Stereoretentive cross-coupling of boronic acids
The present disclosure provides tri-orthoalkylphenyl phosphine catalysts of formula I wherein A is CH2, C═O, or NR A ; R 1 is aryl, heteroaryl, isopropyl, tert-butyl, cycloalkyl, or heterocycloalkyl, wherein aryl, heteroaryl, cycloalkyl and heterocycloalkyl are optionally substituted; R 2 is H, (C 1 -C 8 )alkyl, (C 1 -C 8 )alkoxy, N(R A ) 2 , or an electron withdrawing group; and each R A is independently H or (C 1 -C 8 )alkyl; that are tuned electrically and sterically.
1. A phosphine compound of Formula I:
wherein
A is CH 2 , C═O, or NR A ;
R 1 is aryl, heteroaryl, tert-butyl, cycloalkyl, or heterocycloalkyl, wherein aryl, heteroaryl, cycloalkyl and heterocycloalkyl are optionally substituted;
R 2 is H, (C 1 -C 8 )alkyl, (C 1 -C 8 )alkoxy, N(R A ) 2 , or an electron withdrawing group; and
each R A is independently H or (C 1 -C 8 )alkyl; wherein the electron withdrawing group is halo, trifluoromethyl, pentafluoroethyl, trifluoromethoxy, nitrile, nitro, CO 2 R A , C(O)N(R A ) 2 , SO 2 R A , SO 2 N(R A ) 2 , or P(O)[N(R A ) 2 ] 2 .
2. The phosphine compound of claim 1 wherein R 1 is aryl or (C 3 -C 8 )cycloalkyl, wherein aryl and (C 3 -C 8 )cycloalkyl are optionally monosubstituted or disubstituted.
3. A The phosphine compound of Formula II:
wherein
R 1 is phenyl or (C 3 -C 6 )cycloalkyl, wherein phenyl and (C 3 -C 6 )cycloalkyl are optionally monosubstituted or disubstituted; and
R 2 is H, (C 1 -C 5 )alkyl, (C 1 -C 5 )alkoxy, N(R A ) 2 , halo, trifluoromethyl, pentafluoroethyl, trifluoromethoxy, nitrile, nitro, CO 2 R A , or C(O)N(R A ) 2 ; and each R A is independently H or (C 1 -C 8 )alkyl.
4. The phosphine compound of claim 3 wherein R 2 is H, halo, trifluoromethyl, pentafluoroethyl, trifluoromethoxy, nitrile, nitro, CO 2 R A , or C(O)N(R A ) 2 .
5. The phosphine compound of claim 3 wherein the phosphine compound is phosphine compound of Formula III:
6. The phosphine compound of claim 5 wherein R 2 is H, methyl ethyl, methoxy, ethoxy, dimethylamine, diethylamine, halo, trifluoromethyl, pentafluoroethyl, trifluoromethoxy, nitrile, nitro, CO 2 R A , or C(O)N(R A ) 2 .
7. The phosphine compound of claim 3 wherein the phosphine compound is one of phosphine compounds IIIA-IIIC: