Temperature‐Assisted Generation of Arylmethyl Radicals from Bis(arylmethyl)tin Dichlorides: Efficient Reagents for − Bond‐Forming Reactions

Abstract

The oxidative-addition reaction between an arylmethyl chloride (RCH 2 Cl; R=1-C 10 H 7 , 2,4,6-Me 3 C 6 H 2 , 4-MeC 6 H 4 , 3-MeC 6 H 4 , C 6 H 5 , 4-ClC 6 H 4 ) and tin powder in boiling toluene produces bis(arylmethyl)tin dichlorides, [(RCH 2 ) 2 SnCl 2 ] in good yields. At 160 °C in mesitylene bis(1-naphthylmethyl)tin dichloride undergoes SnÀ C homolytic cleavage to generate two 1-naphthylmethyl radicals (1-C 10 H 7 CH 2 * ) which were trapped by TEMPO (C 9 H 8 NO * ). Subsequently, the radicals (RCH 2 * ) produced in this manner were utilized for efficient substitution reactions with electron-rich arenes (R'H; R' = 2,4,6-Me 3 C 6 H 2 , 1,2,4,5-Me 4 C 6 H, 1,2,3,4,5-Me 5 C 6 ) to obtain a variety of unsymmetrical diarylmethanes (RR'CH 2 ). The addition of one equivalent of iodine (I 2 ) to the reaction mixture resulted in a significant increase in the yields of coupled products.