Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H
作者:Ludovic Raffier、Olivier Piva
DOI:10.3762/bjoc.7.21
日期:——
The asymmetric synthesis of gymnastatin H has been achieved by using the photoisomerisation of a conjugated ester to its beta,gamma-unsaturated isomer through the protonation of a in situ generated dienol as key step. Thanks to diacetone D-glucose used as a chiral alkoxy group, the protonation occurred well onto one of the two diastereotopic faces with very high yields and selectivities. Moreover,
Gynastatin H 的不对称合成是通过使用共轭酯的光异构化为其 β,γ-不饱和异构体通过原位生成的二烯醇的质子化作为关键步骤来实现的。由于双丙酮D-葡萄糖用作手性烷氧基,质子化以非常高的产率和选择性很好地发生在两个非对映体之一上。此外,通过这种方式控制了目标分子的 C-6 中心的构型。
Establishment of Relative and Absolute Configurations of Phaeosphaeride A: Total Synthesis of <i>ent</i>-Phaeosphaeride A
The relative and absolute configurations of phaeosphaeride A have been established via the first total synthesis of ent-phaeosphaeride A. The three contiguous stereogenic centers were installed by Sharpless asymmetric dihydroxylation and a stereoselective intramolecular vinyl anion aldol reaction. This synthesis has altered the originally proposed structure of natural phaeosphaeride A.
Novel dioctatin derivatives and production process thereof
申请人:Muraoka Yasuhiko
公开号:US20080312080A1
公开(公告)日:2008-12-18
To provide dioctatin derivatives, a production process thereof, an aflatoxin production inhibitor containing the dioctatin derivative, and a method of controlling aflatoxin contamination by use of the aflatoxin production inhibitor containing the dioctatin derivative. The present invention provides dioctatin derivatives represented by the following Structural Formula (I):
where R
1
and R
2
each represent CH
3
—(CH
2
)
n
—, (CH
3
)
2
CH—CH
2
— or C
6
H
5
—CH
2
—; n represents an integer of 2 to 6; X
1
and X
2
each represent CH
3
or hydrogen atom; and Y represents 2-amino-2-butenoic acid or amino acid residue, with compounds where R
1
and R
2
are each CH
3
(CH
2
)
4
—, X
2
is a hydrogen atom and Y is 2-amino-2-butenoic acid being excluded.
The first total synthesis of the proposed structure of phaeosphaeride A has been achieved via six-membered-ring formation by means of an intramolecular vinyl-anion aldol reaction as the key step. This synthesis suggests a revised configurational assignment for phaeosphaeride A.