Tetra hydrozerumbone 2, which has a powerful balmy fragrance, has a stereogenic carbon at C2 and can be easily prepared from zerumbone 1, which is one of the most important materials that displays ail NMRDOS character. Reduction of 2 gave two diastereomers 3 and 4: their optically active (>99% ee) alcohols were obtained by lipase-catalyzed stereoselective transesterification of each racemic alcohol. The enantioselectivity of tetrahydrozerumbol does not entirely depend on the hydroxyl position but on the 2-methyl position Compounds (R)-2 and (S)-2 were obtained by Dess- Martin oxidation of the corresponding alcohols. Interestingly, (R)-2 showed a strong balmy fragrance while (S)-2 had hardly any fragrance (c) 2009 Elsevier Ltd. All rights reserved.
Efficient synthesis of an optically active tetrahydrozerumbone exhibiting a fragrance and the application of zerumbone derivatives with a medium ring structure
摘要:
(R)-Tetrahydrozerumbone 2, which has a powerful balmy fragrance, contains a stereogenic carbon at the C2 position and can be easily prepared from zerumbone 1, one of the most important materials displaying an NMRDOS character. The reduction of 2 gave two diastereomers of tetrahydrozerumbol 3, and the optically active (>99%ee) alcohols were obtained by a lipase-catalyzed stereoselective transesterification of each racemic alcohol. A barrier to this development is a long reaction time (about four weeks) and the need to separate the diastereoisomers. The desired (2R)-form of 3 was efficiently obtained by a lipase-catalyzed transesterification under optimized conditions using a diastereomeric mixture of racemic 3 as the starting material without separation of the diastereomers. Using this method, the reaction of other zerumbone derivatives is greatly improved. (C) 2012 Elsevier Ltd. All rights reserved.