A stereodivergent approach to carbahexofuranoses: Synthesis of carba-α-d-glucofuranose, carba-β-d-altrofuranose, carba-α-d-allofuranose, carba-β-d-idofuranose, carba-α-d- galactofuranose and carba-β-d-talofuranose

Article abstract of DOI:10.1016/j.tetlet.2011.08.006

A stereodivergent route, starting from d-glyceraldehyde derivative, employing Wittig olefination-Claisen rearrangement protocol is reported for the synthesis of six novel carbahexofuranoses - carba-α-d-glucofuranose, carba-β-d-altrofuranose, carba-α-d-all

Full text of DOI:10.1016/j.tetlet.2011.08.006

Tetrahedron Letters 52 (2011) 5559–5562
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
A stereodivergent approach to carbahexofuranoses: synthesis
of carba-
a-D-glucofuranose, carba-b-D-altrofuranose, carba-
a-D-allofuranose,
carba-b-D-idofuranose, carba-
a-D-galactofuranose and carba-b-D-talofuranose
⇑
Mukund G. Kulkarni , Ajit S. Borhade, Yunnus B. Shaikh, Attrimuni P. Dhondge, Deekshaputra R. Birhade,
Nagorao R. Dhatrak
Department of Chemistry, University of Pune, Pune, Maharashtra 411 007, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A stereodivergent route, starting from
rearrangement protocol is reported for the synthesis of six novel carbahexofuranoses—carba-a-D
D
-glyceraldehyde derivative, employing Wittig olefination–Claisen
-gluco-
-galactofura-
Received 5 June 2011
Revised 27 July 2011
Accepted 1 August 2011
Available online 7 August 2011
furanose, carba-b-
D
-altrofuranose, carba-
a-D-allofuranose, carba-b-D-idofuranose, carba-a-D
nose and carba-b-
D-talofuranose in enantiomerically pure form.
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Carbasugar
Carbahexofuranose
Claisen rearrangement
Ring closing metathesis
A group of carbohydrate mimetics,1 called carbasugars2 are ob-
tained by replacing ring oxygen atom of a sugar with a methylene
group.3 They have comparatively higher lipophilicity and hence are
potentially beneficial for increasing oral efficiency and cell wall
penetration. Further, due to lack of acetal functionality, the com-
pounds containing carbasugar moiety are more resistant to the
endogenous degradative enzymes. As a consequence of this car-
basugars have higher affinity and selectivity for their cognate
receptors as compared to their natural saccharide counterparts.4
Carbasugars, in their chiral form, can be versatile intermediates
for synthesis of aminocarbasugars,5 carbaoligosaccharides6 and
carba-nucleosides7 (Fig. 1). Carbafuranoses are present as subunits
of natural carbanucleosides, such as aristeromycin8 and neplano-
cin-A9 and synthetic carbanucleosides like Carbovir10 and Cyclara-
dine11 are potent antitumour and antiviral agents. Carbasugars
required for synthesis of such carba-nucleosides are available only
through a complex multistep chiral synthesis.12–15
Several novel and interesting synthetic strategies have been
reported for the synthesis of various carbafuranoses,12 especially,
carbapentofuranoses employing either achiral starting materials13
or chiral substrates like carbohydrates.14 However, only a few ap-
proaches have been reported for the synthesis of carbahexofuranos-
es.15 Therefore, there is enough scope to develop novel, general and
more efficient routes for synthesis of carbahexofuranoses. Such
synthetic routes will be more appealing if they allow the prepara-
tion of all possible stereoisomers of carbahexofuranoses. We herein
report such an approach while achieving the first synthesis of six
isomeric D-carbahexofuranoses.
Wittig olefination of aldehydes or ketones to get allyl vinyl
ethers16 followed by a Claisen rearrangement17 is a convenient
protocol for the generation of 4-pentenals which serve as versatile
synthetic intermediates. Such 4-pentenals have been applied to the
synthesis of terpenes, alkaloids and heterocycles.18 As a part of the
continued interest towards the application of this protocol, a prac-
tical approach for the synthesis of novel carbahexofuranoses has
been designed.
2,3-O-cyclohexylidene-D
-glyceraldhyde19 1 was treated with
allyloxymethylenetriphenylphorane to get the corresponding allyl
vinyl ether 2 (Scheme 1) as an inseparable mixture of E- and
Z-isomers in 1:1.5 ratio. The allyl vinyl ethers 2 underwent Claisen
rearrangement in refluxing xylene to afford aldehyde 3a and 3b as
an inseparable mixture of diastereomers. The ratio of the aldehydes
was estimated to be 1:2.7 fromthe proton NMR spectrum. Reduction
of the diastereomeric mixture of aldehyde 3a and 3b with NaBH4
gave chromatographically separable mixture of alcohols 4a and 4b
in the ratio of 1:2.7. The structures of these alcohols were estab-
lished by converting them to the known alcohols.20,21
Proceeding towards the synthesis of carbahexofuranoses, alco-
hol 4a was oxidized with PCC in CH2Cl2 at 0 °C to aldehyde 3a
½
a 2D9
ꢀ
= ꢁ18.40 (c 6.60, CHCl3) (Scheme 2). Grignard reaction of alde-
⇑
Corresponding author. Tel.: +91 20 25601394; fax: +91 20 25601728.
E-mail address: mgkulkarni@chem.unipune.ac.in (M.G. Kulkarni).
hyde 3a with vinyl magnesium bromide gave the dienol 5a as an
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2011.08.006

5560
M. G. Kulkarni et al. / Tetrahedron Letters 52 (2011) 5559–5562
NH2
N
HO
OH
N
HO
OH
HO
OH
OH
H
H
H
HO
HO
OH
O
OH
N
N
HO
HO
OH
OH
HO OH
HO OH
OH
HO
4a-Carba-α-
5a-Carba-α-
(-)-Aristeromycin
Bis-carbadisaccharide
D-glucofuranose
D-glucopyranose
Figure 1. Structure of carbasugars, carba-nucleoside and carbadisaccharide.
2.51, CHCl3) in 60% yield (Scheme 3). Stereochemical assignment
of the carbasugar derivative 8a was based on NOESY NMR experi-
ment. The NOESY spectrum did not show any NOE correlation
between the protons on carbon C2 and C3 this indicates that the
cis-dihydroxylation of double bond in the cyclopentene benzoate
7a took place exclusively from the opposite face of the alkoxy
groups, which is in accordance with Kishi’s principle.22 The cyclo-
pentene benzoate 7b on dihydroxylation and further protection of
the resulting diol gave the fully protected derivatives of carbahexof-
O
O
a
b
O
O
CHO
O
78%
97%
1
2E:2Z- 1:1.5
O
O
O
O
O
O
c
CHO
HO
HO
96%
uranose 8b ½a 2D9
= ꢁ10.05 (c 6.61, CHCl3) and its diastereoisomer 8c
ꢀ
4a
4b
4a:4b- 1:2.7
½
a 2D9
= +57.09 (c 2.77, CHCl3) in the ratio of 2:1. The stereostructure
ꢀ
3a:3b- 1:2.7
of compound 8c was confirmedby NOESY wherein a NOE correlation
between protons on carbon C-2 and C-3 was observed. This also
established the absolute stereochemistry of the diastereomer 8b.
Following a similar protocol, cyclopentene benzoates 7c and 7d
were transformed to their corresponding carbasugar derivatives.
Cyclopentene benzoate 7c gave exclusively the carbahexofuranose
Scheme 1. Reagents and conditions: (a) CH2CHCH2OCH2Ph3P+Clꢁ, t-BuOꢁNa+, THF,
50–55 °C, 1 h; (b) Xylene, reflux, 6 h; (c) NaBH4, aq Methanol, rt, 35 min.
inseparable mixture of diastereoisomers. This distereomeric mix-
ture of dienol 5a, under ring closing metathesis conditions with
Grubbs’ second generation catalyst, gave a mixture of diastereo-
meric cyclopentenols which on chromatographic separation gave
derivative 8d
½
a 2D9
= +9.22 (c 4.57, CHCl3). The stereochemical
ꢀ
assignment was based on the NOESY NMR experiment and was in
cyclopentenols 6a
½
a 2D9
ꢀ
= ꢁ16.10 (c 0.35, CHCl3) and 6b
accordance with Kishi’s principle.22
½ ꢀ
a 2D9
= +38.66 (c 1.89, CHCl3) in equimolar quantities. Stereochem-
The cyclopentene benzoate 7d gave the fully protected deriva-
tives of carbahexofuranose 8e ½a D29
= ꢁ7.10 (c 1.17, CHCl3) and its
ꢀ
ical assignment to the cyclopentenol 6a was based on the NOESY
NMR experiment, which showed the NOE correlation between pro-
tons on carbon C-1 and C-5. This also established the stereochem-
istry of the cyclopentenol 6b. In a similar fashion the alcohol 4b
diastereomer 8f ½a D29
= ꢁ44.42 (c 6.72, CHCl3) in the ratio of 2:1.
ꢀ
The NOESY NMR spectrum of compound 8f showed NOE correla-
tion between protons on carbon C-2 and C-3. This confirmed the
stereostructure of the compound 8f. This also established the ste-
reostructure of the other diastereomer 8e.
was oxidized to aldehyde 3b ½a D29
ꢀ
= ꢁ5.22 (c 5.86, CHCl3) and con-
verted to the cyclopentenols 6c½a D29
ꢀ
= +16.61 (c 6.54, CHCl3) and 6d
½
a 2D9
ꢀ
= ꢁ48.64 (c 4.50, CHCl3) in 1:1 ratio. In the NOESY NMR spec-
Finally, to complete the synthesis of carbahexofuranoses, the
carbasugar derivatives 8a–8f were treated with NaOH in aqueous
methanol followed by acid mediated hydrolysis of acetals to afford
trum of cyclopentenol 6c, NOE correlation between the protons on
carbon C-1 and C-5 confirmed the stereochemical assignment to
the compound. This also established the stereostructure of cyclo-
pentenol 6d. The hydroxyl group in cyclopentenols 6a–d was pro-
tected as their benzoate esters 7a–d, respectively.
carba-
a
-
D
-glucofuranose 9a ½a D32
ꢀ
= +0.52 (c 2.71, H2O), carba-b-D-
altrofuranose 9b ½a D32
ꢀ
= ꢁ0.27 (c 1.13, H2O), carba-
a-D-allofuranose
9c ½a 3D2
ꢀ
= +3.57 (c 2.68, H2O), carba-b-
D
-idofuranose 9d ½a D32
ꢀ
=
cis-Dihydroxylation of the cyclopentene benzoate 7a using
potassium osmate followed by protection of diol with 2,2-dime-
thoxy propane gave carbasugar derivative 8a
ꢁ10.42 (c 2.34, H2O), carba-
a-D
-galactofuranose 9e ½a D32
= ꢁ2.10
ꢀ
(c 3.34, H2O) and carba-b-
D
-talofuranose 9f ½a D29
= ꢁ7.24 (c 3.36,
ꢀ
½
a 2D9
ꢀ
= ꢁ29.61 (c
H2O), respectively in enantiomerically pure form (Scheme 4).
O
H
O
O
O
4
H
5
1
H
b
a
O
O
O
O
O
c
4a
3
80%
72%
CHO
86%
HO
2
RO
RO
6a:6b
- 1:1
3a
5a
6b
7b
6a R= -H
7a
R= -H
d
92%
d
R= -Bz
R= -Bz
94%
O
O
O
O
H
H
H
a
b
c
O
O
O
4b
89%
80%
CHO
92%
HO
RO
RO
3b
5b
6c:6d - 1:1
d
6d R= -H
7d R= -Bz
6c R= -H
d
7c
90%
R= -Bz
94%
Scheme 2. Reagents and conditions: (a) PCC, CH2Cl2, 0 °C, 4 h; (b) Vinyl magnesium bromide, THF, rt, 20 min; (c) Grubbs’ catalyst second generation, CH2Cl2, rt, 3 h; (d) BzCl,
DABCO, pyridine, CH2Cl2, rt, 6 h.

M. G. Kulkarni et al. / Tetrahedron Letters 52 (2011) 5559–5562
5561
O
O
O
H
4
H
H
a
a
O
O
O
O
O
1
7a
7c
7b
7d
O
O
O
59%
60%
BzO 3 2
O
O
O
BzO
BzO
8a
8b
8c
9:10- 2:1
O
O
H
O
H
a
H
a
O
O
O
O
O
64%
66%
O
O
BzO
BzO
BzO
8d
8e
8f
12 13
: - 2:1
Scheme 3. Reagents and conditions: (a) (i) K2OsO4, NMO, aq THF, rt, 10 h; (ii) 2,2-dimethoxy propane, p-TSA, CH2Cl2, rt, 20 min.
HO
HO
HO
H
H
H
H
H
HO
HO
HO
OH
OH
OH
OH
OH
OH
a
a
a
8a
8d
8b
8e
8c
8f
HO
HO
HO
68%
62%
55%
9a
9b
9c
HO
HO
HO
HO
HO
H
HO
OH
OH
OH
OH
a
a
a
OH
OH
HO
HO
HO
59%
56%
53%
9d
9e
9f
Scheme 4. Reagents and conditions: (a) (i) NaOH, aq Methanol, rt, 15 min; (ii) Concd HCl, aq Methanol, rt, 12 h.
5. (a) Shealy, Y. F.; O’Dell, C. A. Tetrahedron Lett. 1969, 10, 2231–2234; (b) Shealy,
Y. F.; Clayton, J. D. J. Am. Chem. Soc. 1969, 91, 3075–3083; (c) Arita, M.; Adachi,
K.; Ito, Y.; Sawai, H.; Ohno, M. J. Am. Chem. Soc. 1983, 105, 4049–4055; (d)
Leroy, E.; Reymond, J.-L. Org. Lett. 1999, 1, 775–777; (e) Vince, R.; Brownell, J.;
Daluge, S. J. Med. Chem. 1984, 27, 1358–1360; (f) Domínguez, B. M.; Cullis, P. M.
Tetrahedron Lett. 1999, 40, 5783–5786.
6. (a) Ogawa, S.; Matsunaga, N.; Li, H.; Palcic, M. M. Eur. J. Org. Chem. 1999, 3, 631–
642; (b) Ogawa, S.; Furuya, T.; Tsunoda, H.; Hindsgaul, O.; Stangier, K.; Palcic,
M. M. Carbohydr. Res. 1995, 271, 197–205; (c) Frigell, J.; Cumpstey, I.
Tetrahedron Lett. 2009, 50, 5142–5144.
In conclusion, we have achieved synthesis of six novel carbah-
exofuranoses from -glyceraldehyde derivative by applying Wittig
olefination–Claisen rearrangement protocol. These carbahexofura-
noses could serve as chiral pool substrates for the synthesis of di-
verse carba-nucleosides and related analogues.
D
Acknowledgment
7. (a) Shealy, Y. F.; Clayton, J. D. J. Am. Chem. Soc. 1966, 88, 3587–3885; For review
articles on the carbocyclic nucleoside, see: (b) Agrofoglio, L.; Suhas, E.; Farese,
A.; Condom, R.; Challand, S. R.; Earl, R. A.; Guedj, R. Tetrahedron 1994, 50,
10611–10670; (c) Borthwick, A. D.; Biggadike, K. Tetrahedron 1992, 48, 571–
632; (d) Marquez, V. E.; Lim, M.-I. Med. Res. Rev. 1986, 6, 1–40; (e) Jenkins, G.
N.; Turner, N. J. Chem. Soc. Rev. 1995, 24, 169–176; (f) Crimmins, M. T.
Tetrahedron 1998, 54, 9229–9272; (g) Ferrero, M.; Gotor, V. Chem. Rev. 2000,
100, 4319–4348.
8. (a) Kusaka, T.; Yamomoto, H.; Shibata, M.; Muroi, M.; Kishi, T.; Mizuno, K. J.
Antibiot. 1967, 21, 255–263; (b) Kishi, T.; Muroi, M.; Kusaka, T.; Nishikawa, M.;
Kamiya, K.; Mizuno, K. Chem. Pharm. Bull. 1972, 20, 940–946; (c) Wolfe, M. S.;
Borcherding, D. R.; Borchardt, R. T. Tetrahedron Lett. 1989, 30, 1453–1456; (d)
Wolfe, M. S.; Anderson, B. L.; Borcherding, D. R.; Borchardt, R. T. J. Org. Chem.
1990, 55, 4712–4717.
9. (a) Hayashi, M.; Yaginuma, S.; Yoshioka, H.; Nakatsu, K. J. Antibiot. 1981, 34,
675–680; (b) Yaginuma, S.; Muto, N.; Tsujino, M.; Sudate, Y.; Hayashi, M.;
Otani, M. J. Antibiot. 1981, 34, 359–366; (c) DeClercq, E.; Cools, M.; Balzarini, J.;
Marquez, V. E.; Borcherding, D. R.; Borchardt, R. T.; Drach, J. C.; Kitaoka, S.;
Konno, T. Antimicrob. Agents Chemother. 1989, 33, 1291–1297; (d) Borcherding,
D. R.; Scholtz, S. A.; Borchardt, R. T. J. Org. Chem. 1987, 52, 5457–5461.
10. (a) Vince, R.; Hua, M. J. Med. Chem. 1990, 33, 17–21; (b) Trost, B. M.; Madsen, R.;
Guile, S. G.; Elia, A. E. H. Angew. Chem., Int. Ed. Engl. 1996, 35, 1569–1572; (c)
Roberts, S. M.; Shoberu, K. A. J. Chem. Soc., Perkin Trans. 1 1991, 2605–2607; (d)
Nokami, J.; Matsuura, H.; Nakasima, K.; Shibata, S. Chem. Lett. 1994, 1071–
1074.
Authors A.S.B., Y.B.S., A.P.D. and D.R.B. thank CSIR, New Delhi for
research fellowship.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2011.08.006.
References and notes
1. (a)Carbohydrate Mimics. Concepts and Methods; Chapleur, Y., Ed.; Wiley-VCH:
Weinheim, New York, 1998; (b) Sears, P.; Wong, C.-H. Angew. Chem., Int. Ed.
1999, 38, 2300–2324; (c) Kitov, P. I.; Sadowska, J. M.; Mulvey, G.; Armstrong, G.
D.; Ling, H.; Pannu, N. S.; Read, R. J.; Bundle, D. R. Nature 2000, 403, 669–672;
(d) Sears, P.; Wong, C.-H. Science 2001, 291, 2344–2350.
2. (a) Joint Commission on Biochemical Nomenclature (McNaught A. D.) Pure
Appl. Chem. 1996, 68, 1919-2008.; (b) Suami, T. Top. Curr. Chem. 1990, 154, 257–
283.
3. (a) McCasland, G. E.; Furuta, S.; Durham, L. J. J. Org. Chem. 1966, 31, 1516–
1521; (b) McCasland, G. E.; Furuta, S.; Durham, L. J. J. Org. Chem. 1968, 33,
2835–2841; (c) McCasland, G. E.; Furuta, S.; Durham, L. J. J. Org. Chem. 1968,
33, 2841–2844.
4. (a) Desgranges, C.; Razaka, G.; Rabaud, M.; Bricaud, H.; Balzarini, J.; DeClerq, E.
Biochem. Pharmacol. 1983, 32, 3583–3590; (b) Herdewijn, P.; Balzarini, J.;
DeClercq, E.; Vanderhaeghe, H. J. Med. Chem. 1985, 28, 1385–1386; (c)
DeClercq, E.; Balzarini, J.; Bernaerts, R.; Herdewijn, P.; Verbruggen, A.
Biochem. Biophys. Res. Cornmun. 1985, 126, 397–403; (d) De Clercq, E.
Nucleosides Nucleotides 1998, 17, 625–634; (e) Wachtmeister, J.; Classon, B.;
Samuelsson, B.; Kvarnström, I. Tetrahedron 1995, 51, 2029–2038; (f)
Wachtmeister, J.; Classon, B.; Samuelsson, B.; Kvarnström, I. Tetrahedron
1997, 53, 1861–1872.
11. (a) Yoshikawa, M.; Yokokawa, Y.; Inoue, Y.; Yamaguchi, S.; Murakami, N.;
Kitagawa, I. Tetrahedron 1994, 50, 9961–9974; (b) Katagiri, N.; Matsuhashi, Y.;
Kokufuda, H.; Takebayashi, M.; Kaneko, C. Tetrahedron Lett. 1997, 38, 1961–
1964.
12. Review articles for synthesis of carbasugars (a) Ferrier, R. J.; Middleton, S.
Chem. Rev. 1993, 93, 2779–2831; (b) Arjona, O.; Gómez, A. M.; López, J. C.;
Plumet, J. Chem. Rev. 2007, 107, 1919–2036; (c) Plumet, J.; Gómez, A. M.; López,
J. C. Mini-Rev. Org. Chem. 2007, 4, 201–216.
13. (a) Marschner, C.; Baumgartner, J.; Griengl, H. J. Org. Chem. 1995, 60, 5224–
5235; (b) Neufellner, E.; Kapeller, H.; Griengl, H. Tetrahedron 1998, 54, 11043–

5562
M. G. Kulkarni et al. / Tetrahedron Letters 52 (2011) 5559–5562
11062; (c) Shoberu, K. A.; Roberts, S. M. J. Chem. Soc., Perkin Trans. 1 1992,
Dhondge, A. P.; Borhade, A. S.; Chavhan, S. W.; Gaikwad, D. D. Tetrahedron Lett.
2006, 47, 1003–1005; (f) Kulkarni, M. G.; Davawala, S. I.; Shinde, M. P.;
Dhondge, A. P.; Borhade, A. S.; Chavhan, S. W.; Gaikwad, D. D. Tetrahedron Lett.
2006, 47, 3027–3029; (g) Kulkarni, M. G.; Dhondge, A. P.; Borhade, A. S.;
Gaikwad, D. D.; Chavhan, S. W.; Shaikh, Y. B.; Ningdale, V. B.; Desai, M. P.;
Birhade, D. R.; Shinde, M. P. Tetrahedron Lett. 2009, 50, 2411–2413; (h)
Kulkarni, M. G.; Dhondge, A. P.; Borhade, A. S.; Gaikwad, D. D.; Chavhan, S. W.;
Shaikh, Y. B.; Ningdale, V. B.; Desai, M. P.; Birhade, D. R.; Shinde, M. P. Eur. J. Org.
Chem. 2009, 23, 3875–3877.
2419–2425; (d) Saville-Stones, E. A.; Lindlell, S. D.; Jennings, N. S.; Head, J. C.;
Ford, M. J. J. Chem. Soc., Perkin Trans. 1 1991, 2603–2604; (e) Henly, R.; Elie, C. J.
J.; Buser, H. P.; Ramos, G.; Moser, H. E. Tetrahedron Lett. 1993, 34, 2923–2926;
(f) Shuto, S.; Shirato, M.; Sumita, Y.; Ueno, Y.; Matsuda, A. J. Org. Chem. 1998, 63,
1986–1994; (g) Gathergood, N.; Knudsen, K. R.; Jørgensen, K. A. J. Org. Chem.
2001, 66, 1014–1017; (h) Rassu, G.; Auzzas, L.; Pinna, L.; Zambrano, V.;
Battistini, L.; Zanardi, F.; Marzocchi, L.; Acquotti, D.; Casiraghi, G. J. Org. Chem.
2001, 66, 8070–8075; (i) Caddick, S.; Cheung, S.; Doyle, V. E.; Frost, L. M.;
Soscia, M. G.; Delisser, V. M.; Williams, M. R. V.; Etheridge, Z. C.; Khan, S.;
Hitchcock, P. B.; Pairaudeau, G.; Vile, S. Tetrahedron 2001, 57, 6295–6303.
14. (a) Tadano, K.-I.; Maeda, H.; Hoshino, M.; Iimura, Y.; Suami, T. J. Org. Chem.
1987, 52, 1946–1956; (b) Tadano, K.-I.; Hoshino, M.; Ogawa, S.; Suami, T. J. Org.
Chem. 1988, 53, 1427–1432; (c) Mishra, G. P.; Ramana, G. V.; Rao, B. V. Chem.
Commun. 2008, 3423–3425; (d) Yoshikawa, M.; Cha, B. C.; Okaichi, Y.;
Kitagawa, I. Chem. Pharm. Bull. 1988, 36, 3718–3721; (e) Johansen, S. K.;
Lundt, I. J. Chem. Soc., Perkin Trans. 1 1999, 3615–3622; (f) Matsugi, M.;
Gotanda, K.; Ohira, C.; Suemura, M.; Sano, A.; Kita, Y. J. Org. Chem. 1999, 64,
6928–6930; (g) Chénedé, A.; Pothier, P.; Sollogoub, M.; Fairbanks, A. J.; Sinaÿ, P.
J. Chem. Soc., Chem. Commun. 1995, 1373–1374; (h) Désiré, J.; Prandi, J. Eur. J.
Org. Chem. 2000, 3075–3084; (i) Callam, C. S.; Lowary, T. L. J. Org. Chem. 2001,
66, 8961–8972.
19. Sugiyama, T.; Sugawara, H.; Watanabe, M.; Yamashita, K. Agric. Biol. Chem.
1984, 48, 1841–1844.
20. The stereochemical assignment of the newly generated chiral centre in the
alcohol 4a and 4b was established by converting them separately to the known
alcohols (+)-10 and (ꢁ)-10, respectively and then matching their specific
optical rotations with reported values.21 (+)-10 ½a D29
ꢀ
= +11.60 (c 0.68, CHCl3)
[Lit.21
½
a 2D2
ꢀ
= +13.6 (c 0.92, CHCl3)]. (ꢁ)-10 ½a D29
ꢀ
= ꢁ8.60 (c 0.68, CHCl3) [Lit.21
½ ꢀ = ꢁ12.1 (c 0.68, CHCl3)]. Hence the stereochemistry at newly created
a 2D2
chiral centre in alcohol 4a was assigned as ‘S’ while that in alcohol 4b was
assigned as ‘R’.
15. (a) Horneman, A. M.; Lundt, I. J. Org. Chem. 1998, 63, 1919–1928; (b)
Horneman, A. M.; Lundt, I. Synthesis 1999, 317–325; (c) Ghosh, S.; Bhaumik,
T.; Sarkar, N.; Nayek, A. J. Org. Chem. 2006, 71, 9687–9694; (d) Frigell, J.;
Cumpstey, I. Tetrahedron Lett. 2007, 48, 9073–9076.
16. Kulkarni, M. G.; Pendharkar, D. S.; Rasne, R. M. Tetrahedron Lett. 1997, 38,
1459–1462.
(S)
(R)
HO
HO
OBn
(-)-10
OBn
(+)-10
17. Kulkarni, M. G.; Davawala, S. I.; Doke, A. K.; Pendharkar, D. S. Synthesis 2004,
2919–2926.
18. (a) Kulkarni, M. G.; Pendharkar, D. S. J. Chem. Soc., Perkin Trans. 1 1997, 21,
3127–3128; (b) Kulkarni, M. G.; Pendharkar, D. S. Tetrahedron 1997, 53, 3167–
3172; (c) Kulkarni, M. G.; Rasne, R. M. J. Chem. Soc., Perkin Trans. 1 1998, 16,
2479–2480; (d) Kulkarni, M. G.; Rasne, R. M.; Davawala, S. I.; Doke, A. K.
Tetrahedron Lett. 2002, 43, 2297–2298; (e) Kulkarni, M. G.; Davawala, S. I.;
21. Fukuyama, T.; Wang, C.-L. J.; Kishi, Y. J. Am. Chem. Soc. 1979, 101, 260–262.
22. Cha, J. K.; Christ, W. J.; Kishi, Y. Tetrahedron 1984, 40, 2247–2255.