Suppressed beta-effect of silicon in 3-silylated monocyclic beta-lactams: the role of antiaromaticity.
The beta-stabilizing effect of silicon substituent at C-3 on a C-4 cation and a radical in the 2-azetidinone systems is studied using NMR kinetics. While the beta-effect is virtually nonexistent in the case of a cation, a foiled beta-effect (only a 3-fold rate enhancement) is observed for a radical intermediate. From both the experimental and theoretical studies, it is demonstrated that antiaromaticity is playing the prime role in suppressing the beta-stabilizing effect of silicon.
Bag
Subhendu Sekhar
SS
Department of Chemistry, Indian Institute of Technology, Guwahati-781039, India. ssbag75@iitg.ernet.in
Kundu
Rajen
R
Basak
Amit
A
Slanina
Zdenek
Z
D001384:Azetidines / Q000737:chemistry; D015394:Molecular Structure; D008997:Monobactams / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013237:Stereoisomerism
C116379:2-azetidinone; D001384:Azetidines; D008997:Monobactams; D012825:Silicon