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)]


Published in:
Synthesis, 7, 983-985
Year:
1998
Keywords:
Note:
CAN 129:109144
29-7
Organometallic and Organometalloidal Compounds
Institut Chimie Organique,Universite Lausanne,Lausanne,Switz.
Journal
0039-7881
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)
Laboratories:




 Record created 2006-03-03, last modified 2018-01-27


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