Synthesis of Fluorinated β‑Aminophosphonates and γ‑Lactams
2016-02-19T11:22:51Z (GMT) by
The functionalized polyfluorophosphorylated 1-azadienes <b>I</b> have been prepared by a Wittig reaction of ethyl glyoxalate and perfluorophosphorylated conjugated phosphoranes, obtained by reaction of phosphazenes and fluorinated acetylenic phosphonates. Subsequent reduction of both carbon–carbon and carbon–nitrogen double bonds of these 1-azadienes <b>I</b> affords the fluorine-containing β-aminophosphonates <b>II</b>, with the <i>syn</i> β-aminophosphonate being obtained as the major diastereoisomer. Base-mediated cyclocondensation of a diastereomeric mixture of aminophosphonates <b>II</b> leads exclusively to a new type of functionalized <i>trans</i>-γ-lactams <b>III</b> in a diastereoselective way. A computational study has also been used to explain the observed diastereoselectivity of these reactions.