Bromodecarboxylation of (E)‐3‐Aryl‐2‐(diethoxyphosphoryl)acrylic Acids: A Facile Route to Diethyl Arylethynylphosphonates.

Abstract

Organo-phosphorus compounds S 0080Bromodecarboxylation of (E)-3-Aryl-2-(diethoxyphosphoryl)acrylic Acids: A Facile Route to Diethyl Arylethynylphosphonates. -Bromodecarboxylation of acids (I) using sodium bromide in the presence of Oxone provides the arylbromovinylphosphonates (II) in a highly stereoselective manner. This type of compound is useful for the synthesis of diethylarylethynylphosphonates (III). TBD-promoted bromine elimination of (IIf) results in a complex reaction mixture. In all reactions performed, only the Z-isomer undergoes β-elimination whereas the E-isomer remains unreacted. -(KRAWCZYK*, H.; ALBRECHT, L.; Synthesis 2007, 12, 1877-1881; Inst. Org. Chem., Tech. Univ., PL-90-924 Lodz, Pol.; Eng.) -H. Hoennerscheid 44-164

Decarboxylative Halogenation of Organic Compounds

“…Stoichiometric combinations of Oxone (KHSO 5 )/NaCl, NaBr or NaI in the presence of Na 2 CO 3, afforded ( E )-β-halostyrenes ( Scheme 123 a) and 2-aryl-1-bromophosphonates ( Scheme 123 b) from the corresponding ( E )-α,β-unsaturated acids. 339 , 340 While bromo- and chloroalkenes were obtained in useful yields, iododecarboxylation by this approach was less effective (yields 0–45%). The stereoselectivity varies from high to moderate, which might impose certain limitations on the method.…”