N-propargylamides via the asymmetric michael addition of B-alkynyl-10-TMS-9- borabicyclo[3.3.2]decanes to N-acylimines.
[Structure: see text] The asymmetric synthesis of N-propargylamides through Michael addition of the alkynylborane 1 to N-acylimines is reported. The N-acetylimines provide the best substrates for the process exhibiting high selectivity (56-95% ee) with predictable stereochemistry. In several cases, 5 crystallizes in essentially pure form (97-99% ee) and a single-crystal X-ray structure was also obtained for 5g (R1=R2=Me, R3=o-Cl-C6C4). The process regenerates 4 for its direct conversion back to 1 and facilitates the efficient recovery of the pseudoephedrine.
Gonzalez
Ana Z
AZ
University of Puerto Rico, Department of Chemistry, Rio Piedras, Puerto Rico 00931-3346.
Canales
Eda
E
Soderquist
John A
JA
D000480:Alkynes / Q000737:chemistry*; D000577:Amides / Q000138:chemical synthesis*; D001896:Boron Compounds / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004809:Ephedrine / Q000138:chemical synthesis*; D007097:Imines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism
D000480:Alkynes; D000577:Amides; D001896:Boron Compounds; D007097:Imines; D004809:Ephedrine