The 2α-(3-hydroxypropyl) group as an active motif in vitamin D3 analogues as agonists of the mutant vitamin D receptor (Arg274Leu)

Available online at www.sciencedirect.com

Bioorganic & Medicinal Chemistry 16 (2008) 3002–3024

The 2a-(3-hydroxypropyl) group as an active motif

in vitamin D₃analogues as agonists of the mutant

vitamin D receptor (Arg274Leu)

Shinobu Honzawa,^a,ꢀYasuhiro Yamamoto,^aAtsushi Yamashita,^bTakayuki Sugiura,^b

Masaaki Kurihara,^cMidori A. Arai,^aShigeaki Kato^dand Atsushi Kittaka^a,*

^aDepartment of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa 229-0195, Japan

^bDepartment of Hygienic Chemistry and Nutrition, Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa 229-0195, Japan

^cNational Institute of Health Sciences, Tokyo 158-8501, Japan

^dInstitute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan

Received 19 November 2007; revised 18 December 2007; accepted 19 December 2007

Available online 14 January 2008

Abstract—We designed and synthesized 1a- and 1b-hydroxymethyl-2a-(3-hydroxypropyl)-25-hydroxyvitamin D₃(2a,b) and related

analogues 2a-(3-hydroxypropyl)-25-hydroxyvitamin D₃(3), Posner’s analogues of 1a- and 1b-hydroxymethyl-25-hydroxyvitamin

D₃(4a,b), as well as 2a-(3-hydroxypropyl)-1a,25-dihydroxyvitamin D₃(5), to conﬁrm the eﬀect of the 1a-hydroxy group

and/or 2a-(3-hydroxypropyl) group of vitamin D₃analogues with the modiﬁed A-ring moiety on the mutant vitamin D receptor,

VDR(Arg274Leu). The 2a-(3-hydroxypropyl) group showed better eﬀect on enhancement of the transcriptional activity through

the mutant VDR than the 1a- and 1b-hydroxymethyl groups.

1. Introduction

extracellular stimuli in a ligand-dependent fashion. X-

ray crystal structure analysis³shows that 1 is anchored

in the ligand binding domain (LBD) of the VDR

through hydrogen bonds between hydrophilic amino

acid residues and three hydroxy groups of 1, that is,

1a-OH, 3b-OH, and 25-OH (Fig. 1). It seems reasonable

that the substitution of one or more of these amino acids

would reduce the aﬃnity of 1 for the VDR. A rare genet-

ic disease called hereditary vitamin D resistant rickets

(HVDRR) has been clinically recognized to occur result-

ing from mutations of VDR.⁴Mutations appear in every

part of the receptor, and two mutations that relate to

hydrogen bond formation are known so far (His305Gln

and Arg274Leu), the latter showing severe rickets.

Arg274 forms hydrogen bond with 1a-OH (Fig. 1),

and its substitution with hydrophobic Leu leads to det-

rimental loss of the aﬃnity for 1 (ca. 1/1000 against the

wild type receptor).⁵To overcome the low activity of 1

in the mutant receptor, two research groups have re-

ported vitamin D analogues designed for the mutant

receptor. Koh et al. reported 1a-O-benzylated analogues

in which O-benzyl groups were expected to compensate

for the loss of aﬃnity by new hydrophobic interactions

through the benzyl group and the resulting hydrophobic

pocket of the mutant receptor.⁶Posner and co-workers

1a,25-Dihydroxyvitamin D₃(1a,25(OH)₂D₃, 1) has

drawn the attention of many researchers in academia

and industry, because of its wide variety of biological

and pharmacological activities.¹It is well known that

1 regulates calcium and phosphate homeostasis together

with parathyroid hormone (PTH) and calcitonin, and its

deﬁciency causes osteomalacia or rickets. 1a,25(OH)₂D₃

has also been shown to inﬂuence cell diﬀerentiation and

growth, and 1 and its analogues have been investigated

as drugs for diseases such as cancer, psoriasis, immuno-

deﬁciency, and so on. Many of the functions of 1 are

mediated through binding to a speciﬁc nuclear receptor,

the vitamin D receptor (VDR), which is a member of

steroid-thyroid hormone receptor superfamily.²These

receptors act as transcription factors, which activate or

suppress gene transcription in response to intra- or

Keywords: Vitamin D analogues; Vitamin D receptor; Mutant vitamin

D receptor; Structure–function relationships.

*

ꢀ

Corresponding author. E-mail: akittaka@pharm.teikyo-u.ac.jp

Present address: Faculty of Pharmaceutical Sciences, Niigata

University of Pharmacy and Applied Life Sciences (NUPALS),

Niigata 956-8603, Japan.

doi:10.1016/j.bmc.2007.12.039

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3003

Hydrogen bond

25

His-305

OH

H

His-397

H

Ser-278

3 1

Ser-237

HO

OH

1

Tyr-143

Arg-274

Figure 1. Crystal structure of VDR bound to 1a,25(OH)₂D₃(1) by D. Moras and co-workers³.

showed that 1-hydroxymethylated analogue has im-

proved the vitamin D action by the mutant receptor,⁷

but this restoration eﬀect was brought about by double

modiﬁcation, because the side chain was also changed.

In order to conﬁrm the eﬀect of the 1a-hydroxymethyl

group on the mutant receptor, and to increase the activ-

ities of the analogues further, we designed analogues

that have 2a-(3-hydroxypropyl) group, a functional

group has been found in our laboratory to potentiate

the vitamin D action,^8,9with or without a 1a-hydroxy-

methyl group (Fig. 2). Our group has already reported

that 2a-(3-hydroxypropyl)-1a,25(OH)₂D₃(5) could act

as a ligand for a mutant VDR(Arg274Ala), which was

an artiﬁcial mutant related to the mutant VDR

(Arg274Leu).¹⁰In the LBD of the VDR, there is a water

channel connecting the A-ring part of the LBD to the

surface of the VDR and forming a network of hydrogen

bonds.³The 2a-substituent aﬀects the presence and/or

the location of the water molecules in the channel, and

X-ray crystal structure demonstrated that the terminal

hydroxy group of 5 acts as one of the water molecules

to form hydrogen bonds with Arg274 and the other

water molecule located in the ligand binding pocket

(LBP) to organize the network and to enhance the bind-

ing aﬃnity for the VDR.¹¹

of CD-ring precursor bromooleﬁn 6 and A-ring syn-

thon enynes reported by Trost et al.¹²The CD-ring

precursor 6 could be prepared from vitamin D₃,¹²

and A-ring enynes were synthesized from D-glucose.

Our synthetic procedure reported recently¹³was mod-

iﬁed in order to introduce hydroxymethyl group into

the 1-position of vitamin D₃framework. As shown

in Scheme 2, the known sugar epoxide 7¹⁴reacted

with allylmagnesium chloride in THF to give allyl

substituted compound in good yield. The resulting sec-

ondary hydroxy group was silylated, and then the ter-

minal alkene was hydroborated, and oxidative workup

furnished primary alcohol, which was protected as

pivalate to give 8. Stereoselective reductive ring open-

ing reaction of benzylidene acetal was carried out by

using TFA–Et₃SiH in the presence of molecular sieves

3A.¹⁵Secondary alcohol 9 was oxidized by TPAP-

NMO, and then Lombardo methylenation¹⁶proceeded

in good yield to give 10. Hydroboration of exo-meth-

ylene group was carried out with BH₃ÆTHF, and then

oxidative workup gave a diastereomeric mixture of

primary alcohols (ratio 1.3:1), which could be sepa-

rated at this stage by silica gel ﬂash column chroma-

tography. Each isomer was transformed in the

following scheme in diastereomerically pure form.

The primary hydroxy group was protected as the piv-

alate (11a,b), and benzyl ether was converted to the

mesylate (12a,b), which was subjected to a nucleo-

philic bromination reaction. Reductive ring opening

of the bromo ether (13a,b) gave the primary alcohol

(14a,b), which upon treatment with TsCl followed by

TBAF furnished the epoxide (15a,b) in good yield.

Addition of lithium acetylide to the epoxide and meth-

anolysis of the pivalate gave the triol, which was pro-

2. Results and discussions

2.1. Synthesis

Retrosynthetic analysis of the vitamin D derivatives,

2a,b and 4a,b, is shown in Scheme 1. The strategy

was to use the palladium-catalyzed coupling reaction

OH

H

OH

H

OH

H

OH

H

3

1

2

HO

CH₂OH

HO

CH₂OH

HO

OH

HO

25(OH)D₃

OH

β

2a: 1 -CH₂OH

CH₂OH

4a

β

CH₂OH

: 1 -CH₂OH

3

5

2b

α

: 1 -CH₂OH

4b

α

: 1 -CH₂OH

Figure 2. Structures of vitamin D₃analogues tested.

3004

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

OH

H

OH

H

Vitamin D₃

H

6

Br

MeO

SiO

O

MeO

SiO

O

OH

OR"

OR

OR"

HO

Pd-catalyzed

coupling reaction SiO

OSi

R'

R' = H or CH₂CH₂CH₂OH

Hydroboration

MeO

O

MeO

SiO

O

D

-Glucose

O

Ph

OH

O

R'

7

Scheme 1. Retrosynthetic analysis of 1-hydroxymethylated analogues.

1) allylMgCl

2) TBSCl

MeO

O

MeO

O

7

MeO

O

9

O

TFA-Et₃SiH-MS3A

O

OBn

OH

OPiv

TBSO

Ph

O

Ph

TBSO

3) BH₃THF

4) H₂O₂,NaOH

5) PivCl

O

OPiv

8

72% (5 steps)

59%

MeO

O

MeO

TBSO

O

OBn

OPiv

OBn

OPiv

1) TPAP, NMO

2) Zn-CH₂Br₂-TiCl₄

1) H₂, Pd(OH)₂/C

2) MsCl, Et₃N

1) BH₃•THF

TBSO

2) NaOH, H₂O₂

3) PivCl

OPiv

10

11a (Less polar isomer) 43% (3 steps)

11b (More polar isomer) 33% (3 steps)

62% (2 steps)

MeO

O

MeO

O

HO

OMs

OPiv

Br

OPiv

Zn, NaBH₃CN

LiBr,TMU

OPiv

TBSO

OPiv

13a 91%

12a quant. (2 steps)

12b 86% (2 steps)

14a 88%

14b

13b

78%

quant.

1)

Li

TMS

1) TsCl

BF₃OEt₂

O

OTBS

OPiv

TBSO

2) TBAF

2) NaOMe, MeOH

3) TBSOTf, 2,6-lutidine

OTBS

16a

16b

38% (3 steps)

58% (3 steps)

15a

15b

87% (2 steps)

OH

H

1)

H

Br

6

H

Pd(PPh₃)₄, PhMe-Et₃N

2) HF-Py

OH

HO

2a

2b

38% (2 steps)

53% (2 steps)

Scheme 2. Synthesis of 1a- and 1b-hydroxymethyl-2a-(3-hydroxypropyl)-25-hydroxyvitamin D₃analogues 2a and 2b.

tected as the TBS ether (16a,b). Trost coupling reac-

tion of the A-ring enyne (16a,b) and the CD-ring

bromooleﬁn 6, followed by deprotection of the TBS

groups, gave the desired analogues (Scheme 2).

The stereochemistry at the 1-position could be deter-

mined by 2D NMR (HH-COSY) and NOE experiments

for 2b that was derived from 11b (more polar isomer).

NOE enhancement was observed between 3-H and meth-

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3005

OH

H

6.5%

H

OH

2a

11a

)

H

(from less polar isomer

α

β)

(1 ,3

Desired

3

HO

1

2

OH

Configuration

1

HO

β

β)

(1 ,3

2

H

Undesired Configuration

OH

2b

irr.

11b

(From more polar isomer

)

Figure 3. NOE experiments for 2b.

1) allylMgCl

MeO

O

MeO

O

7

MeO

O

1) Li, liq. NH₃

2) TrCl, Py

OTr

OH

OTBDPS

2) BH₃THF

3) H₂O₂, NaOH

4) TBDPSCl

5) TBSOTf

TBSO

O

Ph

O

Ph

TBSO

18

O

OTBDPS

17

52% (5 steps)

88% (2 steps)

1) NaH, CS₂,

and then MeI

MeO

O

MeO

TBSO

19

O

Br

OTr

1) Et₂AlCl

Zn, NaBH₃CN

TBSO

20

2) n-Bu₃SnH, AIBN

2) MsCl, Py

3) LiBr

OTBDPS

84% (3 steps)

93% (3 steps)

HO

TBSO

1) Li

BF₃OEt₂

TMS

1) TsCl, Py

2) TBAF

O

TBSO

2) K₂CO₃, MeOH

3) TBSOTf

3) TBSCl

OTBDPS

OTBS

58% (3 steps)

OTBS

23

59% (3 steps)

22

21

81%

OH

H

OH

H

1)

_H6

Br

H

Pd(PPh₃)₄

2) TBAF

3

HO

35%

OH

Scheme 3. Synthesis of 1-unsubstituted analogue 3.

ylene protons (or one of the methylene protons) of the

hydroxymethyl group at the 1-position, so this isomer

must have the 1a,2a,3b-conﬁguration and, accordingly,

the other isomer must have 1b,2a,3b-stereochemistry

(Fig. 3).

stantially by the same manner, except that epoxide ring

opening of 7 was carried out with LiAlH₄¹⁷(Scheme 4).

At the stage of hydroboration of 26, the diastereoselec-

tivity was relatively high (ca. 8.4:1) in contrast with the

2a-(3-hydroxypropyl) series. The conﬁguration of the

major diastereoisomer could be inverted via oxidation,

epimerization, and reduction. Stereochemisty of 4a

and 4b was similarly determined by NMR experiments

(Fig. 4).

As a reference compound, 2a-(3-hydroxypropyl)-25-

hydroxyvitamin D₃(3), which does not have a 1a-OH

group but does have a 2a-(3-hydroxypropyl) group,

could also be prepared by the similar procedure as

shown in Scheme 3. Deoxygenation at the 1-position

could be achieved by way of xanthate formation and

n-Bu₃SnH reduction.

2.2. Biological testing

All synthesized analogues were puriﬁed by preparative re-

verse phase HPLC. Reporter assays were carried out uti-

lizing luciferase activity. The fusion protein was used for

assays, which consist of DNA-binding domain of Gal4

Another reference compounds, 1-hydroxymethyl-25-

hydroxyvitamin D₃(4a,b), could be also prepared sub-

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S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

MeO

O

MeO

O

MeO

O

TFA-Et₃SiH-MS3A

O

1) LiAlH₄

2) TBSCl

OBn

OH

O

Ph

TBSO

O

Ph

O

7

24 88% (2 steps)

76%

25

MeO

TBSO

O

MeO

O

OBn

1) TPAP, NMO

2) Zn-CH₂Br₂-TiCl₄

1) BH₃•THF

OBn

OH

2) NaOH, H₂O₂

TBSO

26 63% (2 steps)

27a

27b

(Less polar isomer) 72% (2 steps)

(More polar isomer) 8% (2 steps)

1) TPAP, NMO

2) K₂CO₃, MeOH

3) NaBH₄

59%

(+ 27a 15 %)

HO

MeO

O

1) PivCl

Zn, NaBH₃CN

1) TsCl

Br

OPiv

2) H₂, Pd(OH)₂/C

3) MsCl, Et₃N

4) LiBr, TMU

2) TBAF

TBSO

29a 75%

29b

28a 59% (4 steps)

28b 77% (4 steps)

61%

1)

Li

TMS

TBSOTf, 2,6-lutidine

BF₃OEt₂

O

OH

OPiv

HO

2) NaOMe, MeOH

30a

30b

70% (2 steps)

75% (2 steps)

31a

79% (2 steps)

31b 80% (2 steps)

OH

H

OH

H

1)

H

6

Br

OTBS

TBSO

H

Pd(PPh₃)₄, PhMe-Et₃N

2) HF-Py

32a

76%

32b 85%

OH

HO

4a

4b

39% (2 steps)

64% (2 steps)

Scheme 4. Synthesis of 2-unsubstituted analogues 4a and 4b.

OH

H

1.2%

4b (from more polar isomer 27b)

H

4a (from less polar isomer 27a)

H

3

H

(1β,3β)

Undesired

Configuration

(1α,3β)

Desired Configuration

HO

3

1

2

1

OH

HO

H

2 H

HO

irr.

Figure 4. Determination of the stereochemistry of 2-unsubstituted analogues.

(transcription factor protein of Saccharomyces cerevisiae)

and human VDR LBD.¹⁸Site-directed mutagenesis was

conducted to construct the LBD of Arg274Leu, and re-

porter assays were carried out by using both wild type

and mutant VDR. Other than the analogues synthesized

above, 2a-(3-hydroxypropyl)-1a,25(OH)₂D₃(5)^8band

25-hydroxyvitamin D₃(25(OH)D₃) were also assayed in

order to compare the eﬀects of 1- and 2a-substituents.

(2a,b and 4a,b) were found to be rather less eﬀective than

the natural hormone 1, irrespective of the presence of

the 2a-(3-hydroxypropyl) group (Table 1). The results

could be expected because of steric hindrance of the

1-hydroxymethyl group. When the eﬀect of the 2a-(3-

hydroxypropyl) group was compared in the series of

1-hydroxymethylated analogues (2a,b and 4a,b), the

transcriptional activities were lower at 10^ꢀ8M by the

introduction of 2a-(3-hydroxypropyl) group in both

the 1a- and 1b-hydroxymethyl analogues (Table 2).

The A-ring of 4a,b might be located at the diﬀerent

As shown in Figure 5, when assays were performed on

the wild type VDR, the 1-hydroxymethylated analogues

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3007

-8

2α-CH₂CH₂CH₂OH

2α-H

10

M

14

13

12

11

10

9

-7

10^-8

10^-7

10^-6

M

13

10

-6

12

11

10

9

10

8

7

6

5

4

3

2

1

0

1

25(OH) 4a

4b

2a

2b

3

5

1

25(OH) 4a

4b

2a

2b

3

5

Figure 5. Reporter assays for wild type VDR (n = 3, means SD).

Figure 6. Reporter assays for mutant VDR(Arg274Leu) (n = 3,

means SD).

position from the A-ring of 1 in the LBD, and the 2a-(3-

hydroxypropyl) group of 4a,b does not work as a posi-

tive motif for binding to the wild type VDR. Comparing

the activities of 5 with its 1-deoxy analogue, 3, the tran-

scriptional activity of 3 was lower at 10^ꢀ8M, similar to

the case in the 2-unsubstituted series (i.e., 1 and

25(OH)D₃), previously reported in SAR studies.¹This

conﬁrms that the presence of the 1a-OH group is very

important for vitamin D action even in the presence of

the 2a-(3-hydroxypropyl) group.

The fact that the hydrogen bond between the 1a-OH

group of 1 and Arg274 in the wild type receptor LBD

plays an important role for vitamin D action has been

supported by an X-ray diﬀraction study,³and alanine

scanning mutational analysis²⁰has also demonstrated

the importance of the hydrogen bond. Destruction of

this hydrogen bond would result in reduction of the

aﬃnity between the analogues and the mutant receptor.

We planned to create a hydrophobic interaction between

an alternative substituent at the 1-position and the

hydrophobic cavity formed by the mutation. This ap-

proach has been formally applied by Koh’s group,

who synthesized and assayed 1-O-benzyl analogues of

1.^6aPosner and co-workers have reported on 1a-

hydroxymethyl analogues with reduced calcemic ac-

tion,^7,21an interesting feature among the vitamin D

derivatives that retain non-classical activity. We chose

to model our target compounds initially on Posner’s

compounds and to examine the eﬀect of a 2a-substituent

on aﬃnity to the mutant VDR. In the case of the 2-

unsubstituted series, the 1a-hydroxymethyl analogue

was most eﬀective (Table 1). However, in the case of

the 2a-substituted series, modiﬁcation at the 1-position

was not critical, that is, the activities of 1a-hydroxyme-

thylated 2b, 1a-unsubstituted 3, and 1a-hydroxylated 5

were similar (Table 1). We assumed that this averaging

eﬀect of the activities of the 1-substituted analogues

When the mutant receptor (Arg274Leu) was assayed

(Fig. 6), the replacement of the 1a-hydroxy group of 1

to the 1a-hydroxymethyl group (4b) appears to increase

its transcriptional activities. While the introduction of

the 1b-hydroxymethyl group (4a) showed little eﬀect

(Table 1). In contrast, in the 2a-substituted series, the ef-

fect of the substituent at the 1-position appeared not to

be so dramatic (compare 2b, 3, and 5 in Figure 6 and

Table 1), which may imply that an attractive interaction

between the terminal OH group of the 2a-(3-hydroxy-

propyl) group and sites in the mutant receptor plays

the dominant role, and accordingly, this substituent

could represent an active motif for the mutant receptor

as the 1a-OH group does for the wild type.

The recovery of the aﬃnity by another attractive inter-

action was the theme of the paper published recently.¹⁹

Table 1. Summary of the eﬀects of the 1a-substituent of the vitamin D₃derivatives on the transcriptional activities mediated by wild type/mutant

VDR

2a-Substituent

Wild type VDR

Mutant VDR

–(CH₂)₃OH

H ꢁ 1b-CH₂OH 6 1a-CH₂OH < 1a-OH

3 ꢁ 2a 6 2b < 5

1b-CH₂OH < 1a-CH₂OH ꢁ H ꢁ 1a-OH

2a < 2b ꢁ 3 ꢁ 5

–H

H < 1b-CH₂OH < 1a-CH₂OH < 1a-OH

25(OH)D₃< 4a < 4b < 1

1a-OH ꢁ 1b-CH₂OH < H < 1a-CH₂OH

1 ꢁ 4a < 25(OH)D₃< 4b

Table 2. Summary of the eﬀects of the 2a-substituent of the vitamin D₃analogues on the transcriptional activities mediated by wild type/mutant

VDR

1-Substituent

Wild type VDR

Mutant VDR

a-CH₂OH

b-CH₂OH

a-OH

H (4b) P 2a-(CH₂)₃OH (2b)

H (4a) P 2a-(CH₂)₃OH (2a)

H (1) < 2a-(CH₂)₃OH (5)

H (4b) ꢁ 2a-(CH₂)₃OH (2b)

H (4a) < 2a-(CH₂)₃OH (2a)

H (1) < 2a-(CH₂)₃OH (5)

H

H (25(OH)D₃) ꢁ 2a-(CH₂)₃OH (3)

H (25(OH)D₃) < 2a-(CH₂)₃OH (3)

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S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

would result from insuﬃciencies in promoting attractive

interaction by hydrophobic interaction induced by the 1-

substitution. In the absence of the 2a-(3-hydroxypropyl)

group, subtle steric diﬀerences around the 1-position

would be eﬀectively recognized by the mutant

receptor.²²

VDR(Arg274Leu), and found that the 2a-(3-hydroxy-

propyl) group, rather than the 1-modiﬁcation, had a lar-

ger enhancing eﬀect on transcriptional activity. We

suggest that the 2a-(3-hydroxypropyl) group could be

a universal active motif of vitamin D derivatives as ago-

nists for the mutant VDR. Further research is now in

progress in order to optimize the ligands for the mutant

receptor by introducing larger and more hydrophobic

substituents at the 1-position.

As noted above, the 1a-OH group of 1 forms hydrogen

bond with Arg274 of the wild type VDR, and this

hydrogen bond plays an important role in the complex-

ation of the vitamin D analogues with the receptor. This

strong hydrogen bond deﬁnes the conformation of the

A-ring of the vitamin D analogues in an appropriate

manner, in the b-form, to form the strong complex. In

the mutant VDR in which the polar Arg274 is absent,

the hydrogen bond would not be formed, and the con-

formation of the A-ring might not necessarily be the

same as that of the wild type VDR complex. This con-

formational change would modify the projection of the

2a-(3-hydroxypropyl) group, which could be one of

the reasons for the diﬀerences of the activities of 2b

and 4b (between in the presence and in the absence of

2a-(3-hydroxypropyl) group). That might be the case

for 1-deoxy derivatives 25(OH)D₃and 3, in which the

conformational preference might be small because of

the steric eﬀects of small substituent (H). The eﬀect of

the 1a-hydroxymethyl group would be compounded

onto the conformational changes of the A-ring moiety.

Hydrophobic interactions could be an important factor

for complexation, but a hydrogen bond between the OH

group of the 1a-hydroxymethyl group and the Ile271

would assist the conformational changes. These confor-

mational changes are supported by molecular modeling

studies (Figs. 7a and b). In the latter case, 2b, OH group

of the 2a-(3-hydroxypropyl) group could no longer form

a hydrogen bond. These complex substitution eﬀects

may explain the activities of the analogues toward the

mutant receptor. It is not easy task to compensate for

the stronger hydrogen bond by hydrophobic interac-

tions, but this could be overcome by introducing much

larger hydrophobic substituent which ﬁts more appro-

priately into the hydrophobic pocket.

3. Experimental

Melting points were determined with a Yanagimoto

micromelting point apparatus without correction. Opti-

cal rotations were measured on a JASCO DIP-370 digital

polarimeter. IR spectra were measured on a JASCO FT/

IR-800 spectrophotometer. ¹H NMR and ¹³C NMR

spectra were recorded on a JEOL AL-400 NMR

(400 MHz) or ECP-600 NMR (600 MHz) with Me₄Si

as an internal standard. ¹³C NMR spectra taken in

CDCl₃(d 77.0) were referenced to the residual solvents.

Low- and high-resolution mass spectra were recorded

on a JEOL JMX-SX 102A spectrometer. FAB mass

spectra were measured using m-nitrobenzyl alcohol

matrix. Elemental analyses were conducted with a

Perkin-Elmer PE 2400II CHNS/O analyzer. Column

chromatography was performed on silica gel 60N (Kanto

Chemical Co., Inc., 100–210 lm) or silica gel 60 (Merck,

0.040–0.063 mm). Preparative thin layer chromatogra-

phy was performed on silica gel 60 F₂₅₄(Merck, 0.5 mm).

Sugar epoxide 7 was synthesized according to the litera-

ture procedure.^13,14

3.1. Synthesis of 1a- and 1b-hydroxymethyl-2a-hydroxy-

propylated analogues (2a,b)

3.1.1. Methyl 3-C-Allyl-4,6-O-benzylidene-2-O-tert-

butyldimethylsilyl-3-deoxy-a-^D-altropyranoside. A mix-

ture of C-allylated starting alcohol^8e(derived from the

sugar epoxide 7, 5.47 g, 17.9 mmol), imidazole (6.08 g,

89.3 mmol), TBSCl (10.0 g, 66.3 mmol) in DMF

(15 mL) was stirred at room temperature for 13 h. The

mixture was diluted with Et₂O (50 mL) and washed with

In conclusion, we have synthesized and assayed 1- and

2a-doubly modiﬁed vitamin D analogues for the mutant

Figure 7. Computer-generated models of the complexes between the mutant VDR(Arg274Leu) and 4b (a), or 2b (b).

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3009

water (2· 50 mL) and brine (50 mL). The organic layer

was dried (Na₂SO₄), and concentrated. Puriﬁcation by

silica gel column chromatography (hexane/AcOEt

(25:1)) gave the TBS ether (7.37 g, 98%) as a colorless

oil.

was cooled to 0 ꢁC, and additional PivCl (1.9 mL,

15.4 mmol) was added, which was stirred at 0 ꢁC, and

gradually raised up to room temperature for 3.5 h.

The solvent was removed under reduced pressure, and

the residue was partitioned between Et₂O (50 mL) and

saturated aqueous NaHCO₃solution (50 mL). Layers

were separated, and the aqueous layer was extracted

with Et₂O (20 mL). The combined organic layers were

washed with water (50 mL) and brine (50 mL), dried

(Na₂SO₄), and concentrated. Puriﬁcation by silica gel

column chromatography (hexane/AcOEt (10:1)) gave

the pivalate 8 (6.51 g, 95%) as a colorless oil.

17

D

½aꢂ +40.5ꢁ (c 1.8, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (3H, s), 0.06 (3H, s), 0.90 (9H, s), 2.11 (1H,

m), 2.44–2.58 (2H, m), 3.36 (3H, s), 3.78 (1H, dd,

J = 10.0, 10.0 Hz), 3.91 (1H, s), 3.93 (1H, ddd, J = 4.9,

10.0, 10.0 Hz), 4.13 (1H, dd, J = 5.8, 10.0 Hz), 4.26

(1H, dd, J = 4.9, 10.0 Hz), 4.46 (1H, s), 5.04–5.15 (2H,

m), 5.61 (1H, s), 5.82 (1H, dddd, J = 6.5, 7.9, 10.3,

16.8 Hz), 7.32–7.40 (3H, m), 7.46–7.52 (2H, m). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.8, 18.1,

25.9, 28.8, 43.1, 55.1, 59.4, 69.7, 69.8, 76.2, 102.0,

102.9, 116.8, 126.2, 128.2, 129.0, 137.2, 137.8. IR

(neat, cm^ꢀ1) 2930, 1642, 1468, 1258, 1102, 1051, 853,

776, 698. LRMS (EI(+)) m/z 420 (M⁺), 419 (M⁺ꢀ1),

389 ([MꢀOMe]⁺), 363 ([Mꢀt-Bu]⁺), 331 ([Mꢀt-

BuꢀMeOH]⁺), 271, 257, 225 (bp), 141. HRMS (EI(+))

calcd for C₂₃H₃₆O₅Si (M⁺) 420.2332, found 420.2320.

21

D

½aꢂ +45.8ꢁ (c 0.8, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.08 (3H, s), 0.09 (3H, s), 0.92 (9H, s), 1.19 (9H,

s), 1.46–1.72 (1H, m), 1.72–1.90 (3H, m), 2.00–2.09 (1H,

m), 3.34 (3H, s), 3.77 (1H, dd, J = 10.1, 10.1 Hz), 3.87

(1H, m), 3.92 (1H, ddd, J = 5.0, 10.1, 10.1 Hz), 4.02–

4.18 (3H, m), 4.25 (1H, dd, J = 5.0, 10.1 Hz), 4.45

(1H, s), 5.59 (1H, s), 7.32–7.39 (3H, m), 7.44–7.51

(2H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.5,

ꢀ4.5, 18.4, 21.4, 26.2, 27.5, 28.1, 39.1, 43.8, 55.3, 59.7,

64.7, 70.0, 71.0, 76.7, 102.2, 103.0, 116.8, 126.5, 128.5,

129.2, 138.1, 178.7. IR (neat, cm^ꢀ1) 2932, 1730, 1464,

1285, 1156, 1105, 1049, 853, 841, 777. LRMS (EI(+))

m/z 522 (M⁺), 521 ([MꢀH]⁺), 491 ([MꢀMeO]⁺), 465

([Mꢀt-Bu]⁺), 447, 433 ([Mꢀt-BuꢀMeOH]⁺), 363, 341,

159 (bp). HRMS (EI(+)) calcd for C₂₈H₄₆O₇Si (M⁺)

522.3013, found 522.3021.

3.1.2. Methyl 4,6-O-benzylidene-2-O-tert-butyldimethyl-

silyl-3-deoxy-3-C-(3-hydroxypropyl)-a-^D-altropyranoside.

To a solution of oleﬁn prepared as above (7.37 g,

17.5 mmol) in THF (10 mL) was added BH₃ÆTHF

(1 M in THF, 35 mL, 35 mmol) at 0 ꢁC. The mixture

was stirred at the same temperature for 2 h. Aqueous

1 N NaOH solution (25 mL) was added dropwise, fol-

lowed by 30% aqueous H₂O₂solution (25 mL). The mix-

ture was stirred at 0 ꢁC for 3 h and poured into 10%

aqueous Na₂S₂O₃solution (50 mL). The mixture was ex-

tracted with AcOEt (2· 50 mL) and organic layers were

combined, washed with 10% aqueous Na₂S₂O₃solution

(50 mL), water (50 mL), brine (50 mL), dried (Na₂SO₄),

and concentrated. Puriﬁcation by silica gel column chro-

matography (hexane/AcOEt (20:1 to 2:1)) gave the alco-

hol (5.71 g, 77%) as a colorless oil.

3.1.4. Methyl 6-O-Benzyl-2-O-tert-butyldimethylsilyl-3-

deoxy-3-C-(3-pivaloyloxypropyl)-a-^D-altropyranoside (9).

Under an Ar atmosphere, to a cooled (0 ꢁC) mixture of

benzylidene acetal

8 (6.51 g, 12.5 mmol), Et₃SiH

(15 mL, 93.9 mmol), MS3A (12.4 g) in CH₂Cl₂(75 mL)

was added TFA (7.2 mL, 93.5 mmol) and stirred at

room temperature for 6 h. Another Et₃SiH (15 mL,

9.39 mmol) and TFA (7.2 mL, 93.5 mmol) were added,

and stirred at room temperature for 2 h. The mixture

was cooled in ice-water bath, the reaction was quenched

by slow addition of saturated aqueous Na₂CO₃solution

(100 mL), and the mixture was stirred at room tempera-

ture for 30 min. The mixture was ﬁltered through Celite,

washed with CH₂Cl₂and water, and the layers were sep-

arated. The aqueous layer was extracted with CH₂Cl₂

(2· 30 mL), and organic layers were combined, washed

with brine (50 mL), dried (Na₂SO₄), and concentrated.

Puriﬁcation by silica gel column chromatography (hex-

ane/AcOEt (5:1 to 1:1)) gave desired alcohol 9 (3.86 g,

59%) as a colorless oil.

19

D

½aꢂ +44.7ꢁ (c 1.0, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.09 (3H, s), 0.09 (3H, s), 0.92 (9H, s), 1.54–1.65

(1H, m), 1.66–1.85 (3H, m), 2.03–2.10 (1H, m), 3.35 (3H,

s), 3.65 (2H, t, J = 6.8 Hz), 3.77 (1H, dd, J = 10.0,

10.0 Hz), 3.91 (1H, s), 3.94 (1H, ddd, J = 5.1, 10.0,

10.0 Hz), 4.12 (1H, dd, J = 5.1, 10.0 Hz), 4.26 (1H, dd,

J = 5.1, 10.0 Hz), 4.45 (1H, s), 5.59 (1H, s), 7.32–7.40

(3H, m), 7.46–7.51 (2H, m). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ4.9, ꢀ4.8, 18.1, 20.6, 25.9, 31.6, 43.4,

55.1, 59.4, 63.0, 69.7, 70.8, 76.6, 102.0, 102.6, 126.2,

128.2, 129.0, 137.7. IR (neat, cm^ꢀ1) 3441, 2930, 1466,

1385, 1258, 1107, 1046, 841, 777, 698. LRMS (EI(+))

m/z 438 (M⁺), 437 (M⁺ꢀ1), 407 ([MꢀOMe]⁺), 381

([Mꢀt-Bu]⁺), 349 ([Mꢀt-BuꢀMeOH]⁺), 275, 243, 159

(bp). HRMS (EI(+)) calcd for C₂₃H₃₈O₆Si (M⁺)

438.2438, found 438.2435.

17

D

½aꢂ +21.1ꢁ (c 0.9, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (3H, s), 0.06 (3H, s), 0.89 (9H, s), 1.20 (9H,

s), 1.54–1.83 (5H, m), 2.41 (1H, br s), 3.35 (3H, s), 3.63

(1H, dd, J = 6.0, 9.6 Hz), 3.68 (1H, dd, J = 2.4, 6.0 Hz),

3.73 (1H, dd, J = 4.8, 9.6 Hz), 3.82 (1H, m), 4.03 (1H,

dd, J = 4.4, 7.2 Hz), 4.03–4.12 (2H, m), 4.41 (1H, d,

J = 2.4 Hz), 4.57 (1H, d, J = 12.0 Hz), 4.63 (1H, d,

J = 12.0 Hz), 7.26–7.39 (5H, m). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ4.8, ꢀ4.6, 18.1, 21.3, 25.9, 27.1, 27.3,

38.8, 43.3, 55.2, 64.6, 67.8, 69.9, 71.4, 71.5, 73.7, 103.5,

127.7, 127.8, 128.4, 137.7, 178.5. IR (neat, cm^ꢀ1) 3486,

2930, 1729, 1472, 1287, 1252, 1159, 1111, 1051, 837,

3.1.3. Methyl 4,6-O-Benzylidene-2-O-tert-butyldimethyl-

silyl-3-deoxy-3-C-(3-pivaloyloxypropyl)-a-^D-altropyrano-

side (8). To a solution of alcohol prepared as above

(5.57 g, 13.1 mmol) in pyridine (50 mL) was added PivCl

(1.9 mL, 15.4 mmol) and stirred at 0 ꢁC, and gradually

raised up to room temperature for 24 h. The mixture

3010

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

777. LRMS (EI(+)) m/z 493 ([MꢀMeO]⁺), 492

([MꢀMeOH]⁺), 475 ([MꢀMeOꢀH₂O]⁺), 449 ([Mꢀt-

BuꢀH₂O]⁺), 435 ([Mꢀt-BuꢀMeOH]⁺), 417 ([Mꢀt-

BuꢀH₂OꢀMeOH]⁺), 341, 243, 159 (bp), 91 (C₇H₇).

HRMS (EI(+)) calcd for C₂₇H₄₅O₆Si ([MꢀMeO]⁺)

493.2985, found 493.2974.

7.36 (5H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d

ꢀ4.9, ꢀ4.5, 18.1, 24.2, 25.9, 26.5, 27.3, 38.8, 44.9, 55.4,

64.5, 70.7, 72.4, 73.4, 77.2, 105.0, 109.7, 127.5, 127.5,

128.2, 138.2, 144.2, 178.5. IR (neat, cm^ꢀ1) 2930, 1730,

1462, 1285, 1254, 1157, 1113, 1051, 837, 777. LRMS

(EI(+)) m/z 520 (M⁺), 505 ([MꢀMe]⁺), 489

([MꢀOMe]⁺), 473 ([MꢀMeꢀMeOH]⁺), 463 ([Mꢀt-

Bu]⁺), 431 ([Mꢀt-BuꢀMeOH]⁺), 399 ([MꢀBnOCH₂]⁺),

352, 341, 159, 91 (C₇H₇, bp). HRMS (EI(+)) calcd for

C₂₉H₄₈O₆Si (M⁺) 520.3220, found 520.3204.

3.1.5. 3-[(2R,4S,5S,6S)-2-Benzyloxymethyl-5-(tert-butyldi-

methylsilyloxy)-6-methoxy-3-oxotetrahydropyran-4-yl]pro-

pyl pivalate. Under an Ar atmosphere, a mixture of alcohol

9 (3.86 g, 7.36 mmol), NMO (1.33 g, 7.51 mmol), TPAP

(256.7 mg, 0.73 mmol) in CH₂Cl₂(75 mL) was stirred at

room temperature for 2.5 h. The solvent was removed un-

der reduced pressure, and the residue was puriﬁed by silica

gel column chromatography (hexane/AcOEt (10:1)) to give

the ketone (3.29 g, 86%) as a colorless oil.

3.1.7. Hydroboration of 10 followed by re-protection as

pivalate. Under an Ar atmosphere, to a cold (0 ꢁC) solu-

tion of oleﬁn 10 (2.27 g, 4.36 mmol) in THF (15 mL)

was added BH₃ÆTHF (1 M in THF, 13 mL, 13 mmol).

Reaction temperature was gradually raised up to room

temperature, and the mixture was stirred for 9.5 h.

The mixture was cooled to 0 ꢁC, and 3 M NaOAc

(10 mL) and 30% H₂O₂(10 mL) were added. After stir-

red at room temperature overnight, the reaction was

quenched by the addition of 10% aqueous Na₂S₂O₃

solution (50 mL) at 0 ꢁC. The mixture was extracted

with AcOEt (2· 25 mL) and the organic layers were

combined, washed with 10% aqueous Na₂S₂O₃solution

(25 mL), brine (25 mL), dried (Na₂SO₄), and concen-

trated. The residue was dissolved in pyridine (20 mL)

and PivCl (2 mL, 16.9 mmol) was added. After stirred

at room temperature for 11 h, the solvent was removed

under reduced pressure. The residue was diluted with

water (20 mL) and extracted with AcOEt (2· 20 mL).

The organic layers were combined, washed with water

(20 mL), brine (20 mL), dried (Na₂SO₄), and concen-

trated. Puriﬁcation by silica gel column chromatography

(hexane/AcOEt (20:1)) gave 11a (less polar isomer,

1.16 g, 43%) and 11b (more polar isomer, 904.1 mg,

33%) as colorless oils, respectively.

16

D

½aꢂ +96.5ꢁ (c 1.2, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.07 (3H, s), 0.09 (3H, s), 0.90 (9H, s), 1.19 (9H, s),

1.50–1.84 (4H, m), 2.83 (1H, ddd, J = 3.3, 7.5, 10.6 Hz),

3.40 (3H, s), 3.50 (1H, dd, J = 2.8, 10.6 Hz), 3.77 (1H,

dd, J = 2.8, 10.4 Hz), 3.83 (1H, dd, J = 4.4, 10.4 Hz),

3.98–4.09 (3H, m), 4.52 (1H, d, J = 12.0 Hz), 4.59 (1H,

d, J = 12.0 Hz), 4.77 (1H, d, J = 2.8 Hz), 7.24–7.38 (5H,

m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ5.0, ꢀ4.5,

18.0, 21.2, 25.8, 26.6, 27.3, 38.7, 52.5, 55.4, 64.6, 69.6,

73.6, 75.0, 75.5, 105.7, 127.5, 127.6, 128.3, 137.7, 178.4,

210.4. IR (neat, cm^ꢀ1) 2957, 1730, 1474, 1456, 1159,

1113, 1042, 837, 777. LRMS (EI(+)) m/z 522 (M⁺), 465

([Mꢀt-Bu]⁺), 433 ([Mꢀt-BuꢀMeOH]⁺), 386, 363, 343,

255, 159, 91 (C₇H₇, bp). HRMS (EI(+)) calcd for

C₂₈H₄₆O₇Si (M⁺) 522.3013, found 522.3013.

3.1.6. 3-[(2S,4R,5S,6S)-2-Benzyloxymethyl-5-(tert-butyl-

dimethylsilyloxy)-6-methoxy-3-methylenetetrahydropy-

ran-4-yl]propyl pivalate (10). Under an Ar atmosphere,

to a cold (ꢀ40 ꢁC) mixture of Zn dust (activated by

sequential treatment of 1 N HCl aq, water, EtOH, and

Et₂O, and then dried in vacuo, 5.88 g, 88.7 mmol),

CH₂Br₂(2.1 mL, 29.9 mmol) in THF (50 mL) was

added TiCl₄(2.3 mL, 21.0 mmol) dropwise and stirred

at 5 ꢁC (in a cold room) for 3 d. The mixture was diluted

with CH₂Cl₂(20 mL) and ketone prepared as above

(3.14 g, 6.00 mmol) in CH₂Cl₂(25 mL) was added. After

stirred at room temperature for 9.5 h, the mixture was

poured into a mixture of Et₂O (100 mL) and saturated

aqueous NaHCO₃solution (100 mL) and vigorously

stirred for several minutes. The mixture was ﬁltered

through Celite, washed with CH₂Cl₂and water, and

the layers were separated. The organic layer was washed

with water (100 mL) and brine (100 mL), dried

(Na₂SO₄), and concentrated. Puriﬁcation by silica gel

column chromatography (hexane/AcOEt (10:1)) gave

oleﬁn 10 (2.27 g, 73%) as a colorless oil.

3.1.8. 3-[(2S,3S,4R,5S,6S)-2-Benzyloxymethyl-5-(tert-

butyldimethylsilyloxy)-6-methoxy-3-pivaloyloxymethyltetr-

19

D

ahydropyran-4-yl]propyl pivalate (11a). ½aꢂ +23.2ꢁ (c 0.7,

1

CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.06 (6H,

s), 0.89 (9H, s), 1.15 (9H, s), 1.20 (9H, s), 1.50–1.81

(6H, m), 3.37 (3H, s), 3.48 (1H, s), 3.56 (1H, dd,

J = 2.8, 10.5 Hz), 3.64 (1H, dd, J = 8.5, 10.5 Hz), 4.06

(2H, apparent dt, J = 3.2, 6.2 Hz), 4.18 (1H, dt, J = 8.5,

2.8 Hz), 4.22 (1H, dd, J = 5.6, 11.3 Hz), 4.44 (1H, dd,

J = 7.8, 11.3 Hz), 4.51 (1H, d, J = 12.0 Hz), 4.52 (1H,

s), 4.67 (1H, d, J = 12.0 Hz), 7.24–7.38 (5H, m). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ4.9, ꢀ4.9, 18.0,

25.8, 27.2, 27.5, 37.9, 38.6, 38.8, 41.6, 54.7, 64.0, 65.0,

65.1, 69.6, 72.2, 73.4, 102.7, 127.4, 127.4, 128.2, 138.3,

178.0, 178.3. IR (neat, cm^ꢀ1) 2934, 1730, 1478, 1285,

1156, 1119, 1034, 857, 839, 777. LRMS (EI(+)) m/z 591

([MꢀOMe]⁺), 590 ([MꢀMeOH]⁺), 533 ([Mꢀt-

BuꢀMeOH]⁺), 431, 341, 243, 221, 159 (bp), 91 (C₇H₇).

HRMS (EI(+)) calcd for C₃₃H₅₅O₇Si ([MꢀOMe]⁺)

591.3717, found 591.3721.

18

D

½aꢂ +42.2ꢁ (c 1.0, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (6H, s), 0.89 (9H, s), 1.20 (9H, s), 1.48–1.65

(2H, m), 1.65–1.82 (2H, m), 2.28 (1H, m), 3.32 (1H, dd,

J = 1.8, 8.0 Hz), 3.39 (3H, s), 3.63 (1H, dd, J = 4.6,

10.2 Hz), 3.67 (1H, dd, J = 6.6, 10.2 Hz), 4.04 (2H, t,

J = 6.0 Hz), 4.39 (1H, apparent t, J = 5.4 Hz), 4.57

(1H, d, J = 1.8 Hz), 4.58 (1H, d, J = 12.6 Hz), 4.64

(1H, d, J = 12.6 Hz), 4.90 (1H, s), 4.98 (1H, s), 7.25–

3.1.9. 3-[(2S,3R,4R,5S,6S)-2-Benzyloxymethyl-5-(tert-

butyldimethylsilyloxy)-6-methoxy-3-pivaloyloxymethyltetr-

20

D

ahydropyran-4-yl]propyl pivalate (11b). ½aꢂ +26.0ꢁ (c 0.5,

1

CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.05 (3H,

s), 0.06 (3H, s), 0.89 (9H, s), 1.16 (9H, s), 1.19 (9H, s),

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3011

1.58–1.94 (5H, m), 2.46 (1H, m), 3.35 (3H, s), 3.55–3.64

(3H, s), 3.87 (1H, m), 3.97–4.11 (4H, m), 4.47 (1H, d,

J = 2.4 Hz), 4.57 (1H, d, J = 10.2 Hz), 4.62 (1H, d,

J = 10.2 Hz), 7.25–7.38 (5H, m). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ4.8, ꢀ4.5, 18.1, 22.3, 25.9, 27.2, 27.2,

27.3, 34.6, 38.8, 40.0, 55.1, 62.5, 64.5, 67.6, 69.8, 71.4,

73.4, 103.3, 127.5, 128.3, 138.2, 178.1, 178.4. IR (neat,

cm^ꢀ1) 2932, 1730, 1480, 1460, 1285, 1156, 1107, 1053,

839, 776. LRMS (EI(+)) m/z 591 ([MꢀOMe]⁺), 590

([MꢀMeOH]⁺), 533 ([Mꢀt-BuꢀMeOH]⁺), 489, 463,

431, 341, 243, 159 (bp), 91 (C₇H₇). HRMS (EI(+)) calcd

for C₃₃H₅₅O₇Si ([MꢀOMe]⁺) 591.3717, found 591.3707.

4.47 (1H, d, J = 2.0 Hz), 4.49 (1H, dd, J = 2.5,

11.6 Hz). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8,

ꢀ4.7, 18.0, 22.0, 25.8, 27.2, 27.2, 33.6, 37.9, 38.7, 38.8,

40.5, 55.3, 62.6, 64.2, 66.3, 68.7, 70.9, 103.0, 177.9,

178.3. IR (neat, cm^ꢀ1) 2936, 1730, 1482, 1362, 1254,

1177, 1154, 837, 777. LRMS (EI(+)) m/z 579

([MꢀOMe]⁺), 578 ([MꢀMeOH]⁺), 521 ([Mꢀt-

BuꢀMeOH]⁺), 477, 451, 419, 159 (bp). HRMS (EI(+))

calcd for C₂₇H₅₁O₉SSi ([MꢀOMe]⁺) 579.3023, found

579.3044.

3.3. Synthesis of bromide 13a,b

3.2. Synthesis of 12a,b

Under an Ar atmosphere, a mixture of mesylate 12a

(1.15 g, 1.88 mmol), LiBr (1.06 g, 12.2 mmol) in TMU

(1,1,3,3-tetramethylurea, 9 mL) was stirred at 80 ꢁC for

6.5 h. After cooled to room temperature, the mixture

was diluted with water (20 mL) and extracted with

Et₂O (2· 20 mL). The organic layers were combined,

washed with brine (20 mL), dried (Na₂SO₄), and con-

centrated. Puriﬁcation by silica gel column chromatog-

raphy (hexane/AcOEt (20:1)) gave bromide 13a

(1.01 g, 91%) as a colorless oil.

A mixture of 11a (1.16 g, 1.86 mmol), Pd(OH)₂/C (20%

dry basis, 58.6 mg) in EtOH (5 mL) was stirred under

H₂atmosphere at room temperature for 4 h. The catalyst

was ﬁlteredoﬀ andconcentrated. The residue was dried by

azeotroping with PhMe and diluted with CH₂Cl₂(5 mL).

The solution was cooled to 0 ꢁC, and Et₃N (310 lL,

2.22 mmol) and MsCl (145 lL, 1.83 mmol) were added.

After stirred at 0 ꢁC, for 40 min, another Et₃N (100 lL,

0.72 mmol) and MsCl (50 lL, 0.65 mmol) were added

and stirred at the same temperature for further 30 min.

The reaction was quenched by the addition of water

(10 mL) and extracted with AcOEt (2· 10 mL). The or-

ganic layers were combined, washed with brine (10 mL),

dried (Na₂SO₄), and concentrated to give mesylate 12a

(1.15 g, quant.) as a colorless oil.

3.3.1. 3-[(2S,3S,4R,5S,6S)-2-Bromomethyl-5-(tert-butyl-

dimethylsilyloxy)-6-methoxy-3-pivaloyloxymethyltetra-

22

D

hydropyran-4-yl]propyl pivalate (13a). ½aꢂ +48.1ꢁ (c 0.7,

1

CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.06 (6H,

s), 0.90 (9H, s), 1.19 (9H, s), 1.21 (9H, s), 1.44–1.87 (6H,

m), 3.42 (3H, s), 3.46 (1H, dd, J = 4.0, 10.7 Hz), 3.47

(1H, m), 3.54 (1H, dd, J = 9.3, 10.7 Hz), 4.06 (1H, dt,

J = 10.7, 6.3 Hz), 4.09 (1H, dt, J = 10.7, 6.3 Hz), 4.17

(1H, apparent dt, J = 9.3, 3.0 Hz), 4.22 (1H, dd, J = 4.4,

11.7 Hz), 4.48 (1H, dd, J = 8.4, 11.7 Hz), 4.52 (1H, s).

¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ5.0, ꢀ4.9, 18.0,

25.8, 27.2, 27.3, 27.4, 27.5, 34.3, 38.6, 38.8, 39.5, 42.4,

55.2, 63.9, 64.9, 66.7, 69.2, 103.3, 178.0, 178.3. IR (neat,

cm^ꢀ1) 2932, 1730, 1480, 1283, 1157, 1034, 839, 776.

LRMS (EI(+)) m/z 563 ([M(⁷⁹Br)ꢀOMe]⁺), 537

([M(⁷⁹Br)ꢀt-Bu]⁺), 505 ([Mꢀt-BuꢀMeOH]⁺), 461, 435,

353, 159 (bp). HRMS (EI(+)) calcd for C₂₆H₄₈⁷⁹BrO₆Si

([M(⁷⁹Br)ꢀOMe]⁺) 563.2404, found 563.2397.

3.2.1. 3-[(2S,3S,4R,5S,6S)-5-(tert-Butyldimethylsilyl-

oxy)-2-methanesulfonyloxymethyl-6-methoxy-3-pivaloyl-

oxymethyltetrahydropyran-4-yl]propyl pivalate (12a).

22

D

½aꢂ +39.6ꢁ (c 1.4, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.07 (6H, s), 0.91 (9H, s), 1.19 (9H, s), 1.21 (9H,

s), 1.48–1.60 (1H, m), 1.60–1.84 (5H, m), 3.05 (3H, s),

3.35 (3H, s), 3.49 (1H, br s), 4.05 (1H, dt, J = 10.9,

6.2 Hz), 4.09 (1H, dt, J = 10.9, 6.2 Hz), 4.17 (1H, dd,

J = 4.0, 11.8 Hz), 4.24 (1H, m), 4.29 (1H, dd, J = 2.8,

11.2 Hz), 4.34 (1H, dd, J = 9.2, 11.2 Hz), 4.49 (1H, s),

4.52 (1H, dd, J = 8.8, 11.8 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ5.0, ꢀ4.8, 18.0, 25.8, 27.2, 27.3, 27.5,

37.5, 37.9, 38.7, 38.8, 42.3, 55.0, 63.9, 64.0, 65.0, 68.9,

71.9, 102.8, 177.9, 178.3. IR (neat, cm^ꢀ1) 2936, 1730,

1472, 1362, 1285, 1179, 1157, 839. LRMS (EI(+)) m/z

579 ([MꢀOMe]⁺), 578 ([MꢀMeOH]⁺), 521 ([Mꢀt-

BuꢀMeOH]⁺), 477, 451, 419, 159 (bp). HRMS (EI(+))

calcd for C₂₇H₅₁O₉SSi ([MꢀOMe]⁺) 579.3023, found

579.3044.

Compound 13b was also synthesized similarly (78%

yield) as a colorless oil.

3.3.2. 3-[(2S,3R,4R,5S,6S)-2-Bromomethyl-5-(tert-butyl-

dimethylsilyloxy)-6-methoxy-3-pivaloyloxymethyltetra-

23

D

hydropyran-4-yl]propyl pivalate (13b). ½aꢂ +32.9ꢁ (c 0.5,

1

CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.06 (3H,

s), 0.07 (3H, s), 0.89 (9H, s), 1.20 (9H, s), 1.20 (9H, s),

1.12–1.32 (1H, m), 1.53–1.66 (1H, m), 1.69–1.96 (3H,

m), 2.45 (1H, m), 3.39 (3H, s), 3.45 (1H, dd, J = 7.3,

11.0 Hz), 3.60 (1H, dd, J = 3.0, 11.0 Hz), 3.62 (1H, dd,

J = 2.6, 4.4 Hz), 3.90 (1H, ddd, J = 3.0, 7.3, 8.7 Hz),

3.99 (1H, dd, J = 7.2, 11.6 Hz), 4.02–4.12 (3H, m),

4.48 (1H, d, J = 2.6 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ4.8, ꢀ4.5, 18.1, 22.4, 25.8, 27.1, 27.2, 27.2,

35.0, 36.4, 38.8, 40.6, 55.3, 62.8, 64.3, 68.1, 69.2, 103.2,

178.0, 178.4. IR (neat, cm^ꢀ1) 2932, 1732, 1480, 1285,

1157, 1111, 1036, 837, 776. LRMS (EI(+)) m/z 594

(M(⁷⁹Br)⁺), 563 ([M(⁷⁹Br)ꢀOMe]⁺), 537 ([M(⁷⁹Br)ꢀt-

Bu]⁺), 505 ([Mꢀt-BuꢀMeOH]⁺), 461, 435, 353, 159

Compound 12b was also synthesized similarly (86%) as a

colorless oil.

3.2.2. 3-[(2S,3R,4R,5S,6S)-5-(tert-Butyldimethylsilyl-

oxy)-2-methanesulfonyloxymethyl-6-methoxy-3-pivaloyl-

oxymethyltetrahydropyran-4-yl]propyl pivalate (12b).

23

D

½aꢂ +38.9ꢁ (c 0.8, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (6H, s), 0.88 (9H, s), 1.20 (9H, s), 1.20 (9H,

s), 1.15–1.32 (1H, m), 1.50–1.57 (1H, m), 1.71–1.94 (3H,

m), 2.50 (1H, m), 3.10 (3H, s), 3.34 (3H, s), 3.67 (1H, dd,

J = 2.0, 3.6 Hz), 3.92 (1H, ddd, J = 2.5, 5.7, 9.5 Hz),

3.97–4.10 (4H, m), 4.25 (1H, dd, J = 5.5, 11.6 Hz),

3012

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

(bp). HRMS (EI(+)) calcd for C₂₇H₅₁⁷⁹BrO₇Si

(M(⁷⁹Br)⁺) 594.2587, found 594.2609.

perature for 13 h. The reaction mixture was quenched by

the addition of water (20 mL), extracted with AcOEt

(30 mL), and the organic layers were combined, washed

with brine (20 mL), dried (Na₂SO₄), and concentrated.

Puriﬁcation by silica gel column chromatography (hex-

ane/AcOEt (10:1)) gave the tosylate (914.4 mg, 95%) as

a colorless oil.

3.3.3. Reductive ring opening by Zn–NaBH₃CN. A mix-

ture of bromide 13a (1.01 g, 1.70 mmol), Zn dust

(2.59 g, 39.6 mmol), NaBH₃CN (802.7 mg, 12.8 mmol)

in 1-propanol (6 mL)–H₂O (0.6 mL) was stirred at

95 ꢁC for 4 h. After cooled to room temperature, satu-

rated aqueous NH₄Cl solution (20 mL) was added,

and the excess Zn dust was removed by decantation.

The liquid was extracted with AcOEt (2· 20 mL) and

the organic layers were combined, washed with brine

(20 mL), dried (Na₂SO₄), and concentrated. Puriﬁcation

by silica gel column chromatography (hexane/AcOEt

(15:2)) gave the alcohol 14a (730.9 mg, 88%) as a color-

less oil.

3.3.7. (4R,5S)-4-[(S)-1-(tert-Butyldimethylsilyloxy)-2-(4-

toluenesulfonyloxy)ethyl]-5-(pivaloyloxymethyl)hept-6-enyl

22

D

pivalate. ½aꢂ ꢀ3.8ꢁ (c 1.1, CHCl₃). ¹H NMR (400 MHz,

CDCl₃, ppm) d 0.00 (3H, s), 0.02 (3H, s), 0.83 (9H, s),

1.17 (9H, s), 1.18 (9H, s), 1.26–1.37 (1H, m), 1.40–1.73

(4H, m), 2.40–2.51 (1H, m), 2.46 (3H, s), 3.90 (1H, dd,

J = 6.2, 9.8 Hz), 3.92–4.01 (4H, m), 4.03 (1H, dd, J = 6.8,

11.2 Hz), 4.08 (1H, dd, J = 4.8, 11.2 Hz), 5.01–5.08 (1H,

m), 5.10 (1H, dd, J = 1.6, 10.4 Hz), 5.60 (1H, ddd,

J = 9.0, 10.4, 17.2 Hz), 7.37 (2H, m), 7.78 (2H, m). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ4.6, ꢀ4.0, 18.1, 21.7,

23.0, 25.9, 27.2, 27.7, 38.7, 38.8, 41.3, 44.5, 64.3, 65.3,

70.8, 71.3, 117.7, 127.9, 129.8, 132.8, 137.8, 144.9, 178.1,

178.3. IR (neat, cm^ꢀ1) 2930, 1730, 1480, 1370, 1285,

1179, 1159, 1049, 982, 833. LRMS (EI(+)) m/z 625

([MꢀMe]⁺), 583 ([Mꢀt-Bu]⁺), 411, 353, 329, 309, 229,

159, 133 (bp). HRMS (EI(+)) calcd for C₃₂H₅₃O₈SSi

([MꢀMe]⁺) 625.3230, found 625.3249.

3.3.4. (4R,5S)-4-[(S)-1-(tert-Butyldimethylsilyloxy)-2-hydroxy-

19

D

ethyl]-5-(pivaloyloxymethyl)-hept-6-enyl pivalate (14a). ½aꢂ

ꢀ4.5ꢁ (c 1.7, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.08 (3H, s), 0.09 (3H, s), 0.90 (9H, s), 1.18 (9H,

s), 1.19 (9H, s), 1.32–1.45 (1H, m), 1.46–1.58 (1H, m),

1.60–1.80 (4H, m), 2.55 (1H, m), 3.52 (1H, dd, J = 5.4,

11.2 Hz), 3.62 (1H, dd, J = 5.4, 11.2 Hz), 3.88 (1H, dt,

J = 3.5, 5.4 Hz), 4.02 (1H, dt, J = 10.8, 6.4 Hz), 4.05

(1H, dt, J = 10.8, 6.4 Hz), 4.08 (1H, dd, J = 7.6,

11.0 Hz), 4.15 (1H, dd, J = 5.2, 11.0 Hz), 5.04–5.16 (2H,

m), 5.72 (1H, ddd, J = 8.6, 10.4, 17.2 Hz). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ4.3, ꢀ3.9, 18.2, 23.5, 26.0,

27.3, 28.0, 38.8, 38.8, 41.5, 44.4, 64.4, 65.1, 65.2, 73.8,

117.2, 138.1, 178.3, 178.5. IR (neat, cm^ꢀ1) 3521, 2934,

1730, 1480, 1287, 1159, 1049, 837, 776. LRMS (EI(+))

m/z 455 ([MꢀCH₂OH]⁺), 429 ([Mꢀt-Bu]⁺), 353, 159

(bp). HRMS (EI(+)) calcd for C₂₅H₄₇O₅Si

([MꢀCH₂OH]⁺) 455.3193, found 455.3174.

Under an Ar atmosphere, to a solution of the tosylate

prepared above (914.4 mg, 1.43 mmol) in THF (7 mL)

was added TBAF (1 M in THF, 3.6 mL, 3.6 mmol)

and stirred at 0 ꢁC for 6 h. The reaction was quenched

by the addition of saturated aqueous NH₄Cl solution

(20 mL), and the mixture was extracted with AcOEt

(2· 20 mL). The combined organic layers were washed

with brine (20 mL), dried (Na₂SO₄), and concentrated.

Puriﬁcation by silica gel column chromatography (hex-

ane/AcOEt (10:1)) gave the epoxide 15a (462.1 mg,

91%) as a colorless oil.

Compound 14b was also synthesized similarly (quant.)

as a colorless oil.

3.3.5. (4R,5R)-4-[(S)-1-(tert-Butyldimethylsilyloxy)-2-

hydroxyethyl]-5-(pivaloyloxymethyl)-hept-6-enyl pivalate

(14b). ½aꢂ +13.8ꢁ (c 1.1, CHCl₃). H NMR (400 MHz,

3.3.8. (4R,5S)-4-[(S)-Oxiranyl]-5-(pivaloyloxymethyl)-

18

hept-6-enyl pivalate (15a). ½aꢂ ꢀ20.5ꢁ (c 1.0, CHCl₃).

D

20

D

¹H NMR (400 MHz, CDCl₃, ppm) d 1.18 (9H, s), 1.20

(9H, s), 1.18–1.30 (1H, m), 1.52–1.69 (2H, m), 1.70–1.82

(2H, m), 2.49 (1H, dd, J = 3.6, 4.4 Hz), 2.58 (1H, m),

2.74–2.81 (2H, m), 4.01–4.11 (3H, m), 4.15 (1H, dd,

J = 7.6, 11.0 Hz), 5.10–5.20 (2H, m), 5.70 (1H, ddd,

J = 9.3, 10.3, 17.1 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d 26.2, 27.0, 27.2, 27.2, 38.7, 38.7, 42.2, 45.1, 47.0,

53.6, 64.2, 64.8, 118.3, 135.1, 178.0, 178.3. IR (neat,

cm^ꢀ1) 2975, 1730, 1482, 1285, 1159, 1038, 924. LRMS

(EI(+)) m/z 354 (M⁺), 324 ([MꢀCH₂O]⁺), 311, 252, 167,

150, 120, 85, 57 (t-Bu, bp). HRMS (EI(+)) calcd for

C₂₀H₃₄O₅(M⁺) 354.2406, found 354.2399.

1

CDCl₃, ppm) d 0.10 (6H, s), 0.91 (9H, s), 1.18 (9H, s),

1.19 (9H, s), 1.30–1.52 (2H, m), 1.67–1.80 (4H, m), 2.59

(1H, m), 3.55 (1H, dd, J = 4.0, 11.2 Hz), 3.67 (1H, dd,

J = 6.0, 11.2 Hz), 3.81 (1H, m), 4.00 (1H, dt, J = 11.1,

6.6 Hz), 4.03 (1H, dt, J = 11.1, 6.6 Hz), 4.05 (1H, dd,

J = 8.4, 11.1 Hz), 4.12 (1H, dd, J = 5.4, 11.1 Hz), 5.04–

5.11 (2H, m), 5.13 (1H, dd, J = 1.8, 10.1 Hz), 5.63 (1H,

ddd, J = 9.3, 10.1, 16.9 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ4.4, ꢀ4.2, 18.2, 23.8, 25.9, 27.3, 28.3, 38.3, 38.8,

41.5, 44.2, 64.0, 64.3, 65.6, 74.5, 118.1, 137.0, 178.2, 178.4.

IR (neat, cm^ꢀ1) 3542, 2934, 1730, 1482, 1287, 1256, 1161,

1049, 837, 777. LRMS (EI(+)) m/z 455 ([MꢀCH₂OH]⁺),

429 ([Mꢀt-Bu]⁺), 353, 327, 159, 117 (bp). HRMS

(EI(+)) calcd for C₂₅H₄₇O₅Si ([MꢀCH₂OH]⁺) 455.3193,

found 455.3199.

Synthesis of the epoxide from 14b was also carried out

similarly (87% for two steps).

3.3.9. (4R,5R)-4-[(S)-1-(tert-Butyldimethylsilyloxy)-2-(4-

toluenesulfonyloxy)ethyl]-5-(pivaloyloxymethyl)hept-6-enyl

3.3.6. Tosylation of the alcohol 14a,b followed by base

treatment. Under an Ar atmosphere, a mixture of alcohol

14a (730.6 mg, 1.50 mmol), Et₃N (630 lL, 4.52 mmol),

DMAP (170.4 mg, 1.39 mmol), TsCl (422.4 mg,

2.22 mmol) in CH₂Cl₂(7.5 mL) was stirred at room tem-

22

D

1

pivalate. A colorless oil, ½aꢂ +14.8ꢁ (c 1.3, CHCl₃). H

NMR (400 MHz, CDCl₃, ppm) d 0.00 (3H, s), 0.01

(3H, s), 0.81 (9H, s), 1.13 (9H, s), 1.15 (9H, s), 1.22–

1.32 (1H, m), 1.32–1.44 (1H, m), 1.48–1.66 (3H, m),

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3013

2.42 (3H, s), 2.52 (1H, m), 3.88–3.96 (6H, m), 3.99 (1H,

dd, J = 5.6, 11.2 Hz), 5.00 (1H, dd, J = 1.5, 17.1 Hz),

5.06 (1H, dd, J = 1.5, 10.2 Hz), 5.54 (1H, ddd, J = 9.6,

10.2, 17.1 Hz), 7.31 (2H, m), 7.74 (2H, m). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.3, 18.0, 21.6, 23.2,

25.7, 27.2, 27.7, 38.7, 42.1, 43.7, 64.0, 65.2, 71.3, 71.3,

118.3, 127.8, 129.7, 132.7, 136.8, 144.8, 178.0, 178.2. IR

(neat, cm^ꢀ1) 2934, 1730, 1480, 1368, 1285, 1179, 1157,

980, 837, 779. LRMS (EI(+)) m/z 625 ([MꢀMe]⁺), 583

([Mꢀt-Bu]⁺), 411, 353, 329, 309, 229 (bp), 159, 133.

HRMS (EI(+)) calcd for C₃₂H₅₃O₈SSi ([MꢀMe]⁺)

625.3230, found 625.3236.

ddd, J = 2.1, 6.5, 7.5 Hz), 5.01–5.21 (2H, m), 5.80 (1H,

ddd, J = 8.7, 10.5, 17.3 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d 21.3, 25.7, 31.8, 43.0, 49.2, 62.8, 63.1,

70.6, 72.0, 81.4, 117.4, 138.5. IR (neat, cm^ꢀ1) 3357,

3303, 3079, 2938, 2118, 1640, 1424, 1375, 1258, 1048,

916. LRMS (EI(+)) m/z 212 (M⁺), 211 ([MꢀH]⁺), 55

(bp). HRMS (EI(+)) calcd for C₁₂H₂₀O₃(M⁺)

212.1412, found 212.1405.

Under an Ar atmosphere, to a cooled (ꢀ78 ꢁC) solution

of the triol prepared as above (151.2 mg, 0.712 mmol)

and 2,6-lutidine (747 lL, 6.41 mmol) was added

TBSOTf (736 lL, 3.20 mmol) and stirred at the same

temperature for 1 h. The reaction was quenched by the

addition of saturated aqueous NaHCO₃solution

(10 mL), and the mixture was extracted with AcOEt

(20 mL). The organic layer was washed with brine

(20 mL), dried (Na₂SO₄), and concentrated. Puriﬁcation

by silica gel column chromatography (hexane/AcOEt

(50:1)) gave the TBS ether 16a (257.3 mg, 65%) as a col-

orless oil.

3.3.10. (4R,5R)-4-[(S)-Oxiranyl]-5-(pivaloyloxymethyl)-

19

D

hept-6-enyl pivalate (15b). A colorless oil, ½aꢂ +6.6ꢁ (c

1

1.0, CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 1.18

(9H, s), 1.20 (9H, s), 1.14–1.29 (1H, m), 1.46–1.58 (1H,

m), 1.71–1.80 (2H, m), 1.82–1.95 (1H, m), 2.48 (1H, dd,

J = 3.0, 4.6 Hz), 2.53 (1H, m), 2.76–2.84 (2H, m), 4.06

(2H, t, J = 6.4 Hz), 4.08 (1H, dd, J = 6.8, 11.1 Hz), 4.14

(1H, dd, J = 5.6, 11.1 Hz), 5.09–5.19 (2H, m), 5.67 (1H,

ddd, J = 9.1, 10.3, 16.9 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d 26.1, 26.5, 27.2, 27.2, 38.7, 38.8, 42.3,

45.5, 46.5, 54.6, 64.2, 64.7, 118.0, 136.2, 178.1, 178.3.

IR (neat, cm^ꢀ1) 2975, 1730, 1482, 1285, 1157, 1036,

922. LRMS (EI(+)) m/z 354 (M⁺), 324 ([MꢀCH₂O]⁺),

311, 252, 150, 137, 120, 57 (t-Bu, bp). HRMS (EI(+))

calcd for C₂₀H₃₄O₅(M⁺) 354.2406, found 354.2426.

3.3.13. (3S,4R,5R)-5-(tert-Butyldimethylsilyloxy)-3-(tert-

butyldimethylsilyloxymethyl)-4-[3-(tert-butyldimethylsi-

21

D

lyloxy)propyl]oct-1-en-7-yne (16a). ½aꢂ ꢀ14.0ꢁ (c 1.0,

1

CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.02 (6H,

s), 0.04 (3H, s), 0.04 (6H, s), 0.06 (3H, s), 0.87 (9H, s),

0.88 (9H, s), 0.89 (9H, s), 1.24–1.37 (1H, m), 1.48–1.74

(3H, m), 1.87 (1H, m), 1.95 (1H, t, J = 2.7 Hz), 2.27

(1H, m), 2.35 (1H, ddd, J = 2.7, 5.8, 16.8 Hz), 2.40 (1H,

ddd, J = 2.7, 7.9, 16.8 Hz), 3.59 (2H, t, J = 6.4 Hz), 3.65

(2H, dd, J = 5.6, 10.1 Hz), 3.68 (1H, dd, J = 5.0,

10.1 Hz), 4.00 (1H, ddd, J = 2.0, 5.8, 7.9 Hz), 4.99–5.10

(2H, m), 5.76 (1H, ddd, J = 9.1, 10.5, 17.1 Hz). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ5.2, ꢀ5.2, ꢀ5.2,

ꢀ4.3, ꢀ3.7, 18.2, 18.3, 18.4, 22.6, 26.0, 26.1, 32.3, 41.9,

48.1, 63.6, 64.9, 70.1, 72.0, 81.8, 116.0, 140.4. IR (neat,

cm^ꢀ1) 3316, 3075, 2930, 1472, 1254, 1102, 837, 776.

LRMS (EI(+)) m/z 554 (M⁺), 539 ([MꢀMe]⁺), 515

([MꢀC₃H₃]⁺), 497 ([Mꢀt-Bu]⁺), 457 ([Mꢀt-BuꢀHꢀ

C₃H₃]⁺), 422 ([MꢀTBSOH]⁺), 407 ([MꢀTBSOHꢀMe]⁺),

383 ([MꢀTBSOHꢀC₃H₃]⁺), 365 ([MꢀTBSOHꢀt-Bu]⁺),

291, 251, 233, 183, 147, 73 (bp). HRMS (EI(+)) calcd

for C₃₀H₆₂O₃Si₃(M⁺) 554.4007, found 554.3995.

3.3.11. Ethynylation followed by protection. Under an Ar

atmosphere, to a cooled (ꢀ78 ꢁC) solution of epoxide

15a (435.9 mg, 1.23 mmol) in THF (6 mL) was added

a solution of lithium TMS-acetylide (0.44 M in THF–

hexane, prepared from TMS-acetylene and n-BuLi,

8.4 mL, 3.70 mmol) and BF₃ÆOEt₂(234 lL, 185 mmol),

and the mixture was stirred at the same temperature

for 6 h. The reaction was quenched by the addition of

saturated aqueous NH₄Cl solution (30 mL), and the

mixture was extracted with AcOEt (2· 20 mL). The

combined organic layers were washed with brine

(20 mL), dried (Na₂SO₄) and concentrated. The crude

residue was dissolved in MeOH (5 mL) and NaOMe

(28% in MeOH, 1.2 mL, 6.2 mmol) was added. The mix-

ture was stirred at 0 ꢁC for 5 min, warmed at 40 ꢁC, and

stirred for 11.5 h. The reaction was quenched by the

addition of saturated aqueous NH₄Cl (10 mL), and the

mixture was extracted with AcOEt (20 mL). The organic

layer was washed with water (10 mL), and the aqueous

layers were combined, saturated with NaCl, and ex-

tracted with AcOEt (5· 10 mL). The combined organic

layers were washed with brine (20 mL), dried (Na₂SO₄)

and concentrated. Puriﬁcation by silica gel column chro-

matography (AcOEt) gave the triol (151.2 mg, 58% for

two steps) as a colorless oil.

The synthesis of 16b was also carried out similarly (58%

for three steps).

3.3.14. (4R,5R)-4-[(R)-1-(Hydroxymethyl)allyl]oct-7-yne-

21

D

1

1,5-diol. A colorless oil, ½aꢂ +3.8ꢁ (c 0.5, CHCl₃). H

NMR (400 MHz, CDCl₃, ppm) d 1.46–1.73 (4H, m),

1.84 (1H, m), 2.07 (1H, t, J = 2.7 Hz), 2.40 (1H, ddd,

J = 2.7, 6.2, 12.7 Hz), 2.45 (1H, m), 2.49 (1H, ddd,

J = 2.7, 7.4, 12.7 Hz), 3.40 (3H, br s), 3.65 (2H, m),

3.68 (1H, dd, J = 5.6, 11.2 Hz), 3.73 (1H, dd, J = 5.2,

11.2 Hz), 3.96 (1H, ddd, J = 3.2, 6.2, 7.4 Hz), 5.15–

5.22 (2H, m), 5.83 (1H, ddd, J = 8.1, 9.9, 17.9 Hz). ¹³C

NMR (100 MHz, CDCl₃, ppm) d 22.2, 24.8, 31.3, 43.4,

46.2, 62.5, 62.6, 70.2, 70.6, 81.4, 117.3, 137.8. IR (neat,

cm^ꢀ1) 3332, 3301, 3077, 2936, 2118, 1640, 1424, 1256,

1053, 918. LRMS (EI(+)) m/z 212 (M⁺), 211

([MꢀH]⁺), 57 (bp). HRMS (EI(+)) calcd for C₁₂H₂₀O₃

(M⁺) 212.1412, found 212.1414.

3.3.12. (4R,5R)-4-[(S)-1-(Hydroxymethyl)allyl]oct-7-yne-

20

D

1,5-diol. ½aꢂ

ꢀ21.3ꢁ (c 0.7, CHCl₃). ¹H NMR

(400 MHz, CDCl₃, ppm) d 1.38–1.47 (1H, m), 1.53–

1.76 (3H, m), 1.76–1.82 (1H, m), 2.06 (1H, t,

J = 2.8 Hz), 2.39 (1H, ddd, J = 2.8, 6.5, 16.7 Hz), 2.46

(1H, m), 2.51 (1H, ddd, J = 2.8, 7.5, 16.7 Hz), 2.76

(3H, br s), 3.64 (1H, dd, J = 6.6, 10.6 Hz), 3.64 (2H, t,

J = 6.6 Hz), 3.72 (1H, dd, J = 7.0, 10.6 Hz), 3.96 (1H,

3014

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3.3.15. (3R,4R,5R)-5-(tert-Butyldimethylsilyloxy)-3-(tert-

butyldimethylsilyloxymethyl)-4-[3-(tert-butyldimethylsi-

3.4.1. The 1a-hydroxymethylated analogue (2b) was also

24

D

prepared similarly (53%) as a white powder. ½aꢂ +41.3ꢁ

21

1

lyloxy)propyl]oct-1-en-7-yne (16b). A colorless oil, ½aꢂ

(c 1.5, CHCl₃). H NMR (600 MHz, CDCl₃, ppm) d

0.51 (3H, s), 0.93 (3H, d, J = 6.6 Hz), 1.01–1.09 (1H,

m), 1.21 (9H, s), 1.17–1.64 (11H, m), 1.64–1.76 (4H,

m), 1.81–2.03 (7H, m), 2.25 (1H, dd, J = 9.1, 13.3 Hz),

2.59 (2H, br s), 2.64 (1H, dd, J = 4.5, 13.3 Hz), 2.62–

2.69 (1H, m), 2.78–2.84 (1H, m), 3.51 (1H, dd, J = 9.1,

10.6 Hz), 3.64–3.70 (2H, m), 3.71 (1H, apparent dt,

J = 4.5, 8.4 Hz), 4.99 (1H, d, J = 1.9 Hz), 5.09 (1H, d,

J = 1.9 Hz), 5.95 (1H, d, J = 11.3 Hz), 6.31 (1H, d,

J = 11.3 Hz). ¹³C NMR (150 MHz, CDCl₃, ppm) d

11.9, 18.8, 20.8, 22.2, 23.5, 23.9, 27.7, 29.1, 29.2, 29.3,

30.0, 36.1, 36.4, 40.5, 44.4, 44.9, 45.7, 45.9, 47.6, 56.3,

56.5, 60.3, 62.5, 70.8, 71.1, 114.3, 116.7, 123.1, 134.4,

143.4, 145.6. IR (ﬁlm, cm^ꢀ1) 3355, 2944, 1649, 1466,

1377, 1032, 909, 735. LRMS (EI(+)) m/z 488 (M⁺),

470 ([MꢀH₂O]⁺), 452 ([Mꢀ2·H₂O]⁺), 434 ([Mꢀ3·

H₂O]⁺), 422 ([MꢀH₂OꢀCH₂OHꢀOH]⁺), 157, 55 (bp).

HRMS (EI(+)) calcd for C₃₁H₅₂O₄(M⁺) 488.3866,

found 488.3865.

D

+12.6ꢁ (c 1.3, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.02 (6H, s), 0.04 (6H, s), 0.06 (3H, s), 0.10 (3H,

s), 0.88 (9H, s), 0.89 (18H, s), 1.24–1.46 (2H, m), 1.47–

1.67 (2H, m), 1.86 (1H, m), 1.92 (1H, t, J = 2.7 Hz), 2.37

(2H, dd, J = 2.7, 6.2 Hz), 2.42 (1H, m), 3.55 (1H, dd,

J = 4.8, 9.8 Hz), 3.65 (2H, t, J = 6.4 Hz), 3.62 (1H, dd,

J = 5.4, 9.8 Hz), 3.95 (1H, dt, J = 3.9, 6.2 Hz), 5.01–5.09

(2H, m), 5.73 (1H, ddd, J = 9.4, 9.4, 17.7 Hz). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ5.3, ꢀ5.2, ꢀ5.2, ꢀ4.5,

ꢀ4.0, 18.2, 18.4, 18.4, 23.0, 25.0, 26.0, 26.0, 26.0, 32.3,

42.2, 47.0, 63.6, 65.0, 70.0, 72.5, 82.3, 116.6, 139.0. IR

(neat, cm^ꢀ1) 3316, 3071, 2930, 1472, 1254, 1100, 835,

776. LRMS (EI(+)) m/z 554 (M⁺), 539 ([MꢀMe]⁺), 515

([MꢀC₃H₃]⁺), 497 ([Mꢀt-Bu]⁺), 457 ([Mꢀt-BuꢀHꢀ

C₃H₃]⁺), 422 ([MꢀTBSOH]⁺), 407 ([MꢀTBSOHꢀMe]⁺),

383 ([MꢀTBSOHꢀC₃H₃]⁺), 365 ([MꢀTBSOHꢀt-Bu]⁺),

291, 251, 233, 183, 147, 73 (bp). HRMS (EI(+)) calcd

for C₃₀H₆₂O₃Si₃(M⁺) 554.4007, found 554.4001.

3.4. Synthesis of 1b-(hydroxymethyl)-2a-(3-hydroxypro-

pyl)-25-hydroxyvitamin D₃(2a)

3.5. Synthesis of 2a-(3-hydroxypropyl)-1-unsubstituted

analogue (3)

Under an Ar atmosphere, a mixture of A-ring enyne 16a

(52.8 mg, 95.1 lmol), CD-ring bromooleﬁn 6¹²(38.8 mg,

0.109 mmol), Pd(PPh₃)₄(56.6 mg, 49.0 lmol) in PhMe

(300 lL)-Et₃N (300 lL) was stirred at 90 ꢁC for 2 h.

After cooled to room temperature, the mixture was di-

luted with AcOEt, ﬁltered through Celite, washed with

AcOEt, and the ﬁltrate was concentrated. The residue

was partially puriﬁed with silica gel column chromatog-

raphy (hexane/AcOEt (50:1)). The residue was diluted

with THF (500 lL), and HFÆpyridine (100 lL) was

added. After stirred at room temperature for 1 h, the

reaction was quenched by the addition of water

(1 mL), and the mixture was extracted with AcOEt (2·

2 mL). The combined organic layers were washed with

saturated aqueous NaHCO₃solution (5 mL), brine

(5 mL), dried (Na₂SO₄), and concentrated. Puriﬁcation

by silica gel column chromatography (AcOEt) gave the

product (17.5 mg, 38%) as a white powder.

3.5.1. Methyl 4,6-O-Benzylidene-3-C-{3-(tert-butyldi-

phenylsilyloxy)propyl}-3-deoxy-a-^D-altropyranoside. Un-

der an Ar atmosphere, to a cold (0 ꢁC) solution of

methyl 4,6-O-benzylidene-3-deoxy-3-C-(3-hydroxypro-

pyl)-a-^D-altropyranoside (prepared from sugar epoxide

7 as in the case of 2a,b, 2.2 g, 6.78 mmol) in CH₂Cl₂

(68 mL) were added Et₃N (2.6 mL, 18.7 mmol),

TBDPSCl (2.1 mL, 8.1 mmol), and DMAP (82 mg,

0.68 mmol), and stirred at room temperature overnight.

The reaction mixture was cooled (0 ꢁC), and saturated

aqueous NH₄Cl solution (100 mL) was added. The mix-

ture was extracted with AcOEt (300 mL), and the organic

layer was washed with brine (50 mL), dried (MgSO₄), and

concentrated. Puriﬁcation by silica gel column chroma-

tography (hexane/AcOEt (9:1 to 5:1)) gave the TBDPS

ether (3.58 g, 94%) as a colorless oil.

22

D

½aꢂ +57.8ꢁ (c 1.7, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 1.05 (9H, s), 1.56–1.65 (1H, m), 1.70–1.77 (1H, m),

1.80–1.87 (2H, m), 3.35 (3H, s), 3.69 (2H, t, J = 6.4 Hz),

3.77 (1H, t, J = 10.0 Hz), 3.91 (1H, br s), 3.98 (1H, ddd,

J = 4.7, 10.0, 14.9 Hz), 4.09 (1H, dd, J = 4.7, 10.0 Hz),

4.28 (1H, dd, J = 4.9, 10.3 Hz), 4.58 (1H, s), 5.58 (1H,

s), 7.33–7.43 (9H, m), 7.47–7.49 (2H, m), 7.66–7.69 (4H,

m). ¹³C NMR (100 MHz, CDCl₃, ppm) d 19.3, 20.9,

26.9, 31.4, 42.7, 55.2, 59.5, 64.0, 69.6, 70.3, 102.0, 102.2,

126.2, 127.5, 128.2, 128.8, 129.4, 134.0, 135.5, 135.5,

137.7. IR (neat, cm^ꢀ1) 3331, 2932, 2892, 2859, 1612,

1590, 1138, 1107, 1053, 1028, 700. LRMS (EI(+)) m/z

562 (M⁺), 473 ([Mꢀt-BuꢀMeOH]⁺), 367, 295. HRMS

(EI(+)) calcd for C₃₃H₄₂O₆Si (M⁺) 562.2751, found

562.2754.

22

D

½aꢂ ꢀ81.8ꢁ (c 0.2, CHCl₃). ¹H NMR (600 MHz, CDCl₃,

ppm) d 0.55 (3H, s), 0.94 (3H, d, J = 6.6 Hz), 1.02–1.10

(1H, m), 1.22 (6H, s), 1.17–1.72 (22H, m), 1.83–1.92

(2H, m), 1.95–2.03 (2H, m), 2.28 (1H, dd, J = 3.6,

14.4 Hz), 2.38 (1H, dt, J = 1.2, 5.4 Hz), 2.65 (1H, d,

J = 14.4 Hz), 2.82 (1H, dd, J = 4.2, 12.0 Hz), 3.66 (2H,

t, J = 6.3 Hz), 3.70 (1H, dd, J = 6.0, 11.1 Hz), 3.73 (1H,

dd, J = 6.0, 11.1 Hz), 3.85 (1H, apparent q, J = 3.2 Hz),

5.05 (1H, d, J = 3.0 Hz), 5.16 (1H, d, J = 3.0 Hz), 6.02

(1H, d, J = 11.4 Hz), 6.30 (1H, d, J = 11.4 Hz). ¹³C

NMR (150 MHz, CDCl₃, ppm) d 11.9, 18.8, 20.8, 22.3,

23.7, 27.6, 28.7, 29.2, 29.2, 29.4, 30.7, 36.1, 36.4, 40.5,

41.2, 44.1, 44.4, 46.0, 50.7, 56.3, 56.6, 62.8, 66.8, 71.1,

71.2, 116.1, 116.8, 123.6. IR (ﬁlm, cm^ꢀ1) 3360, 2942,

1653, 1470, 1377, 1042, 756. LRMS (EI(+)) m/z 488

(M⁺), 470 ([MꢀH₂O]⁺), 458 ([MꢀCH₂O]⁺), 452

([Mꢀ2·H₂O]⁺), 440 ([MꢀCH₂OꢀH₂O]⁺), 421 ([Mꢀ2·

H₂OꢀCH₂OH]⁺), 363, 59 (bp). HRMS (EI(+)) calcd for

C₃₁H₅₂O₄(M⁺) 488.3866, found 488.3850.

3.5.2. Methyl 4,6-O-Benzylidene-2-O-(tert-butyldimethyl-

silyl)-3-C-{3-(tert-butyldiphenylsilyloxy)propyl}-3-deoxy-

a-^D-altropyranoside (17). Under an Ar atmosphere, to a

cold (0 ꢁC) solution of the TBDPS ether prepared as

above (3.5 g, 6.21 mmol) in CH₂Cl₂(62 mL) were added

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3015

2,6-lutidine (2.2 mL, 18.6 mmol) and TBSOTf (2.2 mL,

9.3 mmol), and stirred at 0 ꢁC for 30 min. The reaction

was quenched by the addition of water (50 mL) and ex-

tracted with AcOEt (300 mL). The organic extract was

washed with water (50 mL), saturated aqueous NH₄Cl

solution (50 mL), brine (50 mL), dried (MgSO₄), and

concentrated. Puriﬁcation by silica gel column chroma-

tography (hexane/AcOEt (50:1)) gave the product

(4.06 g, 96%) as a colorless oil.

(15 mL). The layers were separated, and the organic

layer was washed with brine (15 mL), dried (MgSO₄),

and concentrated. Puriﬁcation by silica gel column chro-

matography (hexane/AcOEt (20:1)) gave the product 18

(403 mg, 93%) as a colorless oil.

22

D

½aꢂ +12.0ꢁ (c 0.2, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (6H, s), 0.89 (9H, s), 1.04 (9H, s), 1.50–1.62

(3H, m), 1.67–1.75 (2H, m), 2.23 (1H, br s), 3.30–3.37

(5H, m), 3.63–3.67 (3H, m), 3.74 (1H, dd, J = 5.3,

12.0 Hz), 3.95 (1H, br s), 4.39 (1H, d, J = 2.7 Hz),

7.17–7.40 (15H, m), 7.46–7.48 (6H, m), 7.66–7.68 (4H,

m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.7, ꢀ4.5,

18.1, 19.2, 21.2, 25.9, 26.9, 30.9, 43.3, 55.1, 64.3, 64.9,

67.5, 71.1, 71.7, 103.7, 127.0, 127.5, 127.8, 127.8,

128.6, 129.4, 133.9, 135.5, 143.7. IR (neat, cm^ꢀ1) 3456,

3069, 3032, 2934, 2893, 2859, 1597, 1489, 1472, 1449,

1109, 1046, 767, 704. LRMS (FAB(+), NBA) m/z 853

([M+Na]⁺). HRMS (FAB(+), NBA) calcd for

C₅₁H₆₆O₆Si₂Na ([M+Na]⁺) 853.4249, found 853.4272.

22

D

½aꢂ +33.4ꢁ (c 3.9, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.07 (6H, s), 0.91 (9H, s), 1.04 (9H, s), 1.58–1.62

(1H, m), 1.69–1.84 (3H, m), 2.02–2.04 (1H, m), 3.32

(3H, s), 3.68 (2H, t, J = 6.1 Hz), 3.76 (1H, dd, J = 10.0,

10.3 Hz), 3.87 (1H, m), 3.92 (1H, ddd, J = 5.0, 10.0,

14.9 Hz), 4.10 (1H, dd, J = 5.0, 10.3 Hz), 4.25 (1H, dd,

J = 5.0, 10.1 Hz), 4.44 (1H, s), 5.59 (1H, s), 7.33–7.41

(9H, m), 7.47–7.49 (2H, m), 7.66–7.68 (4H, m). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ4.9, ꢀ4.8, 18.1, 19.3,

21.0, 25.9, 26.9, 31.6, 43.6, 55.0, 59.4, 64.1, 69.7, 70.7,

101.9, 102.7, 126.2, 127.5, 128.2, 128.8, 129.4, 134.1,

135.5, 135.5, 137.9. IR (neat, cm^ꢀ1) 2953, 2930, 2859,

1591, 1543, 1140, 1107, 1049, 1028, 1012, 700. LRMS

(EI(+)) m/z 437 ([MꢀTBDPS]⁺), 421([MꢀOTBDPS]⁺),

363, 199, 183. HRMS calcd for C₂₃H₃₇O₆Si

([MꢀTBDPS]⁺) 437.2356, found 437.2386.

3.5.5. O-[(2R,3S,4R,5R,6S)-5-(tert-Butyldimethylsilyl-

oxy)-4-{3-(tert-butyldiphenylsilyloxy)propyl}-6-methoxy-

2-{(triphenylmethyloxy)methyl}tetrahydropyran-3-yl] S-

methyl dithiocarbonate. Under an Ar atmosphere, to a

solution of 18 (108 mg, 0.13 mmol) in Et₂O (500 lL)

were added CS₂(23 lL, 0.39 mmol) and NaH (60% in

oil, 260 mg, 6.5 mmol), and stirred at room temperature

for 1 h. MeI (80 lL, 1.3 mmol) was added and the mix-

ture was stirred at room temperature for 4 h. The reac-

tion mixture was cooled to 0 ꢁC, diluted with Et₂O

(100 mL), and washed with saturated aqueous NH₄Cl

solution (10 mL). The organic layer was washed with

brine (10 mL), dried (MgSO₄), and concentrated. Puriﬁ-

cation by silica gel column chromatography (hexane/

AcOEt (30:1)) gave the xanthate (111 mg, 93%) as a

white amorphous solid.

3.5.3. Methyl 2-O-(tert-Butyldimethylsilyl)-3-C-{3-(tert-

butyldiphenylsilyloxy)propyl}-3-deoxy-a-^D-altropyrano-

side. Li metal (83 mg, 2.59 mmol) was dissolved in liquid

NH₃(30 mL) at ꢀ78 ꢁC, and to this was added a solu-

tion of 17 (500 mg, 0.74 mmol) in THF (9 mL). After

stirred at the same temperature for 15 min, solid NH₄Cl

was added. Excess NH₃was volatized, and the residue

was partitioned between CH₂Cl₂(300 mL) and water

(30 mL). The layers were separated, and the organic

layer was washed with brine (30 mL), dried (MgSO₄),

and concentrated. Puriﬁcation by silica gel column chro-

matography (hexane/AcOEt (9:1 to 4:1)) gave the diol

(411 mg, 95%) as a colorless oil.

21

D

½aꢂ +43.5ꢁ (c 0.5, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.08 (6H, s), 0.92 (9H, s), 1.02 (9H, s), 1.32–1.58

(3H, m), 1.77–1.86 (1H, m), 2.17–2.23 (1H, m), 2.39 (3H,

s), 3.23 (1H, dd, J = 5.5, 10.0 Hz), 3.36 (1H, dd, J = 3.5,

10.0 Hz), 3.39 (3H, s), 3.60 (2H, t, J = 6.1 Hz), 3.70 (1H,

dd, J = 3.4, 6.9 Hz), 4.01 (1H, dt, J = 3.5, 5.5 Hz), 4.49

(1H, d, J = 3.4 Hz), 6.08 (1H, dt, J = 4.4, 6.4 Hz),

7.19–7.23 (3H, m), 7.25–7.29 (6H, m), 7.32–7.39 (6H,

m), 7.47–7.49 (6H, m), 7.62–7.65 (4H, m). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.5, 18.1, 18.1, 18.7,

19.2, 22.1, 25.9, 26.8, 30.7, 41.8, 55.3, 63.3, 64.0, 71.8,

78.1, 86.6, 103.3, 126.9, 127.6, 127.8, 128.8, 129.5,

134.0, 135.6, 143.9, 214.3. IR (ﬁlm, cm^ꢀ1) 2953, 2930,

2885, 2867, 1651, 1581, 1462, 1447, 1428, 1109, 1059,

750, 700. LRMS (FAB(+), NBA) m/z 943 ([M+Na]⁺).

HRMS (FAB(+), NBA) calcd for C₅₃H₆₈O₆Si₂S₂Na

([M+Na]⁺) 943.3894, found 943.3902.

22

D

½aꢂ +34.6ꢁ (c 2.0, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (6H, s), 0.88 (9H, s), 1.05 (9H, s), 1.56–1.71

(4H, m), 1.73–1.77 (1H, m), 2.04–2.07 (1H, m), 3.34

(3H, s), 3.67–3.71 (4H, m), 3.75 (1H, dd, J = 5.4,

11.2 Hz), 3.81 (1H, dd, J = 3.9, 11.2 Hz), 4.02 (1H, br s),

4.42 (1H, d, J = 1.7 Hz), 7.26–7.44 (6H, m), 7.66–7.68

(4H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8,

ꢀ4.7, 18.1, 19.2, 20.8, 25.9, 26.9, 30.9, 44.1, 55.1, 63.7,

64.2, 66.4, 70.9, 71.6, 103.6, 127.5, 129.5, 133.8, 135.5.

IR (neat, cm^ꢀ1) 3430, 3073, 2955, 2930, 2899, 2859,

1472, 1427, 704. LRMS (EI(+)) m/z 349 ([MꢀTBDPS]⁺),

289, 199, 181. HRMS calcd for C₁₆H₃₃O₆Si

([MꢀTBDPS]⁺) 349.2046, found 349.2041.

3.5.4. Methyl 2-O-(tert-Butyldimethylsilyl)-3-C-{3-(tert-

butyldiphenylsilyloxy)propyl}-3-deoxy-6-O-(triphenyl-

methyl)-a-^D-altropyranoside (18). To a solution of the

diol prepared as above (322 mg, 0.54 mmol) in DMF

(3 mL) were added TrCl (452 mg, 1.62 mmol) and

DMAP (198 mg, 1.62 mmol), and stirred at 75 ꢁC over-

night. The reaction mixture was cooled to room temper-

ature, and partitioned between Et₂O (15 mL) and water

3.5.6. Methyl 2-O-(tert-Butyldimethylsilyl)-3-C-{3-(tert-

butyldiphenylsilyloxy)propyl}-3,4-dideoxy-6-O-(triphen-

ylmethyl)-a-^D-altropyranoside (19). To a solution of

xanthate prepared as above (347 mg, 0.38 mmol) in ben-

zene (1.3 mL) were added n-Bu₃SnH (511 lL, 1.9 mmol)

and AIBN (37 mg, 0.23 mmol), and stirred at 80 ꢁC for

7 h. The reaction mixture was cooled to room tempera-

3016

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

ture, and the solvent was removed under reduced pres-

sure. The residue was puriﬁed by silica gel column chro-

matography (hexane/AcOEt (50:1)) gave the product 19

(309 mg, quant.) as a colorless oil.

AcOEt (4:1)) gave the mesylate (220 mg, 97%) as a col-

orless oil.

22

D

½aꢂ +22.1ꢁ (c 0.8, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (3H, s), 0.07 (3H, s), 0.88 (9H, s), 1.05 (9H,

s), 1.19–1.22 (1H, m), 1.46–1.57 (3H, m), 1.69–1.75 (1H,

m), 1.89–1.94 (1H, m), 3.07 (3H, s), 3.32 (3H, s), 3.43

(3H, br s), 3.98–4.04 (1H, m), 4.19 (1H, dd, J = 6.5,

11.0 Hz), 4.27 (1H, dd, J = 2.9, 11.0 Hz), 4.44 (1H, s),

7.36–7.43 (6H, m), 7.65–7.67 (4H, m). ¹³C NMR

(150 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.7, 18.1, 19.3, 25.8,

25.9, 26.7, 26.9, 30.8, 37.8, 55.1, 63.4, 63.9, 70.4, 72.5,

103.0, 127.5, 129.4, 133.9, 135.5. IR (neat, cm^ꢀ1) 2953,

2932, 2903, 2859, 1472, 1429, 1176, 1113, 1049, 704.

LRMS (EI(+)) m/z 593 (M⁺ꢀt-Bu), 531, 277, 153, 73.

HRMS (EI(+)) calcd for C₂₉H₄₅O₇Si₂S ([Mꢀt-Bu]⁺)

593.2424, found 593.2424.

21

D

1

½aꢂ +7.0ꢁ (c 0.7, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.03 (6H, s), 0.87 (9H, s), 1.04 (9H, s), 1.14–1.20

(1H, m), 1.30–1.39 (2H, m), 1.42–1.62 (2H, m), 1.64–

1.80 (2H, m), 3.01 (1H, dd, J = 4.5, 9.6 Hz), 3.23 (1H,

dd, J = 6.5, 9.6 Hz), 3.35 (1H, dd, J = 2.7, 5.3 Hz),

3.37 (3H, s), 3.63 (2H, t, J = 6.3 Hz), 3.86–3.93 (1H,

m), 4.41 (1H, d, J = 2.7 Hz), 7.20–7.24 (3H, m), 7.26–

7.30 (6H, m), 7.33–7.39 (6H, m), 7.47–7.49 (6H, m),

7.64–7.67 (4H, m). ¹³C NMR (100 MHz, CDCl₃, ppm)

d ꢀ4.7, ꢀ4.5, 18.2, 19.3, 25.9, 26.9, 27.1, 30.6, 37.6,

54.9, 64.1, 65.4, 66.7, 72.1, 86.4, 103.2, 126.8, 127.5,

127.7, 128.7, 129.4, 134.0, 135.5, 135.5, 144.1. IR (neat,

cm^ꢀ1) 2928, 2896, 2859, 1491, 1462, 1448, 1427, 1111,

1046, 775, 706. LRMS (FAB(+), NBA) m/z 838

([M+Na]⁺). HRMS (FAB(+), NBA) calcd for

C₅₁H₆₆O₅Si₂Na ([M+Na]⁺) 837.4346, found 837.4357.

3.5.9. Methyl 6-Bromo-2-O-(tert-butyldimethylsilyl)-3-C-

{3-(tert-butyldiphenylsilyloxy)propyl}-3,4,6-trideoxy-a-^D-

altropyranoside (20). Under an Ar atmosphere, to a

solution of the mesylate prepared as above (75.5 mg,

0.12 mmol) in 2-butanone (1.2 mL) was added LiBr

(52 mg, 0.60 mmol) and stirred at reﬂux for 7 h. After

cooled to room temperature, water (3 mL) was added,

and the mixture was extracted with AcOEt (30 mL).

The organic layer was washed with brine (3 mL), dried

(MgSO₄), and concentrated. Puriﬁcation by silica gel

column chromatography (hexane/AcOEt (9:1)) gave

the bromide 20 (67.2 mg, 91%) as a colorless oil.

3.5.7. Methyl 2-O-(tert-Butyldimethylsilyl)-3-C-{3-(tert-

butyldiphenylsilyloxy)propyl}-3,4-dideoxy-a-^D-altro-pyrano-

side. Under an Ar atmosphere, to a cooled (ꢀ15 ꢁC)

solution of 19 (309 mg, 0.38 mmol) in CH₂Cl₂

(3.8 mL) was added Et₂AlCl (0.9 M in hexane, 989 lL,

0.92 mmol) and stirred at the same temperature for

5 min. The reaction was quenched by the addition of

saturated aqueous NaHCO₃solution (10 mL), and the

mixture was extracted with Et₂O (200 mL). The organic

layer was washed with brine (15 mL), dried (MgSO₄),

and concentrated. Puriﬁcation by silica gel column chro-

matography (hexane/AcOEt (5:1)) gave the product

(202 mg, 93%) as a colorless oil.

22

D

½aꢂ +19.4ꢁ (c 4.4, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.02 (3H, s), 0.04 (3H, s), 0.88 (9H, s), 1.05 (9H,

s), 1.35 (1H, dt, J = 3.8, 13.3 Hz), 1.41–1.61 (3H, m),

1.62–1.74 (2H, m), 1.81–1.88 (1H, m), 3.34 (1H, dd,

J = 4.6, 10.5 Hz), 3.37 (3H, s), 3.38–3.43 (2H, m), 3.66

(2H, t, J = 6.3 Hz), 3.91–3.98 (1H, m), 4.46 (1H, d,

J = 2.2 Hz), 7.36–7.44 (6H, m), 7.65–7.68 (4H, m). ¹³C

NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.6, 18.2,

19.3, 25.9, 25.9, 26.7, 26.7, 29.2, 30.7, 35.8, 38.3, 55.1,

63.9, 65.7, 70.9, 103.2, 127.5, 129.4, 133.9, 135.5,

135.5. IR (neat, cm^ꢀ1) 2953, 2955, 2934, 2892, 2855,

1684, 1651, 1458, 1115, 1035, 702. LRMS (EI(+)) m/z

603 ([MꢀOMe]⁺), 545 ([Mꢀt-BuꢀMeOH]⁺), 289, 197.

HRMS (EI(+)) calcd for C₃₁H₄₈O₃⁷⁹BrSi₂([MꢀOMe]⁺)

603.2325, found 603.2325.

22

D

½aꢂ +17.2ꢁ (c 1.1, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.03 (3H, s), 0.05 (3H, s), 0.88 (9H, s), 1.05 (9H,

s), 1.14 (1H, dt, J = 3.8, 13.2 Hz), 1.44–1.75 (5H, m),

1.82–1.88 (1H, m), 2.01 (1H, br s), 3.33 (3H, s), 3.43

(1H, dd, J = 2.1, 4.2 Hz), 3.57 (2H, br t, J = 4.5 Hz),

3.65 (2H, t, J = 6.3 Hz), 3.83–3.89 (1H, m), 4.45 (1H,

d, J = 2.1 Hz), 7.35–7.43 (6H, m), 7.65–7.67 (4H, m).

¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.6, 18.2,

19.3, 25.9, 26.2, 27.0, 30.8, 37.6, 54.9, 64.0, 65.7, 66.0,

71.2, 103.1, 127.5, 129.4, 134.0, 135.5, 135.5. IR (neat,

cm^ꢀ1) 3476, 2930, 2897, 2859, 1653, 1557, 1541, 1111,

1044, 702. LRMS (EI(+)) m/z 541 ([MꢀOCH₃]⁺), 397,

321, 295. HRMS calcd for C₃₁H₄₉O₄Si₂([MꢀOCH₃]⁺)

541.3169, found 541.3168.

3.5.10. (2S,3R)-2-{(tert-Butyldimethylsilyl)oxy}-3-(tert-

butyldiphenylsilyloxy)hex-5-en-1-ol (21). Under an Ar

atmosphere, to a solution of 20 (136 mg, 0.21 mmol) in

n-propanol (3 mL) was added water (500 lL) and

warmed to 110 ꢁC. Zn dust (activated by sequential

treatment with dil. HCl aq, water, EtOH, and Et₂O,

696 mg, 10.7 mmol) and NaBH₃CN (402 mg, 6.4 mmol)

were added and stirred at the same temperature for

20 min. Another Zn dust (696 mg, 10.7 mmol) and

NaBH₃CN (402 mg, 6.4 mmol) were added and stirred

at the same temperature for 20 min. The mixture was

cooled to room temperature, and insoluble materials

were ﬁltered oﬀ through Celite, and washed with AcOEt

and water. The organic layer of the ﬁltrate was washed

with brine (5 mL), dried (MgSO₄), and concentrated.

Puriﬁcation by silica gel column chromatography

3.5.8. Methyl 2-O-(tert-Butyldimethylsilyl)-3-C-{3-(tert-

butyldiphenylsilyloxy)propyl}-3,4-dideoxy-6-O-(methane-

sulfonyl)-a-^D-altropyranoside. Under an Ar atmosphere,

to a cold (0 ꢁC) solution of the alcohol prepared as

above (200 mg, 0.35 mmol) in CH₂Cl₂(3 mL) were

added Et₃N (397 lL, 1.05 mmol), and MsCl (81 lL,

1.05 mmol) and stirred at the same temperature for

5 min. The reaction was quenched by the addition of

water (10 mL), and the mixture was extracted with

AcOEt (200 mL). The organic layer was washed with

brine (10 mL), dried (MgSO₄), and concentrated. Puriﬁ-

cation by silica gel column chromatography (hexane/

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3017

(hexane/AcOEt (15:1)) gave the alcohol 21 (92 mg, 81%)

as a colorless oil.

4.6 Hz), 2.72–3.63 (2H, m), 3.63 (1H, dd, J = 2.8,

6.4 Hz), 3.67 (1H, dd, J = 2.8, 6.4 Hz), 5.02 (1H, br d,

J = 10.5 Hz), 5.06 (1H, br d, J = 17.8 Hz), 5.78 (1H,

ddt, J = 7.2, 10.4, 17.4 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d 29.1, 30.0, 36.2, 41.3, 46.6, 56.0, 63.2,

116.5, 135.9. IR (neat, cm^ꢀ1) 1601, 1584, 1453. LRMS

(EI(+)) m/z 156 (M⁺), 125 ([MꢀCH₂OH]⁺), 107. HRMS

(EI(+)) calcd for C₉H₁₆O₂(M⁺), 156.1150, found

156.1152.

21

D

1

½aꢂ ꢀ0.9ꢁ (c 0.2, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.07 (3H, s), 0.09 (3H, s), 0.90 (9H, s), 1.04 (9H,

s), 1.31–1.43 (2H, m), 1.53–1.62 (2H, m), 1.72 (1H, t,

J = 6.3 Hz), 1.90 (1H, dt, J = 7.4, 13.8 Hz), 2.31 (1H, dt,

J = 7.4, 13.8 Hz), 3.54 (2H, t, J = 5.6 Hz), 3.63 (2H, t,

J = 6.3 Hz), 3.74–3.77 (1H, m), 4.98 (1H, d,

J = 10.0 Hz), 5.00 (1H, d, J = 17.1 Hz), 5.73 (1H, ddt,

J = 7.1, 10.0, 17.1 Hz), 7.35–7.44 (6H, m), 7.65–7.67

(4H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.4,

ꢀ4.4, 18.2, 19.3, 25.8, 25.9, 26.9, 30.7, 36.2, 34.3, 41.6,

63.7, 64.1, 115.9, 127.5, 129.5, 133.9, 135.5, 137.6. IR

(neat, cm^ꢀ1) 3443, 3073, 2932, 2894, 2857, 1640, 1472,

1428, 1113, 1007, 704. LRMS (EI(+)) m/z 508

([MꢀH₂O]⁺), 495 ([MꢀOMe]⁺), 467, 199. HRMS

(EI(+)) calcd for C₃₁H₄₈O₂Si₂([MꢀH₂O]⁺) 508.3187,

found 508.3190.

3.5.13. (4R,5S)-4-{3-(tert-Butyldimethylsilyloxy)propyl}-

5,6-epoxyhex-1-ene (22). Under an Ar atmosphere, to a

solution of the epoxy alcohol prepared as above

(47.6 mg, 0.31 mmol) in CH₂Cl₂(3 mL) were added

Et₃N (86 mL, 0.62 mmol), TBSCl (93 mg, 0.62 mmol),

and DMAP (38 mg, 0.31 mmol), and stirred at room

temperature for 1 h. DMAP (38 mg, 0.31 mmol) was

added and stirred at room temperature for 1 h. The mix-

ture was diluted with AcOEt (50 mL), washed with

water (5 mL), brine (5 mL), dried (MgSO₄), and concen-

trated. Puriﬁcation by silica gel column chromatography

(hexane/AcOEt (15:1)) gave the product 22 (71.6 mg,

85%) as a colorless oil.

3.5.11. 4-{(1S)-1-(tert-Butyldimethylsilyloxy)-2-(p-tolu-

enesulfonyloxy)}ethyl-7-(tert-butyldiphenylsilyloxy) hept-

1-ene. Under an Ar atmosphere, to a solution of 21

(95 mg, 0.18 mmol) in CH₂Cl₂(2 mL) were added TsCl

(38 mg, 0.20 mmol), Et₃N (62 lL, 0.45 mmol), and

DMAP (44 mg, 0.36 mmol), and stirred at room temper-

ature for 4 h. The reaction mixture was diluted with

AcOEt (30 mL) and washed with water (3 mL) and

brine (3 mL), dried (MgSO₄), and concentrated. Puriﬁ-

cation by silica gel column chromatography (hexane/

AcOEt (15:1)) gave the tosylate (112 mg, 91%) as a col-

orless oil.

21

D

1

½aꢂ ꢀ0.6ꢁ (c 1.2, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (6H, s), 0.89 (9H, s), 1.20–1.25 (1H, m),

1.47–1.53 (2H, m), 1.58–1.67(2H, m), 2.10 (1H, dd,

J = 7.1, 14.0 Hz), 2.17 (1H, dd, J = 7.1, 14.0 Hz), 2.49

(1H, dd, J = 3.4, 4.4 Hz), 2.71–2.75 (2H, m), 3.61 (2H,

t, J = 6.3 Hz), 5.01 (1H, br d, J = 11.2 Hz), 5.05 (1H,

br d, J = 19.0 Hz), 5.78 (1H, ddt, J = 7.1, 10.3,

17.2 Hz). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ5.2,

0.1, 18.4, 26.0, 28.7, 32.1, 36.0, 46.5, 55.9, 63.2, 116.3,

136.1. IR (neat, cm^ꢀ1) 2953, 2930, 2901, 2859, 1640,

1255, 1101. LRMS (EI(+)) m/z 213 ([Mꢀt-Bu]⁺), 183,

101. HRMS (EI(+)) calcd for C₁₁H₂₁O₂Si ([Mꢀt-Bu]⁺)

213.1311, found 213.1287.

21

D

1

½aꢂ +7.6ꢁ (c 0.3, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.01 (6H, s), 0.84 (9H, s), 1.03 (9H, s), 1.22–1.54

(5H, m), 1.90 (1H, dt, J = 7.0, 14.1 Hz), 2.16 (1H, dt,

J = 7.0, 14.1 Hz), 2.42 (3H, s), 3.56 (1H, dd, J = 5.2,

10.0 Hz), 3.61 (1H, dd, J = 6.2, 10.0 Hz), 3.88 (2H, t,

J = 6.3 Hz), 3.93–3.96 (1H, m), 4.95–4.99 (2H, m),

5.61–5.71 (1H, m), 7.31 (2H, d, J = 8.2 Hz), 7.36–7.45

(6H, m), 7.64–7.66 (4H, m), 7.77 (2H, d, J = 8.2 Hz).

¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.2, 18.1,

19.2, 21.7, 25.2, 25.8, 26.9, 30.6, 34.3, 41.7, 63.9, 71.4,

71.7, 116.2, 127.5, 127.9, 129.5, 129.7, 133.9, 135.5,

137.1, 144.6. IR (neat, cm^ꢀ1): 2995, 2924, 2911, 2861,

1599, 1364, 1179, 1111, 704. LRMS (EI(+)) m/z 623

([Mꢀt-Bu]⁺), 451, 427, 229. HRMS (EI(+)) calcd for

C₃₄H₄₇O₅Si₂S ([Mꢀt-Bu]⁺) 623.2682, found 623.2687.

3.5.14. (4R,5R)-5-{3-(tert-Butyldimethylsilyloxy)propyl}-

1-(trimethylsilyl)oct-7-en-1-yn-4-ol. Under an Ar atmo-

sphere, to a cooled (ꢀ78 ꢁC) solution of TMS acetylene

(49 lL, 0.35 mmol) in THF (2 mL) was added n-BuLi

(1.5 M in hexane, 189 lL, 0.3 mmol) and stirred at the

same temperature for 10 min. To the resulting lithium

acetylide solution was added a solution of 22 (27.2 mg,

0.10 mmol) in THF (2 mL) via cannula, and then

BF₃ÆOEt₂(14 mL, 0.11 mmol) was added. The mixture

was stirred at the same temperature for 25 min. The reac-

tion was quenched by the addition of saturated aqueous

NaHCO₃solution (10 mL), and the mixture was ex-

tracted with AcOEt (100 mL). The organic layer was

washed with brine (10 mL), dried (MgSO₄), and concen-

trated. Puriﬁcation by silica gel column chromatography

(hexane/AcOEt (20:1)) gave enyne (26.3 mg, 71%) as a

colorless oil.

3.5.12. (4R)-4-[(S)-Oxiranyl]hept-6-en-1-ol. Under an Ar

atmosphere, to a solution of the tosylate prepared as

above (92 mg, 0.14 mmol) in THF (1.4 mL) was added

TBAF (1 M in THF, 1 mL, 1 mmol) and stirred at room

temperature for 1.5 h. The mixture was diluted with

AcOEt (20 mL) and washed with saturated aqueous

NH₄Cl solution (2 mL), brine (2 mL), dried (MgSO₄),

and concentrated. Puriﬁcation by silica gel column chro-

matography (hexane/AcOEt (5:1 to 1:1)) gave the epox-

ide (16 mg, 75%) as a colorless oil.

23

D

1

½aꢂ +0.9ꢁ (c 2.0, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.04 (6H, s), 0.15 (9H, s), 0.89 (9H, s), 1.31–1.40

(1H, m), 1.42–1.67 (4H, m), 2.04 (1H, dt, J = 7.1,

14.0 Hz), 2.22 (1H, dt, J = 7.1, 14.0 Hz), 2.40 (1H, dd,

J = 7.3, 16.8 Hz), 2.45 (1H, dd, J = 5.4, 16.8 Hz), 3.59

(2H, t, J = 6.4 Hz), 3.72–3.77 (1H, m), 5.02 (1H, br d,

J = 10.1 Hz), 5.06 (1H, br d, J = 17.4 Hz), 5.78 (1H,

21

D

1

½aꢂ +6.4ꢁ (c 1.2, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 1.21–1.30 (1H, m), 1.53–1.59 (1H, m), 1.65–1.74

(2H, m), 2.09–2.17 (2H, m), 2.49 (1H, dd, J = 3.2,

3018

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

ddt, J = 7.1, 10.1, 17.4 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ5.3, 0.0, 18.2, 24.5, 25.9, 26.0, 30.3,

34.5, 41.9, 63.2, 71.3, 87.3, 103.4, 116.2, 136.7. IR (neat,

cm^ꢀ1) 2957, 2932, 2903, 2859, 2176, 1252, 1009, 845.

LRMS (EI(+)) m/z 368 (M⁺), 311 ([Mꢀt-Bu]⁺), 293

([Mꢀt-BuꢀH₂O]⁺), 219. HRMS (EI(+)) calcd for

C₂₀H₄₀O₂Si₂(M⁺) 368.2567, found 368.2559.

LRMS (EI(+)) m/z 410 (M⁺), 353 ([Mꢀt-Bu]⁺), 221,

147. HRMS (EI(+)) calcd for C₂₃H₄₆O₂Si₂(M⁺)

410.3019, found 410.3028.

3.5.17. 2a-(3-Hydroxypropyl)-25-hydroxyvitamin D₃(3).

Under an Ar atmosphere, a mixture of A-ring enyne 23

(4.4 mg, 10.7 lmol), CD-ring bromooleﬁn 6¹²(20.0 mg,

56.0 lmol), Pd(PPh₃)₄(6.3 mg, 5.5 lmol), PhMe

(500 lL), and Et₃N (1.0 mL) was stirred at 110 ꢁC for

2 h. After cooled to room temperature, the mixture

was diluted with Et₂O and ﬁltered through Celite. The

ﬁltrate was diluted with AcOEt (20 mL), and washed

with water (2· 1 mL), brine (1 mL), dried (MgSO₄),

and concentrated. The residue was partially puriﬁed

through silica gel pad (eluent: hexane/AcOEt (20:1)) to

remove polar materials and dissolved in THF (50 lL).

The TBAF solution (1 M in THF, 110 lL, 0.11 mmol)

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

The mixture was partitioned between AcOEt (20 mL)

and water (1 mL), and the organic layer was washed

with water (1 mL) and brine (1 mL), dried (MgSO₄),

and concentrated. Puriﬁcation by preparative TLC

(AcOEt) gave the product (1.7 mg, 35% for 2 steps) as

a while amorphous.

3.5.15. (4R,5R)-5-{3-(tert-Butyldimethylsilyloxy)propyl}-

oct-7-en-1-yn-4-ol. The enyne alcohol prepared as above

(26.3 mg, 0.071 mmol) was dissolved in MeOH (500 mL)

and to the solution was added K₂CO₃(14.7 mg,

0.107 mmol). After stirred at room temperature for 3.5 h,

the reaction mixture was diluted with saturated aqueous

NH₄Cl solution (3 mL), and the mixture was extracted

with AcOEt (30 mL). The organic layer was washed with

brine (3 mL), dried (MgSO₄), and concentrated. Puriﬁca-

tion by silica gel column chromatography (PhMe/AcOEt

(15:1)) gave the product (17.5 mg, 83%) as a colorless

oil.

22

D

1

½aꢂ ꢀ5.0ꢁ (c 1.4, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (6H, s), 0.89 (9H, s), 1.36–1.42 (1H, m),

1.44–1.54 (2H, m), 1.59–1.68 (2H, m), 2.02–2.10 (3H,

m), 2.23 (1H, dt, J = 6.9, 14.0 Hz), 2.40 (1H, t,

J = 2.7 Hz), 2.41 (1H, dd, J = 1.1, 2.7 Hz), 3.60 (2H, t,

J = 6.3 Hz), 3.75–3.80 (1H, m), 5.04 (1H, br d,

J = 10.0 Hz), 5.07 (1H, br d, J = 17.1 Hz), 5.79 (1H,

ddt, J = 7.1, 10.0, 17.9 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ5.2, 18.4, 24.6, 24.7, 26.0, 26.0, 30.3, 34.7, 42.0,

63.3, 70.6, 71.6, 81.3, 116.3, 136.7. IR (neat, cm^ꢀ1) 3422,

3306, 2934, 2859, 2116, 1638, 1256, 1098, 837, 700. LRMS

(EI(+)) m/z 239 ([Mꢀt-Bu]⁺), 221([Mꢀt-BuꢀH₂O]⁺),

147, 105. HRMS (EI(+)) calcd for C₁₃H₂₃O₂Si ([Mꢀt-

Bu]⁺) 239.1467, found 239.1465.

18

D

½aꢂ +27.0ꢁ (c 0.04, CHCl₃). ¹H NMR (600 MHz,

CDCl₃, ppm) d 0.54 (3H, s), 0.93 (3H, d, J = 6.6 Hz),

1.03–1.08 (1H, m), 1.19–1.20 (1H, m), 1.21 (6H, s),

1.23–1.33 (5H, m), 1.36–1.49 (9H, m), 1.51–1.73 (8H,

m), 1.84–1.93 (2H, m), 1.96–2.02 (2H, m), 2.25 (1H,

dd, J = 8.8, 13.1 Hz), 2.47 (1H, dd, J = 4.5, 13.7 Hz),

2.61 (1H, dd, J = 4.0, 13.1 Hz), 2.82 (1H, dd, J = 3.5,

12.1 Hz), 3.55–3.59 (1H, m), 3.67 (2H, br s), 4.83 (1H,

s), 5.04 (1H, s), 6.02 (1H, d, J = 11.3 Hz), 6.22 (1H, d,

J = 11.3 Hz). ¹³C NMR (150 MHz, CDCl₃, ppm) d

12.0, 18.8, 20.8, 22.2, 23.5, 27.7, 27.8, 29.0, 29.2, 29.4,

29.8, 36.1, 36.4, 37.9, 40.5, 44.4, 44.4, 44.6, 45.9, 56.4,

56.3, 56.5, 63.1, 71.2, 73.5, 113.0, 117.4, 121.9, 135.2,

142.4, 144.1. IR (ﬁlm, cm^ꢀ1) 3374, 2951, 2928, 2897,

2851, 1674, 1615, 1555, 1458, 1053. LRMS (EI(+)) m/z

458 (M⁺), 440 ([MꢀH₂O]⁺), 341, 311. HRMS (EI(+))

calcd for C₃₀H₅₀O₃(M⁺) 458.3760, found 458.3758.

3.5.16. (4R,5R)-5-(tert-Butyldimethylsilyloxy)-4-{3-(tert-

butyldimethylsilyloxy)propyl}oct-1-en-7-yne (23). Under

an Ar atmosphere, to a cold (0 ꢁC) solution of the alco-

hol prepared as above (17.5 mg, 0.059 mmol) in CH₂Cl₂

(600 mL) were added 2,6-lutidine (20 lL, 0.177 mmol)

and TBSOTf (20 lL, 0.089 mmol), and stirred at the

same temperature for 1 h. The reaction was quenched

by the addition of saturated aqueous NaHCO₃solution

(3 mL), and the mixture was extracted with AcOEt

(30 mL). The organic layer was washed with brine

(3 mL), dried (MgSO₄) and concentrated. Puriﬁcation

by silica gel column chromatography (hexane/AcOEt

(100:1)) gave the product 23 (24 mg, quant.) as a color-

less oil.

3.6. Synthesis of 1a- and 1b-hydroxymethyl-2-unsubsti-

tuted analogues (4a, 4b)

3.6.1. (2R,3S,5S,6S)-2-Benzyloxymethyl-5-(tert-butyldi-

methylsilyloxy)-6-methoxytetrahydropyran-3-ol

(25).

Under an Ar atmosphere, to a suspension of 24¹⁷

(93.1 mg, 0.245 mmol), MS3A (241.1 mg), and Et₃SiH

(195 lL, 1.22 mmol) in CH₂Cl₂(2.5 mL) was added

TFA (95 lL, 1.23 mmol) and stirred at 0 ꢁC, and grad-

ually raised up to room temperature for 6 h. The reac-

tion was quenched by the addition of saturated

aqueous Na₂CO₃solution (5 mL), and the mixture

was ﬁltered through Celite pad and the solid was

washed with CH₂Cl₂and water. Layers were separated,

and the aqueous layer was extracted with CH₂Cl₂

(5 mL). The combined organic layers were washed with

brine (5 mL), dried (Na₂SO₄), and concentrated. Puriﬁ-

cation by silica gel column chromatography (hexane/

AcOEt (5:1)) gave the products 25 (69.6 mg, 76%,) as

a colorless oil.

21

D

1

½aꢂ ꢀ6.5ꢁ (c 1.9, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (6H, s), 0.06 (3H, s), 0.08 (3H, s), 0.89 (9H,

s), 0.89 (9H, s), 1.24–1.73 (6H, m), 1.99 (1H, dt, J = 7.0,

14.0 Hz), 2.21 (1H, dt, J = 7.0, 14.0 Hz), 2.29 (1H, ddd,

J = 2.7, 6.4, 16.8 Hz), 2.36 (1H, ddd, J = 2.7, 6.4,

16.8 Hz), 3.59 (2H, t, J = 6.3 Hz), 3.87 (1H, ddd,

J = 3.2, 6.4, 6.4 Hz), 5.03 (2H, dd, J = 10.1, 17.1 Hz),

5.77 (1H, ddt, J = 7.0, 10.1, 17.1 Hz). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ5.2, ꢀ4.6, ꢀ4.1, 18.1,

18.4, 24.4, 24.9, 25.9, 26.0, 31.0, 34.7, 42.5, 63.5, 69.8,

72.3, 82.1, 115.7, 137.7. IR (neat, cm^ꢀ1) 2957, 2930,

2890, 2857, 2161, 1507, 1254, 1099, 837, 708, 671.

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3019

18

D

½aꢂ +35.6ꢁ (c 0.5, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

trated. Puriﬁcation by silica gel column chromatography

(hexane/AcOEt (15:1)) gave the exo-methylene com-

pound 26 (2.16 g, 82%) as a colorless oil.

ppm) d 0.05 (3H, s), 0.07 (3H, s), 0.89 (9H, s), 1.78 (1H,

ddd, J = 2.5, 11.2, 12.8 Hz), 1.95 (1H, ddd, J = 3.4, 4.6,

12.8 Hz), 2.63 (1H, br s), 3.37 (3H, s), 3.62–3.74 (2H, m),

3.78 (1H, dd, J = 4.8, 9.2 Hz), 3.83 (1H, m), 3.97 (1H,

ddd, J = 4.6, 9.0, 11.2 Hz), 4.39 (1H, s), 4.57 (1H, d,

J = 11.8 Hz), 4.64 (1H, d, J = 11.8 Hz), 7.26–7.38 (5H,

m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.8,

18.1, 25.8, 35.0, 54.7, 65.5, 68.4, 70.8, 72.2, 73.7, 100.3,

127.6, 127.7, 128.4, 137.7. IR (neat, cm^ꢀ1) 3445, 2930,

1464, 1256, 1132, 837, 735. LRMS (EI(+)) m/z 382

(M⁺), 363 ([MꢀH₂OꢀH]⁺), 351 ([MꢀOMe]⁺), 333

16

D

½aꢂ +73.1ꢁ (c 1.2, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (3H, s), 0.06 (3H, s), 0.88 (9H, s), 2.25 (1H,

dd, J = 6.2, 13.5 Hz), 2.54 (1H, dd, J = 4.4, 13.5 Hz),

3.43 (3H, s), 3.70 (1H, dd, J = 6.6, 14.2 Hz), 3.70–3.74

(1H, m), 3.75 (1H, dd, J = 4.6, 14.2 Hz), 4.37 (1H,

apparent t, J = 5.4 Hz), 4.53 (1H, d, J = 2.4 Hz), 4.58

(1H, d, J = 12.2 Hz), 4.64 (1H, d, J = 12.2 Hz), 4.83

(1H, s), 4.86 (1H, t, J = 2.0 Hz), 7.24–7.38 (5H, m).

¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.7, 18.2, 25.8,

37.5, 55.2, 70.0, 70.7, 71.1, 73.3, 102.6, 109.9, 127.4,

127.5, 128.2, 138.2, 141.3. IR (neat, cm^ꢀ1) 2930, 1655,

1472, 1256, 1183, 1100, 837. LRMS (EI(+)) m/z 378

(M⁺), 347 ([MꢀOMe]⁺), 321 ([Mꢀt-Bu]⁺), 289 ([Mꢀt-

BuꢀMeOH]⁺), 257 ([MꢀBnOCH₂]⁺), 210, 199, 153, 91

(C₇H₇, bp). HRMS (EI(+)) calcd for C₂₁H₃₄O₄Si (M⁺)

378.2226, found 378.2221.

([MꢀH₂OꢀOMe]⁺),

325

([Mꢀt-Bu]⁺),

307

([MꢀH₂Oꢀt-Bu]⁺), 293 ([Mꢀt-BuꢀMeOH]⁺), 275,

257, 225, 203, 185, 159, 101, 91 (C₇H₇, bp). HRMS

(EI(+)) calcd for C₂₀H₃₄O₅Si (M⁺) 382.2176, found

382.2175.

3.6.2. (2R,5S,6S)-2-Benzyloxymethyl-5-(tert-butyldimeth-

ylsilyloxy)-6-methoxytetrahydropyran-3-one. A mixture

of alcohol 25 (3.02 g, 7.89 mmol), MS4A (6.49 g),

NMO

(1.36 g,

11.6 mmol),

TPAP

(136.4 mg,

3.6.4. Hydroboration of the exo-methylene compound

(26). Under an Ar atmosphere, to a cold (0 ꢁC) solution

of exo-methylene compound 26 (2.16 g, 5.71 mmol) in

THF (20 mL) was added BH₃ÆTHF (1 M in THF,

11 mL, 11 mmol), and the mixture was stirred at the

same temperature for 1.5 h. 1 N NaOH solution

(10 mL) and 30% H₂O₂solution (10 mL) were added,

and the solution was stirred the same temperature for

1.5 h. The reaction was quenched by the addition of

10% aqueous Na₂S₂O₃solution (50 mL), and the mix-

ture was extracted with AcOEt (3· 250 mL). The com-

bined organic layers were washed with 10% aqueous

Na₂S₂O₃solution (50 mL), brine (50 mL), dried

(Na₂SO₄), and concentrated. Puriﬁcation by silica gel

column chromatography (hexane/AcOEt (8:1)) gave

27a (less polar isomer, 1.64 g, 72%) and 27b (more polar

isomer, 185.7 mg, 8%) as colorless oils, respectively.

0.388 mmol) in CH₂Cl₂(75 mL) was stirred at room

temperature for 0.5 h. The mixture was ﬁltered through

Celite, washed with CH₂Cl₂, and the solvent was re-

moved under reduced pressure. Puriﬁcation by silica

gel column chromatography (hexane/AcOEt (15:1))

gave the ketone (2.64 g, 88%) as a colorless oil.

19

D

½aꢂ +98.3ꢁ (c 1.1, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.05 (3H, s), 0.07 (3H, s), 0.87 (9H, s), 2.56 (1H,

dd, J = 6.1, 15.1 Hz), 2.74 (1H, dd, J = 4.4, 15.1 Hz),

3.49 (3H, s), 3.77 (1H, dd, J = 5.9, 10.8 Hz), 3.99 (1H,

dd, J = 2.9, 10.8 Hz), 4.06 (1H, ddd, J = 3.0, 4.4,

6.1 Hz), 4.18 (1H, dd, J = 2.9, 5.9 Hz), 4.57 (1H, d,

J = 12.2 Hz), 4.62 (1H, d, J = 12.2 Hz), 4.72 (1H, d,

J = 3.0 Hz), 7.24–7.36 (5H, m). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ4.8, ꢀ4.8, 18.0, 25.7, 44.4, 55.6,

68.8, 70.5, 73.5, 75.0, 101.9, 127.5, 127.5, 128.2,

138.0, 206.5. IR (neat, cm^ꢀ1) 2930, 1732, 1254, 1109,

837. LRMS (EI(+)) m/z 380 (M⁺), 349 ([MꢀOMe]⁺),

323 ([Mꢀt-Bu]⁺), 291 ([Mꢀt-BuꢀMeOH]⁺), 215, 201,

159, 145, 115, 101, 91 (C₇H₇), 89 (bp). HRMS

(EI(+)) calcd for C₂₀H₃₂O₅Si (M⁺) 380.2019, found

380.2008.

3.6.5. (2S,3S,5S,6S)-[2-Benzyloxymethyl-5-(tert-butyldi-

methylsilyloxy)-6-methoxytetrahydropyran-3-yl]methanol

20

D

1

(27a). ½aꢂ +24.4ꢁ (c 1.3, CHCl₃). H NMR (400 MHz,

CDCl₃, ppm) d 0.10 (6H, s), 0.91 (9H, s), 1.70 (1H,

m), 1.83 (1H, m), 2.14 (1H, ddd, J = 3.3, 5.9, 14.5 Hz),

3.38 (3H, s), 3.66 (1H, dt, J = 1.3, 3.3 Hz), 3.75 (1H,

dd, J = 6.1, 10.1 Hz), 3.74–3.83 (2H, m), 4.15 (1H, dt,

J = 3.2, 6.1 Hz), 4.48 (1H, s), 4.56 (1H, d,

J = 11.8 Hz), 4.63 (1H, d, J = 11.8 Hz), 7.25–7.38 (5H,

m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ5.0, ꢀ4.9,

18.1, 25.8, 30.9, 35.2, 54.6, 62.9, 66.5, 68.3, 71.0, 73.5,

101.2, 127.6, 128.3, 138.0. IR (KBr, cm^ꢀ1) 3472, 2928,

1468, 1258, 1123, 1030, 862, 700. LRMS (EI(+)) m/z

396 (M⁺), 379 ([MꢀOH]⁺), 365 ([MꢀMeO]⁺), 321

([Mꢀt-BuꢀH₂O]⁺), 307 ([Mꢀt-BuꢀMeOH]⁺), 289

([MꢀBnO]⁺), 231, 101, 91 (C₇H₇, bp). HRMS

(EI(+)) calcd for C₂₁H₃₆O₅Si (M⁺) 396.2332, found

396.2347.

3.6.3. (2S,3S,6S)-6-Benzyloxymethyl-3-(tert-butyldimeth-

ylsilyloxy)-2-methoxy-5-methylenetetrahydropyran (26).

Under an Ar atmosphere, to a cold (ꢀ40 ꢁC) mixture

of activated Zn dust (3.75 g, 57.4 mmol), CH₂Br₂

(1.2 mL, 17.1 mmol) in THF (40 mL) was added TiCl₄

(1.3 mL, 11.9 mmol), and the mixture was stirred at

5 ꢁC (cold room) for 4 d. The mixture was diluted with

CH₂Cl₂(20 mL), and a solution of ketone prepared as

above (2.64 g, 6.94 mmol) in CH₂Cl₂(25 mL) was

added. The mixture was stirred at room temperature

for 1 h. The reaction mixture was poured into a mixture

of Et₂O (100 mL)–saturated aqueous NaHCO₃solution

(100 mL) and stirred vigorously for several minutes.

Resulting mixture was ﬁltered through Celite, washed

with Et₂O and water, and the layers of the ﬁltrate were

separated. The organic layer was washed with water

(50 mL), brine (50 mL), dried (Na₂SO₄), and concen-

3.6.6. (2S,3R,5S,6S)-[2-Benzyloxymethyl-5-(tert-butyldi-

methylsilyloxy)-6-methoxytetrahydropyran-3-yl]methanol

21

D

1

(27b). ½aꢂ +34.3ꢁ (c 0.7, CHCl₃). H NMR (400 MHz,

CDCl₃, ppm) d 0.05 (6H, s), 0.89 (9H, s), 1.52 (1H,

m), 1.68 (1H, ddd, J = 2.7, 13.1, 13.1 Hz), 2.16 (1H,

3020

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

m), 2.75 (1H, br s), 3.36 (3H, s), 3.46 (1H, dd, J = 6.6,

11.7 Hz), 3.49 (1H, dd, J = 4.0, 11.7 Hz), 3.62–3.80

(4H, m), 4.43 (1H, s), 4.57 (1H, d, J = 11.6 Hz), 4.65

(1H, d, J = 11.8 Hz), 7.26–7.38 (5H, m). ¹³C NMR

(100 MHz, CDCl₃, ppm) d ꢀ4.8, ꢀ4.7, 18.1, 25.9, 30.1,

35.9, 54.6, 65.1, 66.8, 71.1, 72.8, 73.6, 100.8, 127.7,

127.8, 128.4, 137.5. IR (neat, cm^ꢀ1) 3476, 2930, 1464,

1256, 1190, 1129, 1055, 1019, 835. LRMS (EI(+)) m/z

396 (M⁺), 365 ([MꢀMeO]⁺), 347 ([MꢀOHꢀMeOH]⁺),

339 ([Mꢀt-Bu]⁺), 321 ([Mꢀt-BuꢀH₂O]⁺), 307 ([Mꢀt-

BuꢀMeOH]⁺), 289 ([MꢀBnO]⁺), 243, 101, 91 (C₇H₇,

bp). HRMS (EI(+)) calcd for C₂₁H₃₆O₅Si (M⁺)

396.2332, found 396.2349.

(20% dry basis, 40.5 mg) under H₂atmosphere for

3.5 h. Insoluble material was ﬁltered oﬀ, and the residue

in EtOH (5 mL) was further treated with Pd(OH)₂/C

(20% dry basis, 128.3 mg) under H₂atmosphere for

3.5 h. Insoluble material was ﬁltered oﬀ, concentrated,

and the crude alcohol was dissolved in CH₂Cl₂

(10 mL). Under an Ar atmosphere, the solution was

cooled to 0 ꢁC, and Et₃N (750 lL, 5.38 mmol) and MsCl

(210 lL, 2.71 mmol) were added. The mixture was stir-

red at the same temperature for 1 h, and the reaction

was quenched by the addition of water (10 mL). Result-

ing mixture was extracted with AcOEt (2· 30 mL), and

the organic layers were combined, washed with brine

(20 mL), dried (Na₂SO₄), and concentrated to give crude

mesylate. The crude mesylate was dissolved in TMU

(10 mL), and LiBr (489.9 mg, 5.64 mmol) was added.

The mixture was stirred under an Ar atmosphere at

80 ꢁC for 7 h. After cooled to room temperature, the

mixture was diluted with water (10 mL) and extracted

with Et₂O (2· 20 mL). The combined organic layers

were washed with water (10 mL), brine (10 mL), dried

(Na₂SO₄), and concentrated. Puriﬁcation by silica gel

column chromatography (hexane/AcOEt (25:1 to 4:1

to 2:1)) gave the bromide 28a (476.4 mg, 59% for four

steps) as a colorless oil.

3.6.7. Epimerization of 27a to 27b. A solution of 27a

(1.11 g, 2.80 mmol), NMO (485.2 mg, 4.14 mmol), and

TPAP (57.8 mg, 0.164 mmol) in CH₂Cl₂(15 mL) was

stirred at room temperature for 6 h. NMO (297.2 mg,

2.54 mmol) and TPAP (19.2 mg, 54.6 lmol) were

added, and the mixture was stirred at room tempera-

ture for another 4 h. TPAP (41.4 mg, 0.118 mmol)

was added, and the mixture was further stirred at the

same temperature for 12 h. NMO (241.3 mg,

2.06 mmol) was added, and the mixture was further

stirred at the same temperature for 6 h. The mixture

was washed with 10% aqueous Na₂S₂O₃solution

(50 mL), and aqueous layer was extracted with CH₂Cl₂

(50 mL). The combined organic layers were washed

with 0.1 N HCl solution (50 mL), water (50 mL), brine

(50 mL), dried (Na₂SO₄) and concentrated. The residue

was dissolved in MeOH (20 mL), and K₂CO₃(408 mg,

2.95 mmol) was added. The mixture was stirred at

room temperature for 20 min, and NaBH₄(175.0 mg,

4.62 mmol) was added. The mixture was further stirred

at the same temperature for 10 min. The reaction was

quenched by the addition of saturated aqueous NH₄Cl

solution (50 mL), and the mixture was extracted with

AcOEt (2· 50 mL). The combined organic layers were

washed with brine (50 mL), dried (Na₂SO₄), and con-

centrated. Puriﬁcation by silica gel column chromatog-

raphy (hexane/AcOEt (8:1)) gave the epimerized 27b

(650.2 mg, 59%), accompanied by the starting material

27a (15%).

22

D

½aꢂ +58.6ꢁ (c 0.4, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.06 (3H, s), 0.07 (3H, s), 0.91 (9H, s), 1.19 (9H,

s), 1.72 (1H, m), 2.00–2.10 (2H, m), 3.46 (3H, s), 3.40–

3.55 (2H, m), 3.61 (1H, m), 4.15 (1H, ddd, J = 1.8, 4.0,

9.0 Hz), 4.23 (1H, dd, J = 3.2, 11.9 Hz), 4.46 (1H, dd,

J = 8.6, 11.9 Hz), 4.49 (1H, s). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ5.0, ꢀ4.8, 18.0, 25.8, 27.3, 30.7, 34.1,

35.4, 38.6, 55.0, 64.7, 66.1, 70.3, 102.0, 178.0. IR (neat,

cm^ꢀ1) 2932, 1730, 1466, 1283, 1152, 1129, 1061, 1029,

837, 810, 777. LRMS (EI(+)) m/z 421 ([M(⁷⁹Br)ꢀ

MeO]⁺), 395 ([M(⁷⁹Br)ꢀt-Bu]⁺), 363 ([M(⁷⁹Br)ꢀt-

BuꢀMeOH]⁺), 293, 261, 211 (bp), 159. HRMS (EI(+))

calcd for C₁₈H₃₄⁷⁹BrO₄Si ([MꢀMeO]⁺) 421.1410, found

421.1418.

Compound 28b could be prepared according to essen-

tially the same manner (77% for four steps) as a colorless

oil.

3.6.8. (2S,3S,5S,6S)-2-Bromomethyl-5-(tert-butyldimeth-

ylsilyloxy)-6-methoxytetrahydropyran-3-ylmethyl piva-

late (28a). A solution of alcohol 27a (709.3 mg,

1.79 mmol), PivCl (330 lL, 2.68 mmol) in pyridine

(9 mL) was added at room temperature for 2.5 h. The

solvent was removed under reduced pressure, and the

residue was partitioned between AcOEt (30 mL) and

water (30 mL). The organic layer was washed with 1 N

HCl solution (20 mL) and water (20 mL), and the aque-

ous layers were combined and extracted with AcOEt

(20 mL). The combined organic layers were washed with

saturated aqueous Na₂CO₃solution (30 mL), brine

(30 mL), dried (Na₂SO₄), and concentrated to give crude

pivalate. The residue was dissolved in EtOH (5 mL), and

Pd(OH)₂/C (20% dry basis, 27.0 mg) was added. The

mixture was stirred under H₂atmosphere at room tem-

perature for 1 h. Insoluble materials were ﬁltered oﬀ and

the ﬁltrate was concentrated. The residue was re-dis-

solved in EtOH (5 mL) and treated with Pd(OH)₂/C

3.6.9. (2S,3R,5S,6S)-2-Bromomethyl-5-(tert-butyldimeth-

ylsilyloxy)-6-methoxytetrahydropyran-3-ylmethyl piva-

22

D

late (28b). ½aꢂ +51.8ꢁ (c 1.3, CHCl₃). ¹H NMR

(400 MHz, CDCl₃, ppm) d 0.06 (3H, s), 0.06 (3H, s),

0.90 (9H, s), 1.21 (9H, s), 1.63 (1H, ddd, J = 3.2, 3.2,

13.2 Hz), 1.80 (1H, ddd, J = 2.7, 13.2, 13.2 Hz), 2.37

(1H, m), 3.41 (3H, s), 3.50 (1H, dd, J = 7.0, 11.0 Hz),

3.67 (1H, dd, J = 2.1, 11.0 Hz), 3.70–3.78 (2H, m),

3.89 (1H, dd, J = 5.2, 11.7 Hz), 4.03 (1H, dd, J = 4.6,

11.7 Hz), 4.49 (1H, s). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ4.8, ꢀ4.7, 18.1, 25.8, 27.2, 30.1, 32.9, 34.9,

38.9, 54.8, 65.1, 66.4, 70.3, 100.7, 178.1. IR (neat,

cm^ꢀ1) 2932, 1732, 1474, 1285, 1256, 1144, 1113, 1032,

837, 776. LRMS (EI(+)) m/z 421 ([M(⁷⁹Br)ꢀMeO]⁺),

395 ([M(⁷⁹Br)ꢀt-Bu]⁺), 363 ([M(⁷⁹Br)ꢀt-BuꢀMeOH]⁺),

319, 293 (bp), 211, 159. HRMS (EI(+)) calcd for

C₁₈H₃₄⁷⁹BrO₄Si

421.1412.

([MꢀMeO]⁺)

421.1410,

found

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3021

21

D

3.6.10. (R)-2-[(S)-2-(tert-Butyldimethylsilyloxy)-3-hydroxy-

propyl]but-3-enyl pivalate (29a). A mixture of the bromide

28a (595.3 mg, 1.31 mmol), activated Zn dust (2.18 g,

33.3 mmol), and NaBH₃CN (615.5 mg, 9.79 mmol) in n-

PrOH (5 mL)–H₂O (0.5 mL) was stirred at 80 ꢁC for 6 h

and then 100 ꢁC for 6 h. After cooled to room temperature,

the mixture was diluted with saturated aqueous NH₄Cl solu-

tion (20 mL), ﬁltered through Celite, and washed with

AcOEt and water. After layers were separated, the aqueous

layer was extracted with AcOEt (20 mL), and organic layers

werecombined, washed withbrine(20 mL), dried (Na₂SO₄),

and concentrated. Puriﬁcation by silica gel column chroma-

tography (hexane/AcOEt (50:1 to 8:1 to 4:1)) gave ring

opened product 29a (337.0 mg, 75%) as a colorless oil.

½aꢂ ꢀ13.6ꢁ (c 0.3, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.00 (3H, s), 0.02 (3H, s), 0.84 (9H, s), 1.17 (9H,

s), 1.38–1.47 (1H, m), 1.52 (1H, ddd, J = 3.6, 8.0,

13.6 Hz), 2.45 (3H, s), 2.48–2.59 (1H, m), 3.80–3.91

(3H, m), 3.87 (1H, dd, J = 6.4, 10.7 Hz), 3.97 (1H, dd,

J = 6.2, 10.7 Hz), 5.03–5.14 (2H, m), 5.53 (1H, ddd,

J = 8.4, 10.4, 17.2 Hz), 7.32–7.38 (2H, m), 7.78–7.81

(2H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.6,

ꢀ4.1, 18.0, 21.7, 25.8, 27.2, 35.7, 38.8, 39.3, 67.1, 67.9,

73.2, 117.5, 127.9, 129.8, 132.8, 137.9, 144.8, 178.1. IR

(neat, cm^ꢀ1) 2930, 1727, 1480, 1352, 1285, 1175, 1130,

924, 835, 814, 777. LRMS (EI(+)) m/z 483 ([MꢀCH₃]⁺),

441 ([Mꢀt-Bu]⁺), 329, 313 ([MꢀCH₂OTs]⁺), 230 (bp),

211, 159. HRMS (EI(+)) calcd for C₂₄H₃₉O₆SSi

([MꢀCH₃]⁺) 483.2237, found 483.2238.

19

D

½aꢂ ꢀ14.5ꢁ (c 1.4, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.09 (6H, s), 0.90 (9H, s), 1.19 (9H, s), 1.49 (1H,

ddd, J = 4.4, 9.6, 14.0 Hz), 1.69 (1H, ddd, J = 4.2, 8.2,

14.0 Hz), 1.88 (1H, br s), 2.54 (1H, m), 3.47 (1H, dd,

J = 4.4, 11.1 Hz), 3.59 (1H, dd, J = 4.2, 11.1 Hz), 3.79

(1H, apparent dq, J = 8.2, 4.3 Hz), 3.94 (1H, dd,

J = 6.4, 10.8 Hz), 4.01 (1H, dd, J = 6.8, 10.8 Hz), 5.08–

5.16 (2H, m), 5.62 (1H, ddd, J = 8.5, 11.1, 16.3 Hz).

¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.4, ꢀ4.2, 18.1,

25.9, 27.2, 35.7, 38.8, 39.6, 66.9, 67.2, 70.7, 116.9,

138.5, 178.2. IR (neat, cm^ꢀ1) 3476, 2932, 1732, 1474,

1287, 1254, 1163, 837, 776. LRMS (EI(+)) m/z 313

([MꢀCH₂OH]⁺), 287 ([Mꢀt-Bu]⁺), 211, 185, 159, 117

(bp). HRMS (EI(+)) calcd for C₁₇H₃₃O₃Si

([MꢀCH₂OH]⁺) 313.2199, found 313.2193.

Tosylate from 29b could be prepared as essentially the

same manner (93%) as a colorless oil.

3.6.13. (S)-2-[(S)-2-(tert-Butyldimethylsilyloxy)-3-(4-tol-

uenesulfonyloxy)propyl]but-3-enyl pivalate. ½aꢂ +14.4ꢁ

20

D

1

(c 0.2, CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d

0.00 (3H, s), 0.02 (3H, s), 0.83 (9H, s), 1.17 (9H, s), 1.46

(1H, ddd, J = 5.2, 8.8, 13.9 Hz), 1.62 (1H, ddd, J = 6.3,

6.3, 13.9 Hz), 2.34–2.50 (1H, m), 2.45 (3H, s), 3.82–3.96

(3H, m), 3.90 (1H, dd, J = 5.4, 10.7 Hz), 3.95 (1H, dd,

J = 6.8, 10.7 Hz), 4.98–5.08 (2H, m), 5.58 (1H, ddd,

J = 8.6, 10.2, 17.0 Hz), 7.31–7.38 (2H, m), 7.76–7.82

(2H, m). ¹³C NMR (100 MHz, CDCl₃, ppm) d ꢀ4.8,

ꢀ4.5, 18.0, 21.7, 25.7, 27.2, 35.4, 38.8, 39.4, 66.3, 68.0,

72.7, 117.0, 127.9, 129.7, 132.8, 138.2, 144.7, 178.1. IR

(neat, cm^ꢀ1) 2934, 1730, 1460, 1366, 1285, 1179, 988,

839, 810, 781. LRMS (EI(+)) m/z 483 ([MꢀCH₃]⁺), 441

([Mꢀt-Bu]⁺), 339, 329, 313 ([MꢀCH₂OTs]⁺), 229 (bp),

211, 159. HRMS (EI(+)) calcd for C₂₄H₃₉O₆SSi

([MꢀCH₃]⁺) 483.2237, found 483.2250.

Compound 29b could also be prepared according to

essentially the same manner (61%) as a colorless oil.

3.6.11. (S)-2-[(S)-2-(tert-Butyldimethylsilyloxy)-3-hydroxy-

19

D

propyl]but-3-enyl pivalate (29b). ½aꢂ

+26.0ꢁ (c 0.2,

CHCl₃). ¹H NMR (400 MHz, CDCl₃, ppm) d 0.08 (6H, s),

0.90 (9H, s), 1.19 (9H, s), 1.49 (1H, ddd, J = 5.0, 9.3,

13.9 Hz), 1.69 (1H, ddd, J = 5.1, 8.5, 13.9 Hz), 1.90 (1H,

br s), 2.41 (1H, m), 3.45 (1H, dd, J = 5.0, 11.3 Hz), 3.60

(1H, dd, J = 3.5, 11.3 Hz), 3.80 (1H, dddd, J = 3.5, 5.0,

5.0, 8.5 Hz), 3.94 (1H, dd, J = 5.6, 10.8 Hz), 4.01 (1H, dd,

J = 7.2, 10.8 Hz), 5.05–5.14 (2H, m), 5.63 (1H, ddd,

J = 8.8, 10.4, 16.8 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ4.5, ꢀ4.4, 18.1, 25.9, 27.2, 34.9, 38.8, 40.0, 65.5,

66.7, 70.5, 116.9, 138.4, 178.2. IR (neat, cm^ꢀ1) 3484, 2932,

1732, 1480, 1287, 1256, 1159, 837, 756. LRMS (EI(+)) m/z

313 ([MꢀCH₂OH]⁺), 287 ([Mꢀt-Bu]⁺), 211, 185, 159, 117

(bp). HRMS (EI(+)) calcd for C₁₇H₃₃O₃Si ([MꢀCH₂OH]⁺)

313.2199, found 313.2200.

3.6.14. (R)-2-[(S)-2-Oxiranylmethyl]but-3-enyl pivalate

(30a). To a solution of tosylate (88.9 mg, 0.178 mmol) in

THF (0.75 mL) was added TBAF (1 M in THF, 445 lL,

445 lmol), and the solution was stirred at room temperature

for 3 h. The reaction was quenched by the addition of satu-

rated aqueous NH₄Cl solution (2 mL) and the mixture was

extracted with AcOEt (2·2 mL). The combined organic lay-

ers were washed with brine (2 mL), dried (Na₂SO₄), and

concentrated. Puriﬁcation by silica gel column chromatog-

raphy (hexane/AcOEt (15:1 to 4:1)) gave epoxide 30a

(30.1 mg, 80%) as a colorless oil.

21

D

1

½aꢂ ꢀ22.9ꢁ (c 0.2, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 1.19 (9H, s), 1.55–1.68 (2H, m), 2.48 (1H, dd,

J = 2.8, 5.0 Hz), 2.68 (1H, m), 2.78 (1H, dd, J = 4.4,

5.0 Hz), 2.96 (1H, m), 4.03 (1H, dd, J = 6.6, 10.7 Hz), 4.07

(1H, dd, J = 6.4, 10.7 Hz), 5.11–5.21 (2H, m), 5.69 (1H,

ddd, J = 8.6, 10.2, 17.4 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d 27.2, 34.5, 38.8, 41.2, 47.6, 50.4, 66.6, 117.1, 137.7,

178.2. IR (neat, cm^ꢀ1) 2975, 1730, 1482, 1285, 1157, 1038,

994, 926. LRMS (EI(+)) m/z 212 (M⁺), 182 ([MꢀCH₂O]⁺),

57 (t-Bu, bp). HRMS (EI(+)) calcd for C₁₂H₂₀O₃(M⁺)

212.1412, found 212.1412.

3.6.12. (R)-2-[(S)-2-(tert-Butyldimethylsilyloxy)-3-(4-tolu-

enesulfonyloxy)propyl]but-3-enyl pivalate. Under an Ar

atmosphere,

a solution of alcohol 29a (70.2 mg,

0.203 mmol), Et₃N (85 lL, 0.610 mmol), DMAP

(24.7 mg, 0.202 mmol), TsCl (56.9 mg, 0.298 mmol) in

CH₂Cl₂(1 mL) was stirred at room temperature for 13 h.

The reaction was quenched by the addition of water

(5 mL), and the mixture was extracted with AcOEt

(5 mL). The organic layer was washed with brine (5 mL),

dried (Na₂SO₄), and concentrated. Puriﬁcation by silica

gel column chromatography (hexane/AcOEt (15:1)) gave

tosylate (88.9 mg, 88%) as a colorless oil.

Compound 30b could also be prepared essentially in the

same manner (81%).

3022

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3.6.15. (S)-2-[(S)-2-Oxiranylmethyl]but-3-enyl pivalate

(30b). ½aꢂ +5.6ꢁ (c 0.1, CHCl₃). H NMR (400 MHz,

17.9 Hz). ¹³C NMR (100 MHz, CDCl₃, ppm) d 27.3,

37.5, 43.3, 65.3, 67.9, 71.0, 80.6, 117.1, 139.2. IR (neat,

cm^ꢀ1) 3357, 3299, 3081, 2934, 2120, 1642, 1422, 1038,

918. LRMS (EI(+)) m/z 154 (M⁺), 135 ([MꢀH₂OꢀH]⁺),

115 ([MꢀC₃H₃]⁺), 97 (bp). HRMS (EI(+)) calcd for

C₉H₁₄O₂(M⁺) 154.0994, found 154.0998.

22

D

1

CDCl₃, ppm) d 1.19 (9H, s), 1.63 (1H, ddd, J = 6.0,

6.0, 14.1 Hz), 1.69 (1H, ddd, J = 6.0, 7.8, 14.1 Hz),

2.47 (1H, dd, J = 2.7, 5.0 Hz), 2.63 (1H, m), 2.77 (1H,

m), 2.97 (1H, ddt, J = 2.7, 3.9, 6.0 Hz), 4.03 (1H, dd,

J = 5.8, 11.0 Hz), 4.09 (1H, dd, J = 6.6, 11.0 Hz), 5.10–

5.19 (2H, m), 5.75 (1H, ddd, J = 8.0, 10.4, 17.2 Hz).

¹³C NMR (100 MHz, CDCl₃, ppm) d 27.2, 34.3, 38.8,

41.0, 47.1, 50.5, 66.3, 116.6, 138.0, 178.2. IR (neat,

cm^ꢀ1) 2934, 1730, 1482, 1285, 1157, 1036, 995, 924.

LRMS (EI(+)) m/z 212 (M⁺), 182 ([MꢀCH₂O]⁺), 57

(t-Bu, bp). HRMS (EI(+)) calcd for C₁₂H₂₀O₃(M⁺)

212.1412, found 212.1422.

3.6.18. (3R,5S)-5-(tert-Butyldimethylsilyloxy)-3-(tert-butyl-

dimethylsilyloxymethyl)oct-1-en-7-yne (32a). Under an Ar

atmosphere, to a cooled (ꢀ78 ꢁC) solution of diol (8.9 mg,

57.7 lmol), 2,6-lutidine (36 lL, 0.309 mmol) in CH₂Cl₂

(250 lL) was added TBSOTf (36 lL, 0.157 mmol), and

the mixture was stirred at the same temperature for 2 h.

The reaction was quenched by the addition of saturated

aqueous NaHCO₃solution (500 lL), and the mixture was

extracted with AcOEt (2 mL). The organic layer was washed

with brine (2 mL), dried (Na₂SO₄), and concentrated. Puri-

ﬁcation by silica gel column chromatography (hexane/

AcOEt (50:1)) gave the bis-TBS ether 32a (16.8 mg, 76%)

as a colorless oil.

3.6.16. (2R,4S)-2-Vinylhept-6-yne-1,4-diol (31a). To a

cooled (ꢀ78 ꢁC) solution of the epoxide 30a (126.9 mg,

0.598 mmol) in THF (1 mL) was added a solution of

TMS lithium acetylide (0.5 M in hexane/THF, prepared

from TMS–acelylene and n-BuLi, 3.6 mL, 1.8 mmol)

and BF₃ÆOEt₂(114 lL, 0.90 mmol), and stirred at the

same temperature for 1.5 h. The reaction was quenched

by the addition of saturated aqueous NH₄Cl solution

(5 mL), and the mixture was extracted with AcOEt (2·

5 mL). The combined organic layers were washed with

brine (10 mL), dried (Na₂SO₄), and concentrated. The

residue was dissolved in MeOH (2 mL) and cooled on

ice-water bath. NaOMe (28% in MeOH, 345 lL,

1.79 mmol) was added and stirred at room temperature

for 18 h. The reaction was quenched by the addition of

saturated aqueous NH₄Cl solution (3 mL), and the mix-

ture was extracted with AcOEt (4· 5 mL). The com-

bined organic layers were washed with brine (10 mL),

dried (Na₂SO₄), and concentrated. Puriﬁcation by silica

gel column chromatography (AcOEt) gave the diol

(72.8 mg, 79%) as a colorless oil.

21

D

½aꢂ ꢀ26.8ꢁ (c 1.1, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 0.02 (6H, s), 0.06 (3H, s), 0.07 (3H, s), 0.89 (18H,

s), 1.61 (1H, ddd, J = 3.4, 10.3, 13.8 Hz), 1.70 (1H, ddd,

J = 3.7, 8.7, 13.8 Hz), 1.97 (1H, t, J = 2.7 Hz), 2.30 (1H,

ddd, J = 2.7, 7.0, 16.6 Hz), 2.46 (1H, ddd, J = 2.7, 5.0,

16.6 Hz), 2.38 (1H, m), 3.47 (1H, dd, J = 6.6, 9.7 Hz),

3.52 (1H, dd, J = 6.0, 9.7 Hz), 3.83 (1H, dddd, J = 3.4,

5.0, 7.0, 8.7 Hz), 5.01–5.10 (2H, m), 5.63 (1H, ddd,

J = 8.4, 9.6, 18.0 Hz). ¹³C NMR (100 MHz, CDCl₃,

ppm) d ꢀ5.2, ꢀ5.2, ꢀ4.4, ꢀ4.1, 18.1, 18.4, 25.8, 25.9,

26.0, 28.3, 38.2, 42.8, 67.2, 68.9, 70.0, 81.5, 116.0,

139.9. IR (neat, cm^ꢀ1) 3316, 3079, 2932, 1472, 1256,

1100, 837, 776. LRMS (EI(+)) m/z 382 (M⁺), 367

([MꢀMe]⁺), 343 ([MꢀC₃H₃]⁺), 325 ([Mꢀt-Bu]⁺), 257,

211, 193, 147, 73 (bp). HRMS (EI(+)) calcd for

C₂₁H₄₂O₂Si₂(M⁺) 382.2723, found 382.2724.

19

D

1

½aꢂ ꢀ18.8ꢁ (c 0.6, CHCl₃). H NMR (400 MHz, CDCl₃,

ppm) d 1.58 (1H, ddd, J = 3.3, 8.5, 14.2 Hz), 1.64 (1H,

ddd, J = 5.5, 9.2, 14.2 Hz), 2.07 (1H, t, J = 2.7 Hz), 2.16

(2H, br s), 2.36 (1H, ddd, J = 2.7, 6.6, 16.8 Hz), 2.43 (1H,

ddd, J = 2.7, 5.4, 16.8 Hz), 2.53 (1H, m), 3.56 (2H, d,

J = 6.0 Hz), 3.84 (1H, dddd, J = 3.3, 5.4, 6.6, 9.2 Hz),

5.15–5.22 (2H, m), 5.65 (1H, ddd, J = 8.5, 10.5, 16.9 Hz).

¹³C NMR (100 MHz, CDCl₃, ppm) d 28.2, 38.1, 44.1,

66.1, 68.1, 71.0, 80.7, 117.3, 139.0. IR (neat, cm^ꢀ1) 3349,

3303, 3083, 2932, 2120, 1642, 1422, 1065, 1030, 924. LRMS

(EI(+)) m/z 154 (M⁺), 135 ([MꢀH₂OꢀH]⁺), 115

([MꢀC₃H₃]⁺), 97 (bp). HRMS (EI(+)) calcd for C₉H₁₄O₂

(M⁺) 154.0994, found 154.0997.

Compound 32b could also be prepared as in the same

manner (85%) as a colorless oil.

3.6.19. (3S,5S)-5-(tert-Butyldimethylsilyloxy)-3-(tert-butyl-

22

D

dimethylsilyloxymethyl)oct-1-en-7-yne (32b). ½aꢂ +3.8ꢁ (c

1

0.7, CHCl₃). H NMR (400 MHz, CDCl₃, ppm) d 0.03

(6H, s), 0.07 (3H, s), 0.08 (3H, s), 0.88 (9H, s), 0.89 (9H, s),

1.51 (1H, ddd, J = 5.7, 8.8, 13.7 Hz), 1.83 (1H, ddd,

J = 5.6, 7.1, 13.7 Hz), 1.95 (1H, t, J = 2.7 Hz), 2.29 (1H,

m), 2.30 (1H, ddd, J = 2.7, 5.7, 16.8 Hz), 2.37 (1H, ddd,

J = 2.7, 5.7, 16.8 Hz), 3.51 (2H, d, J = 6.0 Hz), 3.86 (1H,

dddd, J = 5.7, 5.7, 5.7, 7.1 Hz), 5.01–5.09 (2H, m), 5.69

(1H, ddd, J = 8.4, 10.4, 17.0 Hz). ¹³C NMR (100 MHz,

CDCl₃, ppm) d ꢀ5.3, ꢀ5.3, ꢀ4.5, ꢀ4.3, 18.2, 18.4, 25.8,

25.9, 26.0, 27.1, 38.1, 42.9, 66.5, 69.1, 69.9, 81.7, 115.5,

140.2. IR (neat, cm^ꢀ1) 3316, 3079, 2930, 2122, 1472, 1256,

1094, 810, 776. LRMS (EI(+)) m/z 382 (M⁺), 367

([MꢀMe]⁺), 343 ([MꢀC₃H₃]⁺), 325 ([Mꢀt-Bu]⁺), 257,

211, 193, 147, 73 (bp). HRMS (EI(+)) calcdfor C₂₁H₄₂O₂Si₂

(M⁺) 382.2723, found 382.2719.

Diol from 30b could also be prepared as in the same

manner (80%) as a colorless oil.

20

D

3.6.17. (2S,4S)-2-Vinylhept-6-yne-1,4-diol (31b). ½aꢂ

ꢀ1.5ꢁ (c 0.4, CHCl₃). ¹H NMR (400 MHz, CDCl₃,

ppm) d 1.67 (1H, ddd, J = 7.6, 7.6, 14.2 Hz), 1.74 (1H,

ddd, J = 4.9, 6.4, 14.2 Hz), 2.02 (2H, br s), 2.07 (1H, t,

J = 2.7 Hz), 2.36 (1H, ddd, J = 2.7, 6.6, 16.6 Hz), 2.45

(1H, ddd, J = 2.7, 4.9, 16.6 Hz), 2.47 (1H, m), 3.56

(1H, dd, J = 6.6, 10.7 Hz), 3.63 (1H, dd, J = 6.0,

10.7 Hz), 3.92 (1H, dddd, J = 4.9, 4.9, 6.6, 7.6 Hz),

5.15–5.21 (2H, m), 5.74 (1H, ddd, J = 8.3, 9.7,

3.6.20. 25-Hydroxy-1b-hydroxymethylvitamin D₃(4a).

Under an Ar atmosphere, a solution of A-ring enyne 32a

(14.8 mg, 38.7 lmol), CD-ring bromooleﬁn 6¹²(58.0 mg,

0.163 mmol), Pd(PPh₃)₄(5.0 mg, 4.3 lmol) in PhMe

S. Honzawa et al. / Bioorg. Med. Chem. 16 (2008) 3002–3024

3023

(200 lL)–Et₃N (200 lL) was stirred at 80 ꢁC for 2 h.

After cooled to room temperature, the mixture was ﬁl-

tered through silica gel pad, washed with PhMe and

AcOEt, and the ﬁltrate was concentrated. The residue

was dissolved in THF (250 lL) and cooled on ice-water

bath. HFÆpy (50 lL) was added and the mixture was stir-

red at the same temperature for 1.5 h and then at room

temperature for 30 min. The mixture was partitioned be-

tween AcOEt (1 mL) and saturated aqueous NaHCO₃

solution (1 mL), and the aqueous layer was extracted

with AcOEt (2 mL). The combined organic layers were

washed with brine (2 mL), dried (Na₂SO₄), and concen-

trated. Puriﬁcation by silica gel column chromatography

(CHCl₃/MeOH (40:1)) gave the product 4a (6.5 mg,

39%) as a pale yellow powder.

lected, suspended in the DMEM supplemented with 5%

FBS (stripped with dextran-coated charcoal) and 1% P/

S without phenol red, and plated in 24-well plate

(2.5 · 10⁴cells/well). Cells were incubated in CO₂incuba-

tor at 37 ꢁC overnight. Ligand stock solutions were pre-

pared at various concentrations in DMSO (10^ꢀ7to

10^ꢀ3M). DMSO itself was used as vesicle. Plasmids used

in our assays were as follows; receptor plasmids

(pM(GAL4-hVDR(DEF)) for wild type hVDR, and

pM(GAL4-hVDR(R274L)(DEF)) for mutant hVDR,

the latter prepared by site-directed mutagenesis using

QuikChange II XL Site-Directed Mutagenesis Kits

(Stratagene)), reporter plasmid (17M2-G-Luc) and inter-

nal standard plasmid (pRL-CMV). Plasmids were diluted

in OPTI-MEM medium at concentrations of 50 ng/well

for receptor plasmid, 0.2 lg/well for reporter plasmid,

and 2.5 ng/well for internal plasmid. Transfections were

carried out by using TransFast reagent (Promega)

according to the manufacturer’s instruction. After 3–6 h

of transfection, ligand stock solutions were added at the

ﬁnal concentrations of 10^ꢀ10to 10^ꢀ6M, and cells were

further incubated overnight. Luciferase assays were per-

formed by using Dual-Luciferase Reporter Assay System

Kit (Promega). All experiments were carried out at least

three times and data were shown as average SD.

23

D

1

½aꢂ ꢀ22.3ꢁ (c 0.1, CHCl₃). H NMR (600 MHz, CDCl₃,

ppm) d 0.54 (3H, s), 0.94 (3H, d, J = 6.7 Hz), 1.02–1.10

(1H, m), 1.22 (6H, s), 1.15–1.76 (17H, m), 1.83–1.92 (2H,

m), 1.96–2.03 (2H, m), 2.13 (1H, dddd, J = 0.8, 3.7, 4.8,

13.5 Hz), 2.33 (1H, dd, J = 6.3, 13.3 Hz), 2.48 (1H, apparent

tt, J = 5.7, 5.7 Hz), 2.59 (1H, dd, J = 3.7, 13.3 Hz), 2.79–

2.86 (1H, m), 3.72 (1H, dd, J = 5.7, 10.9 Hz), 3.78 (1H, dd,

J = 5.7, 10.9 Hz), 4.02 (1H, tt, J = 3.7, 6.3 Hz), 4.99 (1H,

d, J = 1.7 Hz), 5.12 (1H, m), 6.00 (1H, d, J = 11.3 Hz),

6.29 (1H, d, J = 11.3 Hz). ¹³C NMR (150 MHz, CDCl₃,

ppm) d 12.0, 18.8, 20.8, 22.3, 23.6, 27.6, 29.1, 29.2, 29.4,

36.1, 36.4, 37.3, 40.5, 44.2, 44.4, 45.9, 45.9, 56.3, 56.6, 66.4,

68.0, 71.1, 113.1, 117.0, 123.1, 135.0, 143.0, 146.0. IR (ﬁlm,

cm^ꢀ1) 3364, 2942, 1642, 1377, 1034, 911, 760. LRMS

(EI(+)) m/z 430 (M⁺), 412 ([MꢀH₂O]⁺), 400([MꢀCH₂O]⁺),

394 ([Mꢀ2·H₂O]⁺), 381 ([MꢀH₂OꢀCH₂OH]⁺), 363

([Mꢀ2·H₂OꢀCH₂OH]⁺), 135, 59 (bp). HRMS (EI(+))

calcd for C₂₈H₄₆O₃(M⁺) 430.3447, found 430.3440.

Acknowledgments

We are grateful to Ms. Junko Shimode and Ms. Akiko

Tonoki (Teikyo University) for the spectroscopic mea-

surements. We thank Dr. Martin J. Calverley for proof-

reading this manuscript. This work has been supported

in part by Grant-in-Aid from the Ministry of Education,

Culture, Sports, Science and Technology, Japan

(#17790095 to S.H.), and by Grant-in-Aid from Japan

Society for the Promotion of Science (#17590012 to

A.K.). A.K. gratefully acknowledges Uehara Memorial

Foundation.

1a-Hydroxymethylated derivative (4b) could also be pre-

pared as in the same manner (65%) as a white powder.

26

D

1

½aꢂ +83.1ꢁ (c 0.2, CHCl₃). H NMR (600 MHz, CDCl₃,

ppm) d 0.52 (3H, s), 0.93 (3H, d, J = 6.6 Hz), 1.02–1.09

(1H, m), 1.22 (6H, s), 1.19–1.60 (15H, m), 1.62–1.74 (2H,

m), 1.80 (1H, ddd, J = 6.3, 9.0, 12.9 Hz), 1.83–1.90 (1H,

m), 1.90–1.96 (1H, m), 1.96–2.03 (2H, m), 2.27 (1H, dd,

J = 8.1, 12.9 Hz), 2.60 (1H, dd J = 3.9, 12.9 Hz), 2.63 (1H,

m), 2.78–2.84 (1H, m), 3.56–3.64 (2H, m), 4.01 (1H, m),

5.00 (1H, d, J = 2.4 Hz), 5.16 (1H, m), 5.95 (1H, d,

J = 11.4 Hz), 6.32 (1H, d, J = 11.4 Hz). ¹³C NMR

(150 MHz, CDCl₃, ppm) d 11.9, 18.8, 20.8, 22.2, 23.6,

27.7, 29.1, 29.2, 29.3, 36.1, 36.4, 37.4, 40.5, 44.4, 45.9, 46.2,

56.3, 56.5, 64.2, 67.0, 71.1, 113.9, 117.0, 123.7, 134.2,

143.3, 145.4. IR (ﬁlm, cm^ꢀ1) 3312, 2944, 1658, 1632, 1468,

1044, 905, 751. LRMS (EI(+)) m/z 430 (M⁺), 412

([MꢀH₂O]⁺), 400 ([MꢀCH₂O]⁺), 394 ([Mꢀ2·H₂O]⁺), 380

([MꢀH₂OꢀCH₂OHꢀH]⁺), 363 ([Mꢀ2·H₂OꢀCH₂OH]⁺),

135 (bp). HRMS (EI(+)) calcd for C₂₈H₄₆O₃(M⁺)

430.3447, found 430.3449.

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Article Doi

The 2α-(3-hydroxypropyl) group as an active motif in vitamin D3 analogues as agonists of the mutant vitamin D receptor (Arg274Leu)

DOI: 10.1016/j.bmc.2007.12.039

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Authors:

Article abstract of DOI:10.1016/j.bmc.2007.12.039

Full text of DOI:10.1016/j.bmc.2007.12.039

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