A Useful Zinc Reagent for the Preparation of 2-Oxo-1,1-Difluoroalkylphosphonates

Abstract

The treatment of dialkyl bromodifluoromethylphosphonates with activated zinc dust in various solvents gave dialkoxyphosphinyldifluoromethy1zinc compounds 2, which were acylated with acid halides or fluorinated acid anhydride to afford dialkyl 2-oxo-1,1-difluoroalkylphosphonates in good yields.

Methods for the Synthesis of α,α‐Difluoroketones

“…However, organometallic reagents derived from difluorophosphonates have been found to have reasonable to good stability and have been quite widely utilized (Scheme 17). Both lithium-and zinc-difluorophosphonate reagents have been reported, formed either by the reaction of (EtO) 2 OPCF 2 Br with zinc metal, [46] or (EtO) 2 OPCF 2 H with LDA. [47] The zinc reagents are particularly stable, forming a colourless, clear solution which can be stored for several months at room temperature and can survive heating up to 100°C for short periods.…”

Synthesis of 3‐Trifluoro‐2‐hydroxy/amino‐1‐fluoropropylphosphonates†

“…The resultant 1 thus obtained was transferred to corresponding reactive organic zinc reagent 2 in reaction with activated zinc powder. 5,6 Thermorearrangement of 2 with N-(-)-α′-methylbenzyl acetiminodoyl chloride, which was prepared conveniently by a one-pot procedure, 7 gave the key intermediate 3 (Scheme 1). As observed by us, the basicity of the reagent controlled such [1,3]-proton shift process in this reaction system.…”

Fluorinated Organozinc Reagents

“…A variety of solvents can be employed. The thermal stability of these zinc reagents parallel their fluorinated vinyl and alkynyl counterparts 148 . For example, only 49% of (BuO) 2 P(O)CF 2 ZnX decomposed on heating to 100 • C for 4 hours and homogeneous solutions of the zinc reagents can be stored at room temperature for months without change.…”

“…Treatment of dialkyl bromodifluoromethylphosphonates with zinc gives the dialkoxyphosphinyldifluoromethylzinc reagents in good yields (equation 109) 148 . A variety of solvents can be employed.…”