Fluoride-Mediated Dephosphonylation of α‑Diazo-β-carbonyl Phosphonates

The
possibility of fluoride-mediated selective dephosphonylation
of α-diazo-β-carbonyl phosphonates such as the Ohira–Bestmann
reagent has been proposed and executed. The resulting α-diazocarbonyl
intermediates undergo a (3 + 2)-cycloaddition at room temperature
with conjugated olefins and benzynes. Interestingly, under the current
conditions, the resulting cycloaddition products underwent either N-acylation (with excess α-diazo-β-carbonyl
phosphonates) or Michael addition (with conjugated olefins).

针对α-重氮-β-羰基膦酸酯类化合物（如大井-贝斯特曼试剂（Ohira–Bestmann reagent））的氟介导选择性脱膦酰化反应，其可行性已被提出并成功实现。所得α-重氮羰基中间体可在室温下与共轭烯烃及苯炔发生(3+2)环加成反应。值得注意的是，在当前反应条件下，所得环加成产物会发生两类不同的后续反应：当体系中存在过量α-重氮-β-羰基膦酸酯时发生N-酰化反应，而与共轭烯烃共存时则发生迈克尔加成反应。