Three-Component Coupling Reactions of Silylglyoxylates, Alkynes, and
Aldehydes: A Chemoselective One-Step Glycolate Aldol Construction
David A. Nicewicz
Jeffrey S. Johnson
10.1021/ja043884l.s002
https://acs.figshare.com/articles/journal_contribution/Three_Component_Coupling_Reactions_of_Silylglyoxylates_Alkynes_and_Aldehydes_A_Chemoselective_One_Step_Glycolate_Aldol_Construction/3288052
A single-pot three-component coupling reaction of silylglyoxylates (<b>1</b>), terminal alkynes, and aldehydes in the presence of ZnI<sub>2</sub> and Et<sub>3</sub>N is presented. The products of the reaction, densely functionalized silyl-protected glycolate aldols (<b>2</b>), can be converted to the corresponding acetonides (<b>3</b>) in a one-pot deprotection/ketalization sequence. A variety of terminal alkynes and aldehydes can be successfully employed to give a range of highly functionalized, fully protected 1,2-diols in good yields and moderate diastereoselectivities. Mechanistic experiments suggest that the zinc acetylide reacts with the silylgyloxylate (<b>1</b>) in a chemoselective manner. Using an unoptimized (+)-<i>N</i>-methylephedrine and Zn(OTf)<sub>2</sub> system, silyl-deprotected adduct <b>2</b> was formed in 64% ee and 89:11 dr.
2005-05-04 00:00:00
diol
adduct
diastereoselectivitie
presence
ee
silylgyloxylate
terminal alkynes
Aldehyde
variety
functionalized
zinc acetylide
chemoselective manner
Construction
aldehyde
methylephedrine
unoptimized
acetonide
Chemoselective
deprotection
glycolate
sequence
yield
Alkyne
Silylglyoxylate
Aldol
dr
ZnI 2
Et 3 N
Mechanistic experiments
Glycolate
silylglyoxylate
aldol