Chemistry of four-membered cyclic nitrones. 2. 1,3-Dipolar cycloaddition reactions with electron-deficient acetylenes and conversion of the 1,3-dipolar adducts into pyridine derivatives
作者:Marcel L. M. Pennings、Guerol Okay、David N. Reinhoudt、Sybolt Harkema、Gerrit J. Van Hummel
DOI:10.1021/jo00144a005
日期:1982.11
Chemistry of four-membered cyclic nitrones. 1. Synthesis and thermal isomerization of 2,3-dihydroazete 1-oxides
作者:Marcel L. M. Pennings、David N. Reinhoudt
DOI:10.1021/jo00349a004
日期:1982.5
Extension of the Woodward-Hoffmann rules to heterocyclic systems: stereospecific thermal isomerization of 1-azacyclobutene 1-oxides
作者:M. L. M. Pennings、D. N. Reinhoudt、S. Harkema、G. J. Van Hummel
DOI:10.1021/ja00545a033
日期:1980.12
tography of the mixture on silica gel allowed the isolation of Sa in 60% yield, based on unrecovered starting material. In order to form the tetrahydro and dihydrofuran rings in phytuberin, diol 5b, which was prepared by hydrogenolysis of the benzyl groups in 5a, was reacted with 3.5 equiv of DIBAL-H (-40 'C, 1.0 h; 0 'C, 0.5 H), as described for the reduction of the related formylspirob~tenolide.~
基于未回收的起始材料,在硅胶上对混合物进行色谱分析允许以 60% 的产率分离 Sa。为了在 phytuberin 中形成四氢和二氢呋喃环,将通过 5a 中的苄基氢解制备的二醇 5b 与 3.5 当量的 DIBAL-H(-40 ℃,1.0 小时;0 ℃,0.5 H),如对相关甲酰螺内酯的还原所述。~ 用 2 N NaOH 处理混合物得到脱乙酰植物块茎素 (lb),[ a I 2 f D -34.6' (c 0.1, EtOH),产率为 63% . 这种材料表现出与先前报道的那些相同的光谱特性。~ ~lb (Ac20, Et3N, 催化量的 4-NJV-二甲基氨基吡啶'~) 的乙酰化得到 71% (-)-phytuberin (la), [(u]24D -34.0' (c 0.25, EtOH)