Synthesis of 3,6-dihydro-2H-pyran-2-ones via cationic palladium(II) complex-catalyzed tandem [2+2] cycloaddition-allylic rearrangement of ketene with α,β-unsaturated aldehydes and ketones
作者:Tetsutaro Hattori、Yutaka Suzuki、Yuuichi Ito、Daido Hotta、Sotaro Miyano
DOI:10.1016/s0040-4020(02)00509-4
日期:2002.6
Treatment of ketene with α,β-unsaturated aldehydes and ketones in the presence of [Pd(dppb)(PhCN)2](BF4)2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon
在[Pd(dppb)(PhCN)2 ](BF 4)2存在下,用α,β-不饱和醛和酮处理乙烯酮会导致形成4-乙烯基氧杂环丁烷-2-酮,并在以下条件下重排:取决于取代基,以各种收率得到3,6-二氢-2 H-吡喃-2-酮。通过使用在β位置带有不对称碳中心的α,β-不饱和醛,可以实现高达57%de的不对称诱导。通过对4-乙烯基氧杂环丁烷-2-酮的C(4)-O键进行异质裂解而产生的两性离子被认为是烯丙基重排的中间产物。3,6-二氢-6-甲基-2 H的乙醇分解-吡喃-2-酮在酸性条件下,然后将所得的2,4-己二烯酸乙酯(山梨酸乙酯)皂化,以90%的产率得到山梨酸。