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Stereoselectivity in a series of 7‐alkylbicyclo[3.2.0]hept‐2‐enes: Experimental and computational perspectives
Author(s) -
Leber Phyllis,
Kidder Katherine,
Viray Don,
DietrichPeterson Eric,
Fang Yuan,
Davis Alexander
Publication year - 2018
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3888
Subject(s) - chemistry , sigmatropic reaction , stereoselectivity , isopropyl , alkyl , reaction rate constant , fragmentation (computing) , computational chemistry , stereochemistry , medicinal chemistry , organic chemistry , kinetics , physics , quantum mechanics , computer science , operating system , catalysis
Rate constants for overall decomposition ( k d ) for a series of exo ‐7‐alkylbicyclo[3.2.0]hept‐2‐enes are relatively invariant. For the alkyl substituents ethyl, propyl, butyl, isopropyl, and t ‐butyl, the ratio of the rate constant for [1,3] sigmatropic rearrangement to the rate constant for fragmentation, k 13 / k f , is significantly lower than k 13 / k f = 150 observed for exo ‐7‐methylbicyclo[3.2.0]hept‐2‐ene. Regardless of the size and mass of the alkyl group, the stereoselectivity of the [1,3] carbon migration appears to be quite stable at 80% to 89% suprafacial inversion ( si ), an observation consistent with conservation of angular momentum but not conservation of orbital symmetry. This global result comports with the phenomenon of “dynamic matching” espoused by Carpenter and collaborators for [1,3] sigmatropic rearrangements in general.