Li/K-derivative 6 is used to synthesize the title compounds (3a and 4a) in enantiomerically pure form from (−)-(S)-propylene epoxide. The C,C bond forming key step leading to the hydroxyketone 7 is followed by cyclization (, 8), Beckmann cleavage ( 9b) and hydrolysis to 3a (recently isolated from civet). Base treatment of 3a opens the ring (10) to give the hydroxyacid 1 which is cyclized to the macrolide
Li / K衍
生物6用于从(-)-(S)-环氧
丙烷合成对映体纯形式的标题化合物(3a和4a)。导致羟基酮7的C,C键形成关键步骤是环化(,8),贝克曼裂解(9b)和
水解为3a(最近从麝猫中分离)。3a的碱处理打开环(10),得到羟基酸1,该羟基酸1被环化成大环内酯4a。高度亲核的双还原二烯酮系统6的合成有用性d 5因此证明了-试剂(参见合成子2)。