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Enantioselective carbonylation reactions of para ‐substituted 2‐phenylpropenes
Author(s) -
Consiglio Giambattista,
Roncetti Lucia
Publication year - 1991
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.530030420
Subject(s) - chemistry , regioselectivity , enantioselective synthesis , carbonylation , catalysis , hydroformylation , stereochemistry , medicinal chemistry , structural isomer , organic chemistry , rhodium , carbon monoxide
The enantioselective hydroformylation catalyzed by [(R,R)‐Diop]Pt(SnCl 3 )Cl7 and the enantioselective hydroisopropoxycarbonylation catalyzed by [(R,R)‐Diop]PdCl 2 8 or by [(R,R)‐Diop‐dbp]PdCl 2 9 of some para ‐substituted 2‐phenylpropenes ( para substituents = NO 2 , H, CH 3 O, Cl, CF 3 ) was investigated in order to recognize possible electronic influences on the regioselectivity and on the enantioface selection which take place in such carbonylation reactions. The catalytic systems used gave no carbonylation products when the nitro compound was the substrate. 7 and 8 show similar regioselectivities, the less branched isomer being exclusively formed for all substrates except p ‐methoxy‐2‐phenylpropene which gave small amounts of the alternative regioisomer. The enantioselectivity depends on the σ p effect of the substituent in both cases; the differences are, however, rather small and the trend is opposite in the two cases. The regioselectivity displayed by 9 is still in favour of the less branched isomer but it is high only in the case of p ‐trifluoromethyl‐2‐phenylpropene. Larger differences with respect to the other catalytic systems were also observed for enantioselectivity but the trend for both regioselectivity and enantioselectivity is not linear.