Journal
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume 130, Issue 30, Pages 9942-9951Publisher
AMER CHEMICAL SOC
DOI: 10.1021/ja802935w
Keywords
-
Categories
Funding
- NIGMS NIH HHS [GM-57212] Funding Source: Medline
Ask authors/readers for more resources
Alkylations of pyridyl-substituted ynones with Et(2)Zn and Me(2)Zn, promoted by amino acid-based chiral ligands in the presence of Al-based alkoxides, afford tertiary propargyl alcohols efficiently in 57% to >98% ee. Two easily accessible chiral ligands are identified as optimal for reactions of the two dialkylzinc reagents. Catalytic alkylations with Et(2)Zn require a chiral ligand carrying two amino acid moieties (valine and phenylalanine) along with a p-trifluoromethylphenylamide C-terminus. In contrast, reactions with Me(2)Zn are most effectively promoted in the presence of a chiral ligand containing a single amino acid (benzyl cysteine), capped by an n-butylamide. Enantiomerically enriched tertiary alcohols bearing a pyridyl and an alkyne substituent can be functionalized in a variety of manners to furnish a wide range of difficult-to-access acyclic and heterocyclic structures; two noteworthy examples are Cu-catalyzed protocols for conversion of tertiary propargyl alcohols to enantiomerically enriched tetrasubstituted allenes and bicyclic amides that bear an N-substituted quaternary carbon stereogenic center. Mechanistic models that account for the trends and enantioselectivity levels are provided.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available