Alcaide Benito, Almendros Pedro, Aragoncillo Cristina
Departamento de Química Orgánica I Facultad de Química Universidad Complutense de Madrid, 28040 Madrid, Spain.
Chemistry. 2002 Apr 2;8(7):1719-29. doi: 10.1002/1521-3765(20020402)8:7<1719::aid-chem1719>3.0.co;2-u.
Metal-mediated carbonyl allenylation and propargylation of 4-oxoazetidine-2-carbaldehydes were investigated in aqueous environment. Different propargyl bromide and metal promoters showed varied regio- and stereoselectivities on product formation. In addition, an unprecedented one-pot stereoselective synthesis of beta-chlorinated allylic alcohols, which can also be considered as functionalized allylsilanes, has been developed, which involves tin(IV) chloride-mediated reaction of propargyltrimethylsilane and 4-oxoazetidine-2-carbaldehydes. Some of the resulting coupling products were submitted to transition metal catalyzed reactions, such as the allenic Pauson-Khand and palladium-catalyzed reactions, leading to novel fused or bridged tricyclic beta-lactams. Remarkably, a novel domino process, namely the allene cyclization/intramolecular Heck reaction was found. A likely mechanism for the cascade reaction should involve an intramolecular cyclization on a (pi-allyl)palladium complex and a Heck-type reaction.
在水性环境中研究了金属介导的4-氧代氮杂环丁烷-2-甲醛的羰基烯丙基化反应和炔丙基化反应。不同的炔丙基溴和金属促进剂在产物形成上表现出不同的区域选择性和立体选择性。此外，还开发了一种前所未有的一锅法立体选择性合成β-氯化烯丙醇的方法，该方法也可视为官能化烯丙基硅烷，涉及四氯化锡介导的炔丙基三甲基硅烷与4-氧代氮杂环丁烷-2-甲醛的反应。一些所得的偶联产物进行了过渡金属催化的反应，如烯丙基型Pauson-Khand反应和钯催化反应，生成了新型稠合或桥连的三环β-内酰胺。值得注意的是，发现了一种新型多米诺过程，即丙二烯环化/分子内Heck反应。该串联反应的可能机理应涉及在（π-烯丙基）钯配合物上的分子内环化反应和Heck型反应。
