Highly stereoselective addition of Grignard reagents to chiral open-chain α,-ketoacetals (,) has been attained. Application of the reaction to syntheses of the key intermediates (,) for (R)- and (S)-mevalolactone is also described.
Transacetalization of Diethyl Tartrate with Acetals of .alpha.-Dicarbonyl Compounds: A Simple Access to a New Class of C2-Symmetric Auxiliaries and Ligands
作者:Ulrich Berens、Dieter Leckel、Susanne C. Oepen
DOI:10.1021/jo00130a019
日期:1995.12
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.
The reactions of .alpha.-arylsulfonoxy ketones with nucleophiles
作者:Robert V. Hoffman、Bryan C. Jankowski、C. Sean Carr、Eileen N. Duesler
DOI:10.1021/jo00352a002
日期:1986.1
Synthesis and stereochemistry of 2,5-dimethoxy 3,6-disubstituted 1,4-dioxanes obtained from .alpha.-hydroxy dimethyl acetals
作者:Robert M. Moriarty、Kwang Chung Hou
DOI:10.1021/jo00198a002
日期:1984.11
MORIARTY, R. M.;HOU, KWANG-CHUNG, TETRAHEDRON LETT., 1984, 25, N 7, 691-694