Mechanism of cis-enamide formation from N-(alpha-silyl)allyl amides: synthetic potential of stepwise dyotropic rearrangements.
A novel transformation of silyl amides to N-cis-propenyl amides was recently reported, the reaction of which is a formal 10-electron double sigmatropic, or dyotropic, rearrangement. Density functional calculations (B3LYP/6-311++G(3d,3p)//B3LYP/6-31G(d)) have been carried out to investigate the mechanism of this reaction. A two-step process involving sequential 1,4-silyl and 1,4-hydrogen shifts is predicted. The 1,3-dipolar azomethine ylide intermediate profits from charge stabilization by allylic resonance and phenyl conjugation. The consecutive thermal migration of two sigma-bonds (stepwise dyotropic rearrangement) is an example of a host of reactions with synthetic potential.
Zhang
Xiyun
X
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Houk
K N
KN
Lin
Songnian
S
Danishefsky
Samuel J
SJ
D000498:Allyl Compounds / Q000737:chemistry*; D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D017646:Organosilicon Compounds / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000138:chemical synthesis
D000498:Allyl Compounds; D000577:Amides; D017646:Organosilicon Compounds; D010456:Peptides, Cyclic; C408291:TMC-95A; C408292:TMC-95B