Synthesis of the B-ring of FR182877. Investigation of the reactions of 6-fumaryl 1,3,8-nonatrienes
作者:Paul A. Clarke、Rebecca L. Davie、Simon Peace
DOI:10.1016/j.tet.2005.01.014
日期:2005.2
under standard Diels–Alder cyclisation conditions. This rearrangement became the exclusive pathway when the reaction was performed in the presence of a Lewis acid. As expected from modeling studies, the major intramolecular Diels–Alder cyclisation product was the desired exo-trans adduct, which was required for the synthesis of FR182877. Intrigued by the rearrangements, a number of alterations were made
据报道,分子内的Diels-Alder反应是由C5处的乙烯基取代的6-富芳基1,3,8-壬烯,以提供FR182877的B环。所需的1,3,8-壬二烯的合成可以快速,高收率地完成。在标准Diels-Alder环化条件下加热时,发现在C5处被乙烯基取代的6-Fumaryl 1,3,8-壬二烯会发生竞争性的串联σ重排/ Diels-Alder环化。当在路易斯酸的存在下进行反应时,这种重排成为排他性途径。由于模拟研究的预期,主要分子内第尔斯-阿尔德环化产物,但所需的外型-反式加合物,这是合成FR182877所必需的。重排引起了人们的兴趣,对1,3,8-壬三烯进行了许多改动。用乙酰基取代富马芳基导致1,3,8-壬三烯的反应性降低,但未观察到重排或环加成。发现C5取代基的变化对于确定Diels–Alder环化反应的π非对映选择性非常重要。