Convergent Access to Bis-spiroacetals through a Sila-Stetter–Ketalization Cascade
摘要:
An NHC-catalyzed sila-Stetter reaction between aliphatic acylsilanes and vinylketones bearing silyl ether substituents affords functionalized 1,4-diketones, which upon treatment under acidic conditions leads to the corresponding bis-spiroacetals. The two-step sequence may also be carried out in a one-pot operation leading to high yields of the desired bis-spiroacetals.
A simple and efficient method for the prepn. of β-hydroxyacylsilanes has been developed through a TiCl4-mediatedaldolreaction of acylsilanes with aldehydes. Acylsilane EtCOSiMe2Ph reacted with PhCHO giving 80:20 diastereomeric syn-anti mixt. of PhCH(OH)CHMeCOSiMe2Ph under TiCl4 catalysis. Similarly, arom. aldehydes contg. electron-withdrawing substituents, and isobutyraldehyde iPrCHO gave the hydroxyacyl
Asymmetric Synthesis of β-Amino Amides by Catalytic Enantioconvergent 2-Aza-Cope Rearrangement
作者:C. Guy Goodman、Jeffrey S. Johnson
DOI:10.1021/jacs.5b09593
日期:2015.11.25
kinetic resolutions of α-stereogenic-β-formyl amides in asymmetric 2-aza-Cope rearrangements are described. Chiral phosphoric acids catalyze this rare example of a non-hydrogenative DKR of a β-oxo acid derivative. The [3,3]-rearrangement occurs with high diastereo- and enantiocontrol, forming β-imino amides that can be deprotected to the primary β-amino amide or reduced to the corresponding diamine
Efficient Synthesis of Acylsilanes Using Morpholine Amides
作者:Christopher T. Clark、Benjamin C. Milgram、Karl A. Scheidt
DOI:10.1021/ol0483854
日期:2004.10.1
text] A general synthesis of acylsilanes from the corresponding morpholine amides and silyllithium species is described. The use of morpholine amides is economical and prevents over-addition by the silyl nucleophile. The procedure cleanly affords acylsilanes in good yields and circumvents the use of stoichiometric copper(I) cyanide typically employed to synthesize these compounds from acid chlorides.
An NHC-catalyzed sila-Stetter reaction between aliphatic acylsilanes and vinylketones bearing silyl ether substituents affords functionalized 1,4-diketones, which upon treatment under acidic conditions leads to the corresponding bis-spiroacetals. The two-step sequence may also be carried out in a one-pot operation leading to high yields of the desired bis-spiroacetals.