Synthetic Studies of Venturicidins. Synthesis of the C1–C14 Segment of Venturicidins
作者:Masaya Nakata、Junji Ohashi、Kunihiko Ohsawa、Toru Nishimura、Mitsuhiro Kinoshita、Kuniaki Tatsuta
DOI:10.1246/bcsj.66.3464
日期:1993.11
The C1–C14 segment of venturicidins, (2R,6R)-3,6-dihydro-6-[(E)-7-(dimethoxyphosphinyl)-1-methyl-6-oxo-1-heptenyl]-2-methoxy-5-methyl-2H-pyran-2-acetic acid (1), has been synthesized. The C8–C13 segment of venturicidins, (E)-2-bromo-7-(4,4′-dimethoxytriphenylmethoxy)-2-heptene (2), was lithiated with t-butyllithium and the resulting vinyllithium compound was coupled with the C1–C7 segment, (2Z,7S)-7-(t-butyldimethylsilyloxy)-8-(t-butyldiphenylsilyloxy)-2-methyl-5,5-(trimethylenedithio)-2-octenal (4), to afford the alcohol. A subsequent seven-step conversion of this alcohol furnished the synthesis of the C1–C13 segment, (2R,6R)-3,6-dihydro-6-[(E)-6-hydroxy-1-methyl-1-hexenyl]-2-methoxy-5-methyl-2H-pyran-2-acetate (9). Finally, the known four-step transformation led 9 to the target compound 1.
(2R,6R)-3,6-二氢-6-[(E)-7-(二甲氧基膦酰基)-1-甲基-6-氧代-1-庚烯基]-2-甲氧基-5-甲基-2H-吡喃-2-乙酸 (1) 的文曲星素 C1-C14 段已被合成。文曲星的 C8-C13 段,(E)-2-溴-7-(4,4′-二甲氧基三苯甲氧基)-2-庚烯 (2) 与 t-丁基锂发生锂化反应,得到的乙烯基锂化合物与 C1-C7 段发生偶联反应、(2Z,7S)-7-(叔丁基二甲基硅氧基)-8-(叔丁基二苯基硅氧基)-2-甲基-5,5-(三亚甲基二硫代)-2-辛烯醛 (4),得到醇。随后,通过对该醇进行七步转化,合成了 C1-C13 段的 (2R,6R)-3,6-二氢-6-[(E)-6-羟基-1-甲基-1-己烯基]-2-甲氧基-5-甲基-2H-吡喃-2-乙酸酯 (9)。最后,通过已知的四步转化,9 得到了目标化合物 1。