Highly Enantio- and Regioselective Allylic Alkylations Catalyzed by Chiral [Bis(dihydrooxazole)]molybdenum Complexes
摘要:
A series of chiral C-2-symmetric bis[dihydrooxazoles] with a trans-1,2-diaminocyclohexane backbone was synthesized. In view of the promising results obtained by Trost et al with related bis[pyridine] ligands, we tested these new ligands in the enantioselective molybdenum-catalyzed allylic alkylation of 1- and 3-monosubstituted allylic substrates. Enantiomer excesses of up to 98% and branched/linear ratios of up to 11 : 1 were obtained with (E)-3-(alkyl)allyl carbonates. (E)-3-Phenoxyallyl acetate gave a branclied/linear ratio of > 20:1 and an ee of 98%. Crystal structures of the free ligand 7a and of its tricarbonylmolybdenum(0) complex 28 are reported.
Enantioselective Molybdenum-Catalyzed Allylic Alkylation Using Chiral Bisoxazoline Ligands
作者:Frank Glorius、Andreas Pfaltz
DOI:10.1021/ol990602r
日期:1999.7.1
[GRAPHICS]A series of chiral C-2-symmetric bisoxazolines with trans-1,2-diaminocyclohexane backbones was synthesized. In View of the promising results obtained by Trost with analogous bispyridine ligands, we tested our new ligands in the enantioselective molybdenum-catalyzed allylic alkylation of 1- and 3-monosubstituted allylic substrates, Enantiomeric excesses of up to 98% and branched/linear ratios of up to 11:1 were obtained with (E)-3-(n-alkyl)allyl carbonates. (E)-3-Phenoxyallyl acetate gave a branched/linear ratio of >20:1 and an ee of 98%.
Highly Enantio- and Regioselective Allylic Alkylations Catalyzed by Chiral [Bis(dihydrooxazole)]molybdenum Complexes
A series of chiral C-2-symmetric bis[dihydrooxazoles] with a trans-1,2-diaminocyclohexane backbone was synthesized. In view of the promising results obtained by Trost et al with related bis[pyridine] ligands, we tested these new ligands in the enantioselective molybdenum-catalyzed allylic alkylation of 1- and 3-monosubstituted allylic substrates. Enantiomer excesses of up to 98% and branched/linear ratios of up to 11 : 1 were obtained with (E)-3-(alkyl)allyl carbonates. (E)-3-Phenoxyallyl acetate gave a branclied/linear ratio of > 20:1 and an ee of 98%. Crystal structures of the free ligand 7a and of its tricarbonylmolybdenum(0) complex 28 are reported.