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Steric Effects on Reaction Rates. Part VIII. The Significance of Front Strain Release in Solvolysis of Bridgehead Derivatives
Author(s) -
Müller Paul,
Blanc Jacky,
Mareda Jiri
Publication year - 1986
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19860690314
Subject(s) - solvolysis , chemistry , steric effects , derivative (finance) , leaving group , strain (injury) , ring strain , sn2 reaction , stereochemistry , medicinal chemistry , chloride , computational chemistry , organic chemistry , molecule , catalysis , hydrolysis , medicine , financial economics , economics
The steric requirements of leaving groups for 14 bridgehead derivatives have been examined using MM2 calculations. The strain varies almost monotonously throughout the series upon variation of the leaving group from H to C1, OH, CH 3 , CH 3 CH 2 O, (CH 3 ) 3 CO, (CH 3 ) 3 C and no significant trends for differential F‐strain effects are detected expect for the perhydrophenalene derivative 13 . The experimental rates of solvolysis of bridgehead derivatives correlate well with the calculated steric energy differences between substrate R‐X and the corresponding carbenium ion R⊕. However, the strain calculations using the more recent force‐fields ( MM2 ) disagree, in part, with those reported in the literature: chloride and p ‐toluenesulfonate leaving groups correlate with identical slopes, and the perhydrotriquinacene derivative 10 shows no anomalous behavior. The calculations suggest that F‐strain and C,C‐hyperconjugation should not play any dominant role in bridgehead solvolysis.