O) δ 4.32 (dd, ³J(H,H) = 13.3, 3.19 (m, 2H, H-10-H-10′), 1.93 (m, 1H, H-8), 1.64 (m, 3H, H-8′-

6.1 Hz, 1H), 4.00 (m, 2H), 3.81 (m, 1H), 3.50 (dd, ³J(H,H) = H-9-H-9′). ¹³C NMR (101 MHz, D₂O) δ 170.4 (CONH₂), 158.1

3

12.7, 5.9 Hz, 1H), 3.30 (m, 1H), 1.81 (m, 1H), 0.98 (t, J(H,H) = (COBn), 156.7 (CvNH), 135.9 (C-Ar), 135.4 (C-Ar rotamer),

5.5 Hz, 1H). ¹³C NMR (101 MHz, D₂O) δ 166.6, 77.7, 72.9, 57.7, 128.9 (C-Ar), 128.8 (C-Ar), 128.6 (C-Ar), 128.5 (C-Ar), 127.8

53.6, 49.3, 41.1, 37.9, 24.3, 21.7, 20.6. HRMS-ESI: m/z calcd for (C-Ar), 78.2 (C-3 rotamer), 77.4 (C-3), 73.4 (C-4), 73.0 (C-4

C₁₁H₂₁N₂O₃229.1552 [M + H⁺]; found: 229.1538.

rotamer), 68.3 (CH₂Ph rotamer), 68.1 (CH₂Ph), 62.2 (C-2), 62.0

(3S,7R,8R,8aR)-3-Benzyl-7,8-dihydroxyhexahydropyrrolo[1,2-a]- (C-2 rotamer), 60.4 (C-7 rotamer), 60.2 (C-7), 53.0 (C-5

pyrazin-4(1H)-one (28q). The precursor (2R,3R,4R)-N-benzyloxy- rotamer), 52.3 (C-5), 48.6 (C-6), 47.6 (C-6 rotamer), 40.2 (C-10),

carbonyl-2-(((S)-phenylalanineamidyl)methyl)-3,4-dihydroxy- 26.8 (C-8), 26.7 (C-8 rotamer), 23.3 (C-9 rotamer), 23.3 (C-9).

pyrrolidine (26q) (165 mg, 70% yield) was purified by HPLC: The title compound (100 mg, 92% yield) was prepared accord-

0% to 70% MeOH in 40 min. HPLC analysis: gradient elution ing to the general procedure described above. [α]²_D²= −2.0

from 10% to 70% B in 30 min; t_R= 20.0 min. ¹H NMR (c 1.0 in MeOH). ¹H NMR (400 MHz, D₂O) δ 4.32 (dd, ³J(H,H) =

(400 MHz, CD₃OD) δ = 7.33 (m, 10H, Ar), 5.06 (q, J = 12.3 Hz, 12.6, 6.5 Hz, 1H), 4.03 (dd, ³J(H,H) = 11.9, 5.7 Hz, 2H), 3.82 (m,

2H, OCH₂Ph), 4.15 (t, J = 7.0 Hz, 1H, H-7), 4.05 (br s, 1H, H-4), 3H), 3.53 (dd, ³J(H,H) = 12.7, 5.7 Hz, 1H), 3.26 (m, 3H), 2.14

3.93 (br s, 2H, H-2-H-3), 3.70 (dd, J = 11.6, 4.3 Hz, 1H, H-5), (m, 1H), 1.91 (m, 1H), 1.78 (m, 2H). ¹³C NMR (101 MHz, D₂O)

3.43 (m, 3H, H-5′-H-6-H-6′), 3.19 (ddd, J = 38.2, 14.1, 7.0 Hz, δ 165.8, 156.7, 77.7, 72.9, 57.8, 54.7, 49.3, 41.6, 40.4, 26.4, 24.8.

2H, CH₂Ph). ¹³C NMR (101 MHz, CD₃OD) δ = 170.6 (CONH₂), HRMS-ESI: m/z calcd for C₁₁H₂₂N₅O₃272.1723 [M + H⁺];

159.0 (COBn), 137.5 (C-Ar), 135.0 (C-Ar), 130.6 (2C-Ar), 130.11 found: 272.1726.

(2C-Ar), 129.6 (C-Ar), 129.3 (C-Ar), 129.1 (C-Ar), 128.9 (C-Ar),

(1R,2R,5aS,10aR)-1,2-Dihydroxyoctahydrodipyrrolo[1,2-a:1′,2′-

79.4 (C-3), 75.11 (C-4), 68.9 (OCH₂Ph), 64.3 (C-2), 63.4 (C-7), d]pyrazin-5(1H)-one (28v). The precursor (2R,3R,4R)-N-benzyl-

54.2 (C-5), 51.2 (C-6), 37.9 (CH₂Ph). The precursor (2R,3R,4R)- oxycarbonyl-2-(((S)-prolineamidyl)methyl)-3,4-dihydroxypyrrolidine

N-benzyloxycarbonyl-3,4-dihydroxy-2-((((S)-1-methoxy-1-oxo-3- (26v) (128 mg, 63% yield) was purified by HPLC: gradient

phenylpropan-2-yl)amino)methyl)pyrrolidine (26r) (230 mg, elution 0% to 70% MeOH in 40 min. HPLC analysis: gradient

70% yield) was purified by HPLC: gradient elution 10% to 80% elution from 2% to 62% B in 30 min; t_R= 18.0 min. Assigned

1

B during 40 min. HPLC analysis: gradient elution from 10% to the major rotamer: H NMR (500 MHz, CD₃OD) δ 7.44 (m, 5H,

1

70% B in 30 min; t_R= 23.5 min. H NMR (400 MHz, CD₃OD) δ Ar), 5.23 (m, 2H, OCH₂Ph), 4.28 (s, 1H, H-7), 4.16 (m, 2H, H-3-

2016 | Org. Biomol. Chem., 2013, 11, 2005–2021

View Article Online

Organic & Biomolecular Chemistry

Paper

H-4), 4.00 (t, J = 5.6 Hz, 1H, H-2), 3.87 (br s, 1H, H-10), 3.75 (m, 2H, H-8-H-8′), 1.48 (s, 9H, 3CH₃). ¹³C NMR (101 MHz,

(m, 2H, H-5-H-6), 3.53 (m, 2H, H-5′-H-6′), 3.38 (m, 1H, H-10′), CD₃OD) δ 170.2 (CONH₂), 170.1 (COO^tBu), 158.9 (COBn), 137.5

2.59 (m, 1H, H-8), 2.23 (m, 1H, H-9), 2.12 (m, 2H, H-8′-H-9′). (C-Ar), 129.6 (C-Ar), 129.6 (C-Ar), 129.4 (C-Ar), 129.3 (C-Ar),

¹³C NMR (101 MHz, CD₃OD) δ 171.0 (CONH₂), 159.8 (COBn), 129.0 (C-Ar), 84.1 (C-CH₃), 79.4 (C-3), 75.3 (C-4), 68.8

137.8 (C-Ar), 130.1 (C-Ar), 129.9 (C-Ar), 129.6 (C-Ar), 129.3 (OCH₂Ph), 64.4 (C-2), 58.4 (C-7), 54.3 (C-5), 51.0 (C-6), 36.3

(C-Ar), 129.1 (C-Ar), 78.8 (C-3), 76.0 (C-4), 70.5 (C-7) 68.7 (C-8), 28.2 (3CH₃). The title compound (95 mg, 93% yield) was

(OCH₂Ph), 63.7 (C-2), 59.5 (C-6), 55.4 (C-10), 54.1 (C-5), 30.3 prepared according to the general procedure described above.

1

(C-8), 24.2 (C-9). The title compound (90 mg, 97% yield) was [α]²_D²= +16.6 (c 0.9 in MeOH). H NMR (400 MHz, D₂O) δ 4.36

prepared according to the general procedure described above. (dt, ³J(H,H) = 4.4, 2.3 Hz, 1H), 4.14 (t, ³J(H,H) = 2.3 Hz, 1H),

3

[α]²_D²= −19.0 (c 1 in MeOH) of the mixture. (major) ¹H NMR 3.62 (m, 3H), 3.42 (dd, J(H,H) = 12.6, 1.8 Hz, 1H), 3.13 (dd, J

(400 MHz, D₂O) δ 4.38 (m, 1H), 4.33 (dd, ³J(H,H) = 13.7, 6.9 (H,H) = 13.3, 5.4 Hz, 1H), 3.05 (dd, ³J(H,H) = 13.3, 9.0 Hz, 1H),

Hz, 1H), 3.99 (m, 1H), 3.93 (dd, ³J(H,H) = 12.1, 2.7 Hz, 1H), 2.74 (d, ³J(H,H) = 6.3 Hz, 2H), 1.47 (s, 9H). ¹³C NMR (101 MHz,

3.86 (m, 1H), 3.85 (m, 1H), 3.83 (m, 1H), 3.47 (dd, ³J(H,H) = D₂O) δ 177.7, 172.3, 83.5, 77.0, 74.5, 65.4, 57.7, 50.3, 46.4, 37.8,

3

12.6, 6.8 Hz, 1H), 3.39 (m, 1H), 3.23 (t, J(H,H) = 11.4 Hz, 1H), 27.3. HRMS-ESI: m/z calcd for C₁₃H₂₆N₃O₅304.1872 [M + H⁺];

2.55 (m, 1H), 2.24 (m, 1H), 2.20 (m, 1H), 2.09 (m, 1H). ¹³C found: 304.1869.

NMR (101 MHz, D₂O) δ 165.7, 77.0, 72.6, 62.1, 58.2, 56.9, 50.6,

48.7, 27.4, 21.8. (minor) ¹H NMR (400 MHz, D₂O) δ 4.40 (m, (1H)-one (29m). The precursor (2S,3S,4S)-N-benzyloxycarbonyl-

1H), 4.22 (m, 1H), 4.07 (m, 1H), 4.04 (m, 1H), 3.83 (m, 1H), 2-((glycineamidyl)methyl)-3,4-dihydroxypyrrolidine (27m)

(7S,8S,8aS)-7,8-Dihydroxyhexahydropyrrolo[1,2-a]pyrazin-4-

3.58 (m, 1H), 3.52 (d, ³J(H,H) = 14.0 Hz, 1H), 3.47 (m, 1H), 3.33 (147 mg, 60% yield) was purified by HPLC: gradient elution

(m, 1H), 3.32 (m, 1H), 2.53 (m, 1H), 2.10 (m, 1H), 2.11 (m, 1H), 0% MeOH for 5 min, then from 0% to 70% MeOH in 35 min.

1.98 (m, 1H). ¹³C NMR (101 MHz, D₂O) δ 168.2, 74.1, 68.1, HPLC analysis: identical to that 26m. ¹H and ¹³C NMR

61.0, 52.7, 51.8, 51.6, 48.5, 29.5, 23.6. HRMS-ESI: m/z calcd for matched those listed above for compound 26m. The title com-

C₁₀H₁₇N₂O₃213.1239 [M + H⁺]; found: 213.1226.

pound (100 mg, 99% yield) was prepared according to the

(2R,3R,4R)-2-(((S)-Valineamidyl)methyl)-3,4-dihydroxypyrro- general procedure described above. [α]²_D²= −2.5 (c 2.0 in

lidine (30o). The precursor (2R,3R,4R)-N-benzyloxycarbonyl-2- MeOH). ¹H NMR (400 MHz, D₂O) δ 4.31 (dd, ³J(H,H) = 14.3, 7.1

3

(((S)-valineamidyl)methyl)-3,4-dihydroxypyrrolidine

(26o) Hz, 1H), 3.94 (t, J(H,H) = 6.2 Hz, 1H), 3.83 (m, 4H), 3.47 (dd,

(104 mg, 51% yield) was purified by HPLC: gradient elution: ³J(H,H) = 12.5, 6.9 Hz, 1H), 3.18 (m, 1H). ¹³C NMR (101 MHz,

0% MeOH for 5 min, then from 10% to 80% MeOH in 40 min. D₂O) δ 163.3, 77.5, 72.6, 57.4, 48.8, 43.9, 43.3. HRMS-ESI: m/z

HPLC analysis: gradient elution from 10% to 70% B in 30 min; calcd for C₇H₁₃N₂O₃173.0926 [M + H⁺]; found: 173.0930.

1

t_R= 16.5 min. H NMR (400 MHz, CD₃OD) δ 7.35 (m, 5H, Ar),

(3S,7S,8S,8aS)-7,8-Dihydroxy-3-methylhexahydropyrrolo[1,2-a]-

5.19 (s, 2H, OCH₂Ph), 4.09 (br s, 1H, H-4), 3.99 (m, 2H, H-2- pyrazin-4(1H)-one (29n). The precursor (2S,3S,4S)-N-benzyloxy-

H-3), 3.75 (dd, J = 11.5, 4.3 Hz, 1H, H-5), 3.68 (d, J = 5.8 Hz, carbonyl-2-(((S)-alanineamidyl)methyl)-3,4-dihydroxypyrrolidine

1H, H-7), 3.49 (m, 2H, H-5′-H-6), 3.32 (m, 1H, H-6′), 2.20 (td, (27n) (50 mg, 44% yield) was purified by HPLC: gradient

J = 13.5, 6.8 Hz, 1H, H-8), 1.07 (m, 6H, 2CH₃). ¹³C NMR elution 0% to 70% B during 40 min. HPLC analysis: gradient

1

(101 MHz, CD₃OD) δ 170.1 (CONH₂), 159.3 (COBn), 137.5 elution from 10% to 70% B in 30 min; t_R= 13.4 min. H NMR

(C-Ar), 129.6 (2C-Ar), 129.3 (C-Ar), 129.1 (2C-Ar), 79.5 (C-3), (400 MHz, D₂O) δ 7.30 (m, 5H, Ar), 5.05 (d, J = 5.7 Hz, 2H,

75.0 (C-4), 69.1 (OCH₂Ph), 68.0 (C-7), 64.4 (C-2), 54.3 (C-5), 51.8 OCH₂Ph), 4.11 (m, 1H, H-4), 4.08 (m, 1H, H-4-rotamer), 4.02

(C-6), 31.1 (C-8), 18.6 (CH₃), 18.5 (CH₃). The title compound (s, 1H, H-3-rotamer), 3.93 (m, 3H, H-2-H-3-H-7), 3.77 (q, J = 7.0

(65 mg, 87% yield) was prepared according to the general pro- Hz, 1H, H-7-rotamer), 3.68 (dt, J = 11.0, 5.3 Hz, 1H, H-5), 3.36

1

cedure described above. [α]²_D²= +8.0 (c 1.0 in MeOH). H NMR (m, 2H, H-5′-H-6), 3.15 (ddd, J = 25.4, 13.1, 7.1 Hz, 1H, H-6′),

3

(400 MHz, D₂O) δ 4.35 (dt, J(H,H) = 4.4, 2.2 Hz, 1H), 4.14 (t, 1.41 (d, J = 7.1 Hz, 3H, CH₃), 1.24 (d, J = 7.1 Hz, 3H, CH₃

3

³J(H,H) = 2.3 Hz, 1H), 3.60 (m, 2H), 3.41 (dd, J(H,H) = 12.6, rotamer). ¹³C NMR (101 MHz, D₂O)

δ 172.0 (CONH₂),

1.7 Hz, 1H), 3.05 (m, 2H), 2.97 (dd, ³J(H,H) = 13.3, 8.5 Hz, 1H), 171.8 (CONH₂rotamer), 158.0 (COBn), 156.5 (COBn-rotamer),

3

1.93 (tt, J(H,H) = 13.6, 6.8 Hz, 1H), 0.98 (dd, J(H,H) = 8.7, 6.9 135.8 (C-Ar), 135.3 (C-Ar-rotamer), 128.9 (C-Ar), 128.7 (C-Ar),

Hz, 6H). ¹³C NMR (101 MHz, D₂O) δ 179.0, 77.1, 74.5, 67.9, 128.6 (C-Ar), 128.5 (C-Ar), 127.9 (C-Ar), 78.2 (C-3-rotamer),

65.6, 50.3, 47.3, 31.0, 18.4, 18.1. HRMS-ESI: m/z calcd for 77.6 (C-3), 73.5 (C-4-rotamer), 73.0 (C-4), 68.4 (OCH₂Ph-

C₁₀H₂₂N₃O₃232.1661 [M + H⁺]; found: 232.1642.

rotamer), 68.1 (CH₂Ph), 62.1 (C-2), 62.1 (C-2-rotamer),

(2R,3R,4R)-2-(((S)-Aspartic(βtert-butyl)amidyl)methyl)-3,4- 56.4 (C-7-rotamer), 56.2 (C-7), 53.1 (C-5-rotamer), 52.3 (C-5),

dihydroxypyrrolidine (30t). The precursor (2R,3R,4R)-N-benzyl- 48.3 (C-6), 47.4 (C-6-rotamer), 15.4 (C-8), 15.2 (C-8-rotamer).

oxycarbonyl-2-(((S)-aspartic(β^tBu)amidyl)methyl)-3,4-dihydroxy- The title compound (45 mg, 99% yield) was prepared accord-

pyrrolidine (26t) (138 mg, 56% yield) was purified by HPLC: ing to the general procedure described above. [α]²_D²= +26.0

gradient elution 10% to 80% MeOH in 40 min. HPLC analysis: (c 1.0 in MeOH). ¹H NMR (400 MHz, D₂O) δ 4.34 (dd, ³J(H,H) =

3

gradient elution from 10% to 70% B in 30 min; t_R= 20.8 min. 14.2, 7.3 Hz, 1H), 4.09 (q, J(H,H) = 7.2 Hz, 1H), 3.91 (m, 3H),

3

¹H NMR (400 MHz, CD₃OD) δ 7.36 (m, 5H, Ar), 5.18 (m, 2H, 3.82 (dd, J(H,H) = 12.7, 8.0 Hz, 1H), 3.50 (dd, J(H,H) = 12.7,

OCH₂Ph), 4.07 (m, 2H, H-4-H-7), 3.99 (br s, 2H, H-2-H-3), 3.76 6.9 Hz, 1H), 3.31 (m, 1H), 1.59 (d, J(H,H) = 7.2 Hz, 3H). ¹³C

3

(dd, J = 11.6, 4.5 Hz, 1H, H-5), 3.42 (m, 3H, H-5′-H-6-H-6′), 2.87 NMR (101 MHz, D₂O) δ 165.9, 77.5, 72.8, 57.4, 52.6, 49.1, 43.3,

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2017

View Article Online

Paper

Organic & Biomolecular Chemistry

14.4. HRMS-ESI: m/z calcd for C₈H₁₅N₂O₃187.1083 [M + H⁺];

found: 187.1085.

2-((3S,7S,8S,8aS)-7,8-Dihydroxy-4-oxooctahydropyrrolo[1,2-a]-

pyrazin-3-yl)acetic acid (29s). The precursor (2S,3S,4S)-N-benzyl-

(3S,7S,8S,8aS)-7,8-Dihydroxy-3-isobutylhexahydropyrrolo[1,2-a]- oxycarbonyl-2-(((S)-aspartic(β^tBu)amidyl)methyl)-3,4-dihydroxy-

pyrazin-4(1H)-one (29p). The precursor (2S,3S,4S)-N-benzyloxy- pyrrolidine (27t) (64 mg, 47% yield) was purified by HPLC:

carbonyl-2-(((S)-leucineamidyl)methyl)-3,4-dihydroxypyrrolidine gradient elution 0% to 70% B during 40 min. HPLC analysis:

(27p) (45 mg, 50% yield) was purified by HPLC: gradient gradient elution from 10% to 70% B in 30 min; t_R= 20.6 min.

elution 0% to 70% B during 40 min. HPLC analysis: gradient ¹H NMR (400 MHz, CD₃OD) δ 7.36 (m, 5H, Ar), 5.19 (s, 2H,

1

elution from 10% to 70% B in 30 min; t_R= 18.5 min. H NMR OCH₂Ph), 4.19 (m, 1H, H-7), 4.09 (br s, 1H, H-4), 4.02 (br s, 2H

(400 MHz, D₂O) δ 7.47 (d, J = 13.8 Hz, 5H, Ar), 5.21 (m, 2H, H-2-H-3), 3.75 (dd, J = 11.6, 4.1 Hz, 1H, H-5), 3.47 (m, 3H, H-5′-

OCH₂Ph), 4.26 (m, 1H, H-4), 4.15 (m, 2H, H-2-H-3), 4.10 (br s, H-6-H-6′), 3.00 (t, J = 4.8 Hz, 2H, H-8-H-8′), 1.48 (s, 9H, CH₃).

1H, H-3-rotamer), 4.02 (m, 1H, H-7), 3.84 (m, 2H, H-5-H-7- ¹³C NMR (101 MHz, CD₃OD) δ 170.0 (2C-CONH₂-COO^tBu),

rotamer), 3.47 (m, 2H, H-5′-H-6), 3.32 (m, 1H, H-6′), 1.75 (m, 159.0 (COBn), 137.6 (C-Ar), 129.7 (C-Ar), 129.6 (C-Ar), 129.4

3H, H-8-H-8′-H-9), 1.55 (m, 2H, H-8-rotamer-H-9-rotamer), 0.94 (C-Ar), 129.2 (C-Ar), 129.1 (C-Ar), 84.1 (C-CH₃), 79.5 (C-3), 75.2

(m, 6H, CH₃). ¹³C NMR (101 MHz, D₂O) δ 171.08 (CONH₂), (C-4), 68.9 (OCH₂Ph), 64.4 (C-2), 58.4 (C-7), 54.4 (C-5), 51.8

158.19 (COBn), 156.45 (COBn-rotamer), 135.74 (C-Ar), 131.96 (C-6), 36.7 (C-8), 28.2 (3CH₃). The precursor (2S,3S,4S)-N-benzyl-

(C-Ar-rotamer), 129.03 (C-Ar), 128.95 (C-Ar), 128.74 (C-Ar), oxycarbonyl-2-(((S)-asparticamidyl)methyl)-3,4-dihydroxypyrro-

128.54 (C-Ar), 127.97 (C-Ar), 78.27 (C-3), 77.51 (C-3 rotamer), lidine (27s) (55 mg, 47% yield) was prepared by removing the

73.42 (C-4), 72.93 (C-4 rotamer), 68.53 (CH₂Ph), 68.18 (CH₂Ph tBu ester of the β-carboxylate group. Deprotection of the tBu

rotamer), 62.01 (C-2), 59.80 (C-7), 59.42 (C-7 rotamer), 53.07 group: 27t (60 mg, 0.13 mmol) was dissolved in trifluoroacetic

(C-5), 52.35 (C-5 rotamer), 48.92 (C-6), 48.26 (C-6 rotamer), acid (TFA) (7 mL) and left to stand at room temperature for

38.91 (C-8), 38.62 (C-8 rotamer), 23.96 (C-9), 21.92 (C-10), 21.86 6 h. After that time, no starting material was detected by

(C-10 rotamer), 21.12 (C-11), 20.92 (C-11 rotamer). The title HPLC. The derivative was purified by HPLC using a gradient

compound (20 mg, 99% yield) was prepared according to the elution: 0% to 70% B during 40 min. HPLC analysis: gradient

1

general procedure described above. [α]²_D²= −3.8 (c 0.9 in elution from 10% to 70% B in 30 min; t_R= 13.3 min. H NMR

MeOH). ¹H NMR (400 MHz, D₂O) δ 4.33 (dd, ³J(H,H) = 14.3, 7.2 (400 MHz, CD₃OD) δ 7.35 (m, 5H, Ar), 5.20 (m, 2H, OCH₂Ph),

Hz, 1H), 4.06 (dd, ³J(H,H) = 10.0, 3.5 Hz, 1H), 3.96 (t, ³J(H,H) = 4.21 (m, 1H, H-7), 4.09 (br s, 1H, H-4), 4.03 (br s, 2H, H-2-H-3),

7.5 Hz, 1H), 3.88 (m, 2H), 3.80 (dd, ³J(H,H) = 12.5, 7.8 Hz, 1H), 3.75 (dd, J = 11.7, 4.3 Hz, 1H, H-5), 3.56 (dd, J = 13.0, 2.6 Hz,

3

3.52 (dd, ³J(H,H) = 12.6, 6.8 Hz, 1H), 3.29 (t, J(H,H) = 11.6 Hz, 1H, H-6), 3.45 (m, 2H, H-5′-H-6′), 3.05 (dd, J = 9.2, 5.8 Hz, 2H,

3

1H), 1.96 (m, 1H), 1.79 (m, 2H), 0.98 (t, J(H,H) = 5.7 Hz, 6H). H-8-H-8′). ¹³C NMR (101 MHz, CD₃OD) δ 172.5 (CONH₂), 170.2

¹³C NMR (101 MHz, D₂O) δ 165.7, 77.4, 72.6, 57.1, 54.8, 49.2, (COOH), 158.9 (COBn), 137.6 (C-Ar), 129.6 (2C-Ar), 129.3

43.3, 38.6, 23.7, 22.1, 19.9. HRMS-ESI: m/z calcd for (C-Ar), 129.1 (2C-Ar), 79.6 (C-3), 75.3 (C-4), 68.9 (OCH₂Ph), 64.5

C₁₁H₂₁N₂O₃229.1552 [M + H⁺]; found: 229.1545.

(C-2), 58.5 (C-7), 54.5 (C-5), 51.6 (C-6), 35.5 (CONH₂). The title

(3S,7S,8S,8aS)-3-Benzyl-7,8-dihydroxyhexahydropyrrolo[1,2-a]- compound (32 mg, 99% yield) was then prepared according to

pyrazin-4(1H)-one (29q). The precursor (2S,3S,4S)-N-benzyloxy- the general procedure described above. [α]²_D²= +46.6 (c 0.8 in

carbonyl-2-(((S)-phenylalanineamidyl)methyl)-3,4-dihydroxy- MeOH). ¹H NMR (400 MHz, D₂O) δ 4.35 (dd, ³J(H,H) = 14.3, 7.1

3

pyrrolidine (27q) (54 mg, 55% yield) was purified by HPLC: Hz, 1H), 4.29 (m, 1H), 3.95 (m, 3H), 3.84 (dd, J(H,H) = 12.6,

3

gradient elution: 0% to 70% B during 40 min. HPLC analysis: 7.9 Hz, 1H), 3.48 (dd, J(H,H) = 12.6, 6.8 Hz, 1H), 3.39 (t, J(H,

3

gradient elution from 10% to 70% B in 30 min; t_R= 19.4 min. H) = 11.8 Hz, 1H), 3.23 (dd, J(H,H) = 18.4, 5.5 Hz, 1H), 3.07

¹H NMR (400 MHz, CD₃OD) δ 7.32 (m, 10H, Ar), 5.20 (m, 2H, (dd, ³J(H,H) = 18.4, 3.7 Hz, 1H). ¹³C NMR (101 MHz, D₂O) δ

OCH₂Ph), 4.23 (dd, J = 7.4, 6.1 Hz, 1H, H-7), 4.06 (br s, 1H, 173.8, 164.3, 77.4, 72.7, 57.2, 53.1, 49.1, 43.8, 33.6. HRMS-ESI:

H-4), 4.00 (m, 1H, H-2), 3.95 (s, 1H, H-3), 3.73 (dd, J = 11.7, 4.3 m/z calcd for C₉H₁₅N₂O₅231.0981 [M + H⁺]; found: 231.0995.

Hz, 1H, H-5), 3.40 (m, 3H, H-5′-H-6-H-6′), 3.21 (ddd, J = 21.5,

1-(3-((3S,7S,8S,8aS)-7,8-Dihydroxy-4-oxooctahydropyrrolo-

13.9, 6.8 Hz, 2H, CH₂Ph). ¹³C NMR (101 MHz, CD₃OD) δ 170.3 [1,2-a]pyrazin-3-yl)propyl)guanidine (29u). The precursor

(CONH₂), 159.1 (COBn), 137.6 (C-Ar), 135.0 (C-Ar), 130.6 (2S,3S,4S)-N-benzyloxycarbonyl-2-(((S)-arginineamidyl)methyl)-

(2C-Ar), 130.0 (2C-Ar), 129.6 (C-Ar), 129.3 (C-Ar), 129.2 (C-Ar), 3,4-dihydroxypyrrolidine (27u) (49 mg, 48% yield) was purified

128.9 (C-Ar), 79.4 (C-3), 75.3 (C-4), 68.9 (OCH₂Ph), 64.3 (C-2), by HPLC: gradient elution 0% to 60% B during 40 min. HPLC

62.8 (C-7), 54.5 (C-5), 50.7 (C-6), 37.8 (C-8). The title compound analysis: gradient elution from 10% to 70% B in 30 min; t_R

=

1

(34 mg, 99% yield) was prepared according to the general pro- 12.2 min. H NMR (400 MHz, CD₃OD) δ 7.36 (m, 5H, Ar), 5.15

1

cedure described above. [α]²_D²= −5.7 (c 1.1 in MeOH). H NMR (m, 2H, OCH₂Ph), 4.10 (d, J = 3.6 Hz, 1H, H-4), 4.03 (br s, 3H,

(400 MHz, D₂O) δ 7.42 (m, 5H), 4.34 (m, 2H), 3.95 (m, 1H), H-2-H-3-H-7), 3.75 (dd, J = 11.7, 4.3 Hz, 1H, H-5), 3.49 (m, 2H,

3.84 (m, 3H), 3.61 (dd, ³J(H,H) = 14.8, 4.2 Hz, 1H), 3.56 (dd, H-5′-H-6), 3.35 (m, 1H, H-6′), 3.23 (t, J = 5.8 Hz, 2H, H-10-

³J(H,H) = 12.7, 6.9 Hz, 1H), 3.26 (t, ³J(H,H) = 12.1 Hz, 1H), 3.14 H-10′), 1.98 (m, 2H, H-8-H-8′), 1.66 (m, 2H, H-9-H-9′). ¹³C NMR

(dd, ³J(H,H) = 14.9, 10.1 Hz, 1H). ¹³C NMR (101 MHz, D₂O) (101 MHz, CD₃OD) δ 170.7 (CONH₂), 159.2 (COBn), 158.7

δ 164.2, 133.9, 129.3, 129.2, 128.1, 77.4, 72.7, 58.0, 57.1, 49.2, (CvNH), 137.6 (C-Ar), 129.7 (C-Ar), 129.6 (C-Ar), 129.4 (C-Ar),

43.5, 35.0. HRMS-ESI: m/z calcd for C₁₄H₁₉N₂O₃263.1396 129.2 (C-Ar), 129.0 (C-Ar), 79.4 (C-3), 75.3 (C-4), 68.9 (OCH₂Ph),

[M + H⁺]; found: 263.1399.

64.4 (C-2), 61.1 (C-7), 54.5 (C-5), 50.9 (C-6), 41.7 (C-10), 28.8

2018 | Org. Biomol. Chem., 2013, 11, 2005–2021

View Article Online

Organic & Biomolecular Chemistry

Paper

(C-8), 25.0 (C-9). The title compound (60 mg, 99% yield) was

prepared according to the general procedure described above.

R. J. Molyneux and N. Asano, J. Nat. Prod., 2002, 65,

198–202.

3 J. P. Saludes, S. C. Lievens and T. F. Molinski, J. Nat. Prod.,

2007, 70, 436–438.

4 N. Asano, R. J. Nash, R. J. Molyneux and G. W. J. Fleet,

Tetrahedron: Asymmetry, 2000, 11, 1645–1680.

5 G. W. J. Fleet and P. W. Smith, Tetrahedron, 1986, 42,

5685–5692.

1

[α]²_D²= +16.9 (c 1.2 in MeOH). H NMR (400 MHz, D₂O) δ 4.33

(dd, ³J(H,H) = 14.4, 7.1 Hz, 1H), 4.00 (dd, ³J(H,H) = 8.3, 4.4 Hz,

3

1H), 3.96 (m, 1H), 3.88 (m, 2H), 3.81 (dd, J(H,H) = 12.6, 7.8

Hz, 1H), 3.52 (dd, ³J(H,H) = 12.6, 6.9 Hz, 1H), 3.26 (m, 3H),

3

2.18 (ddd, J(H,H) = 15.6, 10.2, 4.8 Hz, 1H), 1.91 (m, 1H), 1.77

(m, 2H). ¹³C NMR (101 MHz, D₂O) δ 166.8, 156.7, 77.5, 72.7,

58.4, 56.3, 49.1, 43.7, 40.3, 27.2, 24.2. HRMS-ESI: m/z calcd for

C₁₁H₂₂N₅O₃272.1723 [M + H⁺]; found: 272.1716.

6 N. Asano, K. Ikeda, L. Yu, A. Kato, K. Takebayashi,

I. Adachi, I. Kato, H. Ouchi, H. Takahata and G. W. J. Fleet,

Tetrahedron: Asymmetry, 2005, 16, 223–229.

7 X. Garrabou, L. Gomez, J. Joglar, S. Gil, T. Parella, J. Bujons

and P. Clapés, Chem.–Eur. J., 2010, 16, 10691–10706.

8 A. M. Scofield, L. E. Fellows, R. J. Nash and G. W. J. Fleet,

Life Sci., 1986, 39, 645–650.

9 B. Andersen, A. Rassov, N. Westergaard and K. Lundgren,

Biochem. J., 1999, 342, 545–550; K. Fosgerau,

N. Westergaard, B. Quistorﬀ, N. Grunnet, M. Kristiansen

and K. Lundgren, Arch. Biochem. Biophys., 2000, 380,

274–284; N. G. Oikonomakos, C. Tiraidis, D. D. Leonidas,

S. E. Zographos, M. Kristiansen, C. U. Jessen, L. Norskov-

Lauritsen and L. Agius, J. Med. Chem., 2006, 49, 5687–5701;

A. B. Walls, H. M. Sickmann, A. Brown, S. D. Bouman,

B. Ransom, A. Schousboe and H. S. Waagepetersen,

J. Neurochem., 2008, 10, 1–9; Y. Minami, C. Kuriyama,

K. Ikeda, A. Kato, K. Takebayashi, I. Adachi, G. W. J. Fleet,

A. Kettawan, T. Okamoto and N. Asano, Bioorg. Med. Chem.,

2008, 16, 2734–2740.

(2S,3S,4S)-N-Benzyloxycarbonyl-2-(((S)-valineamidyl)methyl)-

3,4-dihydroxypyrrolidine (27o). The title compound (60 mg,

50% yield) was prepared according to the general procedure

described above and purified by HPLC: gradient elution 0% to

70% B during 40 min. HPLC analysis: gradient elution from

1

10% to 70% B in 30 min; t_R= 16.4 min. H NMR (400 MHz,

CD₃OD) δ 7.37 (m, 5H, Ar), 5.18 (m, 2H, OCH₂Ph), 4.08 (br s,

1H, H-4), 4.05 (d, J = 7.0 Hz, 1H, H-2), 4.00 (br s, 1H, H-3), 3.83

(d, J = 4.5 Hz, 1H, H-7), 3.75 (dd, J = 11.7, 4.3 Hz, 1H, H-5),

3.48 (d, J = 11.8 Hz, 1H, H-5′), 3.43 (d, J = 2.2 Hz, 1H, H-6), 3.35

(m, 1H, H-6′), 2.26 (m, 1H, H-8), 1.10 (m, 6H, 2CH₃). ¹³C NMR

(101 MHz, CD₃OD) δ 169.7 (CONH₂), 159.3 (COBn), 137.6

(C-Ar), 129.6 (2C-Ar), 129.3 (C-Ar), 129.1 (2C-Ar), 79.5 (C-3),

75.3 (C-4), 69.0 (OCH₂Ph), 66.8 (C-7), 64.4 (C-2), 54.5 (C-5), 51.4

(C-6), 31.1 (C-8), 18.8 (CH₃), 17.8 (CH₃). This compound could

not be converted to the corresponding bicyclic (3S,7S,8S,8aS)-

7,8-dihydroxy-3-isopropylhexahydropyrrolo[1,2-a]pyrazin-4(1H)-

one. No further characterization was conducted.

10 M. Kimura, F.-j. Chen, N. Nakashima, I. Kimura, N. Asano

and S. Koya, J. Tradit. Med., 1995, 12, 214–219.

Inhibitory activity assays

11 J. Churruca, L. Vigil, E. Luna, J. Ruiz-Galiana and

M. Varela, Diabetes Metab. Syndr. Obes., 2008, 1, 3–11;

F. Donatelli, P. Cavagna, G. Di Dedda, A. Catenacci, M. Di

Nicola, L. Lorini, R. Fumagalli and F. Carli, Acta Anaesthe-

siol. Scand., 2008, 52, 1103–1110; A. Esteghamati,

O. Khalilzadeh, M. Anvari, M. S. Ahadi, M. Abbasi and

A. Rashidi, Arch. Med. Res., 2008, 39, 803–808.

Enzymatic inhibition assays on commercial glycosidases, the

kinetics of the inhibition, preparation of gut mucosal suspen-

sions, inhibition assays on rat intestinal disaccharidases and

MIC determination against the H37Rv Pasteur Mycobacterium

tuberculosis strain using the REMA plate method were per-

formed as described in previous work.^7,24The experimental

details are given in the ESI.†

12 R. R. Holman, C. A. Cull and R. C. Turner, Diabetes Care,

1999, 22, 960–964.

13 A. Ceriello, Diabetes Vasc. Dis. Res., 2008, 5, 260–268;

M. Cho, J. H. Han and S. You, LWT–Food Sci. Technol.,

2011, 44, 1164–1171; J. Singh, A. Dartois and L. Kaur,

Trends Food Sci. Technol., 2010, 21, 168–180.

14 L. Gómez, E. Molinar-Toribio, M. Á. Calvo-Torras,

C. Adelantado, M. E. Juan, J. M. Planas, X. Cañas,

C. Lozano, S. Pumarola, P. Clapés and J. L. Torres,

Br. J. Nutr., 2012, 107, 1739–1746.

Acknowledgements

This work was supported by the Spanish MICINN CTQ2009-

07359 and CTQ2009-08328, Generalitat de Catalunya (2009

SGR 00281) and ERA-IB MICINN. PIM2010EEI-00607 (EIB.

10.012.MicroTechEnz). L. Gomez acknowledges Generalitat de

Catalunya and Bioglane S.L.N.E. for the predoctoral contract.

15 D. Best, S. F. Jenkinson, A. W. Saville, D. S. Alonzi,

M. R. Wormald, T. D. Butters, C. Norez, F. Becq, Y. Bleriot,

I. Adachi, A. Kato and G. W. J. Fleet, Tetrahedron Lett., 2010,

51, 4170–4174.

References

1 In this work the derivatives were named pyrrolidine deriva-

tives using the heterocyclic nomenclature rather than the 16 J. S. S. Rountree, T. D. Butters, M. R. Wormald, R. A. Dwek,

sugar nomenclature.

N. Asano, K. Ikeda, E. L. Evinson, R. J. Nash and

G. W. J. Fleet, Tetrahedron Lett., 2007, 48, 4287–4291;

J. S. S. Rountree, T. D. Butters, M. R. Wormald,

S. D. Boomkamp, R. A. Dwek, N. Asano, K. Ikeda,

2 D. W. C. Jones, R. J. Nash, E. A. Bell and J. M. Williams,

Tetrahedron Lett., 1985, 26, 3125–3126; K. Yasuda, H. Kizu,

T. Yamashita, Y. Kameda, A. Kato, R. J. Nash, G. W. J. Fleet,

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2019

View Article Online

Paper

E. L. Evinson, R. J. Nash and G. W. J. Fleet, ChemMedChem,

Organic & Biomolecular Chemistry

Asymmetry, 1990, 1, 119–136; Y. J. Kim, M. Kido, M. Bando

and T. Kitahara, Tetrahedron, 1997, 53, 7501–7508; X. Zhou,

W.-J. Liu, J.-L. Ye and P.-Q. Huang, Tetrahedron, 2007, 63,

6346–6357; Y.-F. Chang, C.-W. Guo, T.-H. Chan, Y.-W. Pan,

E.-L. Tsou and W.-C. Cheng, Mol. Diversity, 2011, 15,

203–214; P. K. Upadhyay and P. Kumar, Synthesis, 2010,

3063–3066; G.-N. Wang, L. Yang, L.-H. Zhang and X.-S. Ye,

J. Org. Chem., 2011, 76, 2001–2009.

2009, 4, 378–392.

17 F. Popowycz, S. Gerber-Lemaire, R. Demange, E. Rodriguez-

Garcia, A. T. C. Asenjo, I. Robina and P. Vogel, Bioorg. Med.

Chem. Lett., 2001, 11, 2489–2493; A. T. Carmona,

F. Popowycz, S. Gerber-Lemaire, E. Rodriguez-Garcia,

C. Schutz, P. Vogel and I. Robina, Bioorg. Med. Chem., 2003,

11, 4897–4911; H. Fiaux, D. A. Kuntz, D. Hoﬀman,

R. C. Janzer, S. Gerber-Lemaire, D. R. Rose and L. Juillerat- 32 L. Espelt, T. Parella, J. Bujons, C. Solans, J. Joglar,

Jeanneret, Bioorg. Med. Chem., 2008, 16, 7337–7346.

18 F. Popowycz, S. Gerber-Lemaire, E. Rodriguez-García,

C. Schütz and P. Vogel, Helv. Chim. Acta, 2003, 86,

1914–1948; F. Popowycz, S. Gerber-Lemaire, C. Schutz and

P. Vogel, Helv. Chim. Acta, 2004, 87, 800–810.

A. Delgado and P. Clapés, Chem.–Eur. J., 2003, 9,

4887–4899; L. Espelt, J. Bujons, T. Parella, J. Calveras,

J. Joglar, A. Delgado and P. Clapés, Chem.–Eur. J., 2005, 11,

1392–1401; X. Garrabou, J. A. Castillo, C. Guérard-Hélaine,

T. Parella, J. Joglar, M. Lemaire and P. Clapés, Angew.

Chem., Int. Ed., 2009, 48, 5521–5525.

19 H. Fiaux, F. Popowycz, S. Favre, C. Schutz, P. Vogel,

S. Gerber-Lemaire and L. Juillerat-Jeanneret, J. Med. Chem., 33 A. L. Concia, C. Lozano, J. A. Castillo, T. Parella, J. Joglar

2005, 48, 4237–4246. and P. Clapés, Chem.–Eur. J., 2009, 15, 3808–3816.

20 N. Asano, K. Oseki, H. Kizu and K. Matsui, J. Med. Chem., 34 M. A. Casadei, C. Galli and L. Mandolini, J. Am. Chem. Soc.,

1994, 37, 3701–3706; A. E. Stutz, Iminosugars as Glycosidase 1984, 106, 1051–1056.

Inhibitors: Nojirimycin and Beyond, Wiley-VCH, Weinheim, 35 H. J. Jeong, J. M. Lee, M. K. Kim and S.-G. Lee, J. Heterocycl.

1999. Chem., 2002, 39, 1019–1024.

21 S. Ishida, M. Okasaka, F. Ramos, Y. Kashiwada, Y. Takaishi, 36 G. M. Raghavendra, A. B. Ramesha, C. N. Revanna,

O. Kodzhimatov and O. Ashurmetov, J. Nat. Med., 2008, 62,

236–238.

22 M. Shibano, D. Tsukamoto, A. Masuda, Y. Tanaka and

G. Kusano, Chem. Pharm. Bull., 2001, 49, 1362–1365;

K. N. Nandeesh, K. Mantelingu and K. S. Rangappa, Tetra-

hedron Lett., 2011, 52, 5571–5574; M. Chakrabarty,

R. Mukherjee, S. Karmakar and Y. Harigaya, Monatsh.

Chem., 2007, 138, 1279–1282.

M. Shibano, D. Tsukamoto and G. Kusano, Heterocycles, 37 A. Kumar, M. A. Alam, S. Rani and Y. D. Vankar, Carbohydr.

2002, 57, 1539–1553.

Res., 2010, 345, 1142–1148; B. Chandrasekhar, A. Madhan

and B. V. Rao, Tetrahedron, 2007, 63, 8746–8751;

A. E. Hakansson, J. van Ameijde, L. Gughelmini, G. Horne,

R. J. Nash, E. L. Evinson, A. Kato and G. W. J. Fleet, Tetra-

hedron: Asymmetry, 2007, 18, 282–289; U. M. Lindstrom,

R. Ding and O. Hidestal, Chem. Commun., 2005, 1773–1774;

D.-P. Pham-Huu, Y. Gizaw, J. N. BeMiller and L. Petruš,

Tetrahedron, 2003, 59, 9413–9417; A. T. Carmona,

J. Fuentes, I. Robina, E. Rodriguez Garcia, R. Demange,

P. Vogel and A. L. Winters, J. Org. Chem., 2003, 68,

3874–3883; I. Navarro and P. Vogel, Helv. Chim. Acta, 2002,

85, 152–160; R. E. Lee, M. D. Smith, R. J. Nash,

R. C. Griﬃths, M. McNeil, R. K. Grewal, W. Yan,

G. S. Besra, P. J. Brennan and G. W. J. Fleet, Tetrahedron

Lett., 1997, 38, 6733–6736.

23 E.-L. Tsou, S.-Y. Chen, M.-H. Yang, S.-C. Wang,

T.-R.R. Cheng and W.-C. Cheng, Bioorg. Med. Chem., 2008,

16, 10198–10204.

24 L. Gómez, X. Garrabou, J. Joglar, J. Bujons, T. Parella,

C. Vilaplana, P. J. Cardona and P. Clapés, Org. Biomol.

Chem., 2012, 10, 6309–6321.

25 D. A. Horton, G. T. Bourne and M. L. Smythe, Chem. Rev.,

2003, 103, 893–930.

26 C. De Risi, M. Pelà, G. P. Pollini, C. Trapella and

V. Zanirato, Tetrahedron: Asymmetry, 2010, 21, 255–274.

27 B. E. Maryanoﬀ and M. J. Costanzo, Bioorg. Med. Chem.,

2008, 16, 1562–1595.

28 R. Lucas, P. Balbuena, J. C. Errey, M. A. Squire,

S. S. Gurcha, M. McNeil, G. S. Besra and B. G. Davis, Chem-

BioChem, 2008, 9, 2197–2199; J. P. Shilvock, J. R. Wheatley, 38 G. A. R. Y. Suaifan, M. F. Mahon, T. Arafat and

R. J. Nash, A. A. Watson, R. C. Griﬃths, T. D. Butters,

M. Muller, D. J. Watkin, D. A. Winkler and G. W. J. Fleet,

J. Chem. Soc., Perkin Trans. 1, 1999, 2735–2745;

J. A. Maddry, N. Bansal, L. E. Bermudez, R. N. Comber,

M. D. Threadgill, Tetrahedron, 2006, 62, 11245–11266;

B. F. Gisin and R. B. Merrifield, J. Am. Chem. Soc., 1972, 94,

3102–3106; E. Pedroso, A. Grandas, X. de las Heras,

R. Eritja and E. Giralt, Tetrahedron Lett., 1986, 27, 743–746.

I. M. Orme, W. J. Suling, L. N. Wilson and R. C. Reynolds, 39 A. M. Abdula, R. A. Khalaf, M. S. Mubarak and M. O. Taha,

Bioorg. Med. Chem. Lett., 1998, 8, 237–242.

29 M. Gutierrez, T. Parella, J. Joglar, J. Bujons and P. Clapés,

Chem. Commun., 2011, 47, 5762–5764.

J. Comput. Chem., 2011, 32, 463–482; G. Dickson Lucas,

E. Leroy and J.-L. Reymond, Org. Biomol. Chem., 2004, 2,

1217–1226.

30 X. Garrabou, J. Calveras, J. Joglar, T. Parella, J. Bujons and 40 T. M. Chapman, S. Courtney, P. Hay and B. G. Davis,

P. Clapes, Org. Biomol. Chem., 2011, 9, 8430–8436. Chem.–Eur. J., 2003, 9, 3397–3414.

31 G. W. J. Fleet, S. J. Nicholas, P. W. Smith, S. V. Evans, 41 J. H. Kim, M. J. Curtis-Long, W. D. Seo, J. H. Lee, B. W. Lee,

L. E. Fellows and R. J. Nash, Tetrahedron Lett., 1985, 26,

3127–3130; G. W. J. Fleet and D. R. Witty, Tetrahedron:

Y. J. Yoon, K. Y. Kang and K. H. Park, Bioorg. Med. Chem.

Lett., 2005, 15, 4282–4285.

2020 | Org. Biomol. Chem., 2013, 11, 2005–2021

View Article Online

Organic & Biomolecular Chemistry

Paper

42 S. P. Kawatkar, D. A. Kuntz, R. J. Woods, D. R. Rose and

G. J. Boons, J. Am. Chem. Soc., 2006, 128, 8310–8319;

D. A. Kuntz, W. Z. J. Guo, D. R. Rose and G.-J. Boons, Chem-

Commun., 2005, 4949–4951; C. Chevrier, D. LeNouen,

M. Neuburger, A. Defoin and C. Tarnus, Tetrahedron Lett.,

2004, 45, 5363–5366.

BioChem, 2009, 10, 268–277; D. A. Kuntz, C. A. Tarling, 45 N. Asano, K. Yasuda, H. Kizu, A. Kato, J.-Q. Fan, R. J. Nash,

S. G. Withers and D. R. Rose, Biochemistry, 2008, 47,

10058–10068; W. Zhong, D. A. Kuntz, B. Ember, H. Singh,

G. W. J. Fleet and R. J. Molyneux, Eur. J. Biochem., 2001,

268, 35–41.

K. W. Moremen, D. R. Rose and G. J. Boons, J. Am. Chem. 46 Evaluation of Enzyme Inhibitors in Drug Discovery: A Guide to

Soc., 2008, 130, 8975–8983; S. Howard, S. He and

S. G. Withers, J. Biol. Chem., 1998, 273, 2067–2072;

Medicinal Chemists and Pharmacologists, ed. R. A. Copeland,

John Wiley & Sons, Hoboken, NJ, USA, 2005.

V. R. Doddi and Y. D. Vankar, Eur. J. Org. Chem., 2007, 47 J.-C. Palomino, A. Martin, M. Camacho, H. Guerra,

5583–5589.

J. Swings and F. Portaels, Antimicrob. Agents Chemother.,

2002, 46, 2720–2722.

43 J. Calveras, M. Egido-Gabás, L. Gómez, J. Casas, T. Parella,

J. Joglar, J. Bujons and P. Clapés, Chem.–Eur. J., 2009, 15, 48 H. Kayakiri, K. Nakamura, S. Takase, H. Setoi, I. Uchida,

7310–7328.

H. Terano, M. Hashimoto, T. Tada and S. Koda, Chem.

Pharm. Bull., 1991, 39, 2807–2812.

44 E. Moreno-Clavijo, A. T. Carmona, Y. Vera-Ayoso,

A. J. Moreno-Vargas, C. Bello, P. Vogel and I. Robina, Org. 49 A. Lei, G. Liu and X. Lu, J. Org. Chem., 2002, 67, 974–980.

Biomol. Chem., 2009, 7, 1192–1202; A. J. Moreno-Vargas, 50 Y. Huang, D. R. Dalton and P. J. Carroll, J. Org. Chem.,

A. T. Carmona, F. Mora, P. Vogel and I. Robina, Chem.

1997, 62, 372–376.

Org. Biomol. Chem., 2013, 11, 2005–2021 | 2021

Article Doi

Chemo-enzymatic synthesis and glycosidase inhibitory properties of DAB and LAB derivatives

DOI: 10.1039/c3ob27343a

Source and publish data:

Authors:

Article abstract of DOI:10.1039/c3ob27343a

Full text of DOI:10.1039/c3ob27343a

Products guided by the article

R&D Labs maybe for 1427173-61-2

Relevant to this article

Hot Product