New Lewis-Basic N-Oxides as Chiral Organocatalysts in Asymmetric Allylation of Aldehydes
摘要:
Allylation of aromatic and heteroaromatic aldehydes 1a-k with allyltrichlorosilane 2 can be catalyzed by the new heterobidentate, terpene-derived bipyridine N-monoxides 4, 6a,b, and 8-11 (less than or equal to 10 mol %) to afford (S)-(-)-3 with high enantioselectivities (less than or equal to99% ee). The stereochemical outcome has been found to be controlled by the axial chirality of the catalyst, which in turn is determined by the central chirality of the annulated terpene units. Solvent effects on the conversion and the level of asymmetric induction have been elucidated, and MeCN has been identified as the optimal solvent for these catalysts.
Chiral 2,2‘-Bipyridine-Type <i>N</i>-Monoxides as Organocatalysts in the Enantioselective Allylation of Aldehydes with Allyltrichlorosilane
作者:Andrei V. Malkov、Monica Orsini、Daniele Pernazza、Ken W. Muir、Vratislav Langer、Premji Meghani、Pavel Kočovský
DOI:10.1021/ol025654m
日期:2002.3.1
[reaction: see text] The Sakurai-Hosomi-type allylation of aromatic and heteroaromatic aldehydes can be catalyzed by the new heterobidenate bipyridine monoxide PINDOX with high enantioselectivities. The sterochemical outcome is mainly controlled by the axial chirality in PINDOX, which in turn is determined by the annulated terpene units.
New Lewis-Basic <i>N</i>-Oxides as Chiral Organocatalysts in Asymmetric Allylation of Aldehydes
作者:Andrei V. Malkov、Mark Bell、Monica Orsini、Daniele Pernazza、Antonio Massa、Pavel Herrmann、Premji Meghani、Pavel Kočovský
DOI:10.1021/jo035074i
日期:2003.12.1
Allylation of aromatic and heteroaromatic aldehydes 1a-k with allyltrichlorosilane 2 can be catalyzed by the new heterobidentate, terpene-derived bipyridine N-monoxides 4, 6a,b, and 8-11 (less than or equal to 10 mol %) to afford (S)-(-)-3 with high enantioselectivities (less than or equal to99% ee). The stereochemical outcome has been found to be controlled by the axial chirality of the catalyst, which in turn is determined by the central chirality of the annulated terpene units. Solvent effects on the conversion and the level of asymmetric induction have been elucidated, and MeCN has been identified as the optimal solvent for these catalysts.