Transacetalization of Diethyl Tartrate with Acetals of .alpha.-Dicarbonyl Compounds: A Simple Access to a New Class of C2-Symmetric Auxiliaries and Ligands
摘要:
A simple access to a new class of C-2-symmetric auxiliaries and ligands is based on the transacetalization of diethyl tartrate (1) with monoacetals of butane-2,3-dione in the key step. Acid-catalyzed reaction of 1 with 2 equiv of 3,3-diethoxybutan-2-one (2) gives the C-2-symmetric 1,4-dioxane 7 in 88% yield. Reduction of 7 with LiAlH4 affords the crystalline diol 9. The structure of 7 was established from the X-ray structure of 9. Dioxane 7 was converted by standard methodology into the diphosphine 24 and the TARTROL 22. Reaction of 1 with 3,3-dimethoxybutan-2-one (3) in the presence of BF3-etherate gives in analogy to the formation of 7 the 1,4-dioxane 8. This compound was transformed into the diphosphine 25 and the TARTROL 23. The trans-diaxial relationship of the methoxy groups present in 8 could be deduced without X-ray analysis from the H-1-NMR spectrum of 23.
Chiral <i>C</i><sub>2</sub>-Symmetric Ligands with 1,4-Dioxane Backbone Derived from Tartrates: Syntheses and Applications in Asymmetric Hydrogenation
作者:Wenge Li、Jason P. Waldkirch、Xumu Zhang
DOI:10.1021/jo020250t
日期:2002.11.1
Chiral 1,4-diphenylphosphines 5-7 as well as thioether 8 were synthesized from tartrates employing Ley's "BDA" and "Dispoke" methodologies as the key step. Rhodium(I) complexes with 5-7 are efficient catalysts for the asymmetrichydrogenation of beta-substituted enamides and MOM-protected beta-hydroxyl enamides, which furnished chiral amines or beta-amino alcohols with 94-->99% ee. These results indicated
Method for the production of amines by reductive amination of carbonyl compounds under transfer-hydrogenation conditions
申请人:——
公开号:US20040267051A1
公开(公告)日:2004-12-30
The invention relates to the production of amines by the reaction of aldehydes or ketones with ammonia or primary or secondary amines in the presence of a hydrogen-donor and the presence of homogeneous metal catalysts of the eighth sub-group under mild conditions.