Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with N-gulosyl nitrones
作者:Osamu Tamura、Kodai Takeda、Naka Mita、Masanori Sakamoto、Iwao Okamoto、Nobuyoshi Morita、Hiroyuki Ishibashi
DOI:10.1039/c1ob06067h
日期:——
Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with L-gulose-derived chiral nitrones in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate was investigated. The selectivity was strongly influenced by the bulkiness of the C-substituent of the nitrone: for example, C-benzyloxymethyl nitrone afforded four stereoisomers, whereas bulky C-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]nitrone gave a single stereoisomer. The latter product was elaborated to afford key synthetic intermediates for polyoxin C and dysiherbaine.
研究人员在催化剂量的三氟甲磺酸三甲基硅酯存在下,研究了 2-三甲基硅氧基呋喃与 L-古洛糖衍生的手性腈的立体选择性乙烯基曼尼希反应。腈酮的 C-取代基的体积对选择性有很大影响:例如,C-苄氧基甲基腈酮可生成四种立体异构体,而体积较大的 C-[(4S)-2,2-二甲基-1,3-二氧戊环-4-基]腈酮只能生成一种立体异构体。对后一种产品进行了详细加工,以获得聚氧乙烯醚 C 和地西海因的关键合成中间体。