Synthetic Studies on Oligomycins. Synthesis of the Oligomycin B Spiroketal and Polypropionate Portions
作者:Masaya Nakata、Takashi Ishiyama、Shinichi Akamatsu、Youichi Hirose、Hiroshi Maruoka、Rika Suzuki、Kuniaki Tatsuta
DOI:10.1246/bcsj.68.967
日期:1995.3
The oligomycin B spiroketal portion, [2S,2(2R),3S,6R,8S,8(3R),9S,10R,11S]-2-[2-(t-butyldiphenylsilyloxy)propyl]-8-[3-(hydroxymethyl)pentyl]-3,9,11-trimethyl-1,7-dioxaspiro[5.5]undecane-5,10-diol (2), and polypropionate portion, ethyl (2E,4S,5R,6R,7S,8S,9R,10S,12R,13S,14R,16E)-5-(t-butyldimethylsilyloxy)7,9-(isopropylidenedioxy)-12,13-(4-methoxybenzylidenedioxy)-4,6,8,10,12,14-hexamethyl-11-oxo-18-phenylsulfonyloctadeca-2,16-dienoate (3), have been synthesized. The C19-C21 Wittig salt, [(2S,3R)-2-ethyl-3,4-(isopropylidenedioxy)butyl]triphenylphosphonium iodide (6), prepared from 2-butene-1,4-diol via Sharpless epoxidation, was coupled with the C22-C27 aldehyde, benzyl 2,4-dideoxy-3-O-(4-methoxybenzyl)-2,4-di-C-methyl-α,β-l-galacto-hexodialdopyranoside-(1,5) (7), prepared from (Z)-2-butene-1,4-diol via Sharpless epoxidation and the Brown’s crotylboration. The resulting coupling product was transformed to the C19-C27 lactone, [3S,4R,5R,6S,6(3R,4R)]-6-[3-ethyl-4,5-(isopropylidenedioxy)pentyl]-4-(4-methoxybenzyloxy)-3,5-dimethyl-3,4,5,6-tetrahydro-2H-pyran-2-one (4). The C28-C34 organostannane compound, (2R,4S,5S,7RS)-2-(t-butyldiphenylsilyloxy)-5-methyl-7-(tributylstannyl)-4-(triethylsilyloxy)-7-[(2-trimethylsilylethoxy)methoxy]heptane (5b), was prepared from (R)-methyl 3-hydroxybutyrate via the Brown’s crotylboration and the Still’s stannylation. After lithiation of 5b with butyllithium, the resulting α-alkoxy organolithium compound was coupled with 4 and the product was converted to the C19-C34 spiroketal, [2S,2(2R),3S,6R,8S,8(3R,4R),9S,10R,11S]-2-[2-(t-butyldiphenylsilyloxy)propyl]-8-[3-ethyl-4,5-(isopropylidenedioxy)pentyl]-10-(4-methoxybenzyloxy)-3,9,11-trimethyl-1,7-dioxaspiro[5.5]undecan-5-ol (37). The synthetic 2, derived from 37, was identical to the oligomycins (A, B, C mixture) degradation product in all respects, which elucidates the absolute stereochemistry of oligomycin B (1b). The C3-C9 aldehyde, (2-trimethylsilylethoxy)methyl 2,4,6-trideoxy-3-O-(4-methoxybenzyl)-2,4,6-tri-C-methyl-d-glycero-α-l-ido-heptodialdopyranoside-(1,5) (9), was prepared from (2S)-3-(t-butyldimethylsilyloxy)-2-methylpropanal via Keck’s crotylstannane addition and Brown’s crotylboration. The aldol coupling between the zinc enolate of the C10-C16 ketone, t-butyldimethylsilyl 2,3,7,8-tetradeoxy-4-O-(4-methoxybenzyl)-3,5-di-C-methyl-α-l-xylo-octopyranosid-6-ulose (10), prepared from methyl (R)-(+)-lactate via Brown’s crotylboration and a metallated methoxyallene addition, and aldehyde 9 gave the C8-C9 syn, C9-C10 syn product, which was transformed to the oligomycin B polypropionate portion 3 through elongation of the C1-C2 and C17-C18 carbon units.
寡霉素 B 螺酮部分,[2S,2(2R),3S,6R,8S,8(3R),9S,10R,11S]-2-[2-(叔丁基二苯基硅氧基)丙基]-8-[3-(羟甲基)戊基]-3,9,11-三甲基-1,7-二氧杂螺[5.5]十一烷-5,10-二醇 (2),以及聚丙酸乙酯部分,(2E,4S,5R,6R,7S,8S,9R,10S,12R,13S,14R,16E)-5-(叔丁基二甲基硅氧基)7、9-(异亚丙基二氧基)-12,13-(4-甲氧基亚苄基二氧基)-4,6,8,10,12,14-六甲基-11-氧代-18-苯磺酰基十八碳-2,16-二烯酸酯 (3) 的合成。由 2-丁烯-1,4-二醇通过 Sharpless 环氧化反应制备的 C19-C21 Wittig 盐[(2S,3R)-2-乙基-3,4-(异丙基亚二氧基)丁基]三苯基碘化鏻(6)与 C22-C27 醛偶联、苄基 2,4-二脱氧-3-O-(4-甲氧基苄基)-2,4-二-C-甲基-α,β-半乳-己二酰吡喃糖苷-(1,5) (7),由 (Z)-2 丁烯-1,4-二醇通过 Sharpless 环氧化反应和布朗羰基硼化反应制备。得到的偶联产物转化为 C19-C27 内酯,[3S,4R,5R,6S,6(3R,4R)]-6-[3-乙基-4,5-(异亚丙基二氧基)戊基]-4-(4-甲氧基苄氧基)-3,5-二甲基-3,4,5,6-四氢-2H-吡喃-2-酮(4)。C28-C34有机锡化合物(2R,4S,5S,7RS)-2-(叔丁基二苯基硅氧基)-5-甲基-7-(三丁基锡烷基)-4-(三乙基硅氧基)-7-[(2-三甲基硅乙氧基)甲氧基]庚烷(5b)是由(R)-3-羟基丁酸甲酯通过布朗羰基硼化和斯蒂尔烷基化反应制备的。5b 与丁锂发生石化作用后,得到的 α-烷氧基有机锂化合物与 4 发生偶联反应,产物转化为 C19-C34 螺酮醛 [2S、2(2R),3S,6R,8S,8(3R,4R),9S,10R,11S]-2-[2-(t-butyldiphenylsilyloxy)propyl]-8-[3-ethyl-4,5-(isopropylidenedioxy)pentyl]-10-(4-methoxybenzyloxy)-3,9,11-trimethyl-1,7-dioxaspiro[5.5]十一烷-5-醇(37)。从 37 中合成的 2 在所有方面都与低聚霉素(A、B、C 混合物)的降解产物相同,从而阐明了低聚霉素 B(1b)的绝对立体化学结构。C3-C9 醛,(2-三甲基甲硅烷氧基)甲基 2,4,6-三脱氧-3-O-(4-甲氧基苄基)-2,4,6-三-C-甲基-d-甘油-α-l-ido-heptodialdopyranoside-(1,5) (9),是由(2S)-3-(t-丁基二甲基甲硅烷氧基)-2-甲基丙醛通过 Keck 的巴豆烷加成法和 Brown 的巴豆烷硼化法制备的。C10-C16 酮、2,3,7,8-四甲氧基-4-O-(4-甲氧基苄基)-3,5-二-C-甲基-α-叔丁氧羰基吡喃糖苷-6-酮的烯酸锌之间的醛醇偶联(10)、由(R)-(+)-乳酸甲酯通过布朗羰基硼化和金属化甲氧基烯加成法制备,并与醛 9 反应得到 C8-C9 syn、C9-C10 syn 产物,该产物通过 C1-C2 和 C17-C18 碳单元的伸长转化为寡霉素 B 聚丙酸酯部分 3。