cyclopropanation of γ-methylidene-δ-valerolactones with aromatic aldehydes has been developed to give 4-oxaspiro[2.4]heptanes with high selectivity. The site of nucleophilic attack to a π-allylpalladium intermediate has been controlled with a sterically demanding phosphine ligand. The course of the reaction is highly dependent on ligands and solvents, and selective formation of methylenetetrahydropyrans has
                                    已经开发了
钯催化的γ-亚甲基-
δ-戊内酯与芳族醛的脱羧
环丙烷化反应,可高选择性地生成4-氧杂螺[2.4]
庚烷。对π-烯丙基铝中间体的亲核攻击位点已通过空间需求的
膦配体来控制。反应过程高度依赖于
配体和溶剂,并且已经实现了亚甲基
四氢吡喃的选择性形成。