作者:Takamitsu Sasaki、Keisuke Kato、Hiroyuki Akita
DOI:10.1248/cpb.52.770
日期:——
Palladium-catalyzed cyclization-methoxycarbonylation of (2R,3S)-3-methylpenta-4-yne-1,2-diol (6) derived from (2R,3S)-epoxy butanoate 5, followed by methylation, gave the tetrahydro-2-furylidene acetate (−)-7, which was converted to the left-half aldehyde (+)-3. A Wittig reaction between (+)-3 and the phosphoranylide derived from the bithiazole-type phosphonium iodide 4 using lithium bis(trimethylsilyl)amide afforded (+)-cystothiazole B (2), the spectral data of which were identical to those of the natural product (+)-2. Thus the stereochemistry of cystothiazole B (2) was confirmed to be [4R, 5S, 6(E)].
(2R,3S)-3-甲基-4-戊炔-1,2-二醇(6)由(2R,3S)-环氧丁酸酯5衍生而来,经钯催化环化-甲氧基羰基化,然后甲基化,得到四氢-2-呋喃亚基乙酸酯(-)-7,后者转化为左半部分醛(+)-3。(+)-3与双噻唑型碘化磷鎓衍生的磷酰亚胺4之间发生Wittig反应,使用双(三甲基硅烷基)胺锂,得到(+)-胱硫杂噻唑B(2),其光谱数据与天然产物(+)-2完全一致。因此,胱硫杂噻唑B(2)的立体化学结构被确认为[4R,5S,6(E)]。