申请人:——
公开号:US20020028958A1
公开(公告)日:2002-03-07
The present invention provides a simplified and convenient process for the preparation of an optically active enone such as 7,7-dimethyl-6,8-dioxabicyclo-[3,3,0]oct-3-en-2-one.
The invention further provides novel optically active intermediate compounds.
The process for the preparation of an optically active enone represented by the formula (4) comprises steps of (A) deprotecting the protecting group for the hydroxyl group at the 1-position in a compound represented by the formula (1) to a hydroxyl group (compound (2)), (B) oxidizing the hydroxyl group to a ketone group (compound (3)) and (C) deprotecting the protecting group for the hydroxyl group at the 4-position to form a double bond between the carbon atom at the 4-position and the carbon atom at the 5-position, according to the following reaction schemes:
1
wherein R
1
and R
4
independently represent a cumyl group, &agr;,&agr;-diethylbenzyl, &agr;,&agr;-dimethyl-p-methoxybenzyl, t-butyldimethylsilyl, trimethylsilyl, triethylsilyl, triisopropylsilyl, isopropyldimethylsilyl or ethyldimethylsilyl, R
2
and R
3
jointly represent acetonide, methyl ethyl ketal or diethyl ketal, and R
5
represents a hydrogen atom, an alkyl group having not more than 20 carbon atoms or a phenyl group.
本发明提供了一种制备光学活性烯酮(如 7,7-二甲基-6,8-二氧双环-[3,3,0]辛-3-烯-2-酮)的简便工艺。
本发明进一步提供了新型光学活性中间体化合物。
制备式(4)所代表的光学活性烯酮的工艺包括以下步骤 (A) 将式(1)所代表的化合物中 1 位羟基的保护基脱保护成羟基(化合物(2))、(B) 将羟基氧化为酮基(化合物(3)),以及 (C) 根据以下反应方案,将 4 位羟基的保护基脱保护,以在 4 位碳原子和 5 位碳原子之间形成双键:
1
其中 R
1
和 R
4
独立地代表一个积基、&agr;,&agr;-二乙基苄基、&agr;,&agr;-二甲基对甲氧基苄基、叔丁基二甲基硅基、三甲基硅基、三乙基硅基、三异丙基硅基、异丙基二甲基硅基或乙基二甲基硅基,R
2
和 R
3
共同代表丙酮、甲基乙基缩酮或二乙基缩酮,以及 R
5
代表氢原子、碳原子数不超过 20 个的烷基或苯基。