Switching on and off metalation sites in triarylphosphines by manipulating substrate coordination
The inductive electron-withdrawing effect of the pos. charged P atom in triarylphosphine-BH3 adducts is largely compensated by the steric congestion caused in its vicinity. Therefore, Ph3P.BH3 reacts only sluggishly even with superbasic reagents, and products derived from ortho-metalated intermediates by their trapping with electrophiles are formed only in poor yield. However, the BH3 adducts of 3-MeOC6H4PPh2 and 3-FC6H4PPh2 are readily deprotonated at the hetero-adjacent para position and converted into final products in high yields. The P-remote regioselectivity of these phosphine-BH3 zwitterions is complementary to that previously obsd. with the corresponding phosphine oxides. [on SciFinder (R)]
Keywords: Regiochemistry (of reactions of phosphine-borane zwitterions); Lithiation; Metalation (substitution of arylphosphines via lithiation of borane adducts); Phosphines Role: RCT (Reactant) ; SPN (Synthetic preparation) ; PREP (Preparation) ; RACT (Reactant or ; arylphosphine borane adduct prepn metalation; phosphine aryl borane adduct prepn metalation; halogenation arylphosphine
Organometallic and Organometalloidal Compounds
Institut Chimie Organique,Universite Lausanne,Lausanne,Switz.
written in English.
2049-55-0; 13145-84-1 ((3-Methoxyphenyl)diphenylphosphine); 16940-66-2 (Sodium borohydride); 21388-29-4 ((3-Fluorophenyl)diphenylphosphine) Role: RCT (Reactant), RACT (Reactant or reagent) (substitution of arylphosphines via lithiation of borane adducts); 134435-28-2P; 210104-89-5P; 210104-90-8P; 210104-91-9P; 210104-92-0P; 210104-93-1P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (substitution of arylphosphines via lithiation of borane adducts); 106865-17-2P; 134435-29-3P; 210104-94-2P Role: SPN (Synthetic preparation), PREP (Preparation) (substitution of arylphosphines via lithiation of borane adducts)
Record created on 2006-03-03, modified on 2016-08-08