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ZnBr 2 /CuCN‐Promoted, Highly Regioselective S N 2′ Reactions of Some Functionalised Organolithium Compounds with Allylic and Propargylic Halides
Author(s) -
Yus Miguel,
Gomis Joaquín
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300094
Subject(s) - chemistry , regioselectivity , allylic rearrangement , lithium (medication) , methoxide , medicinal chemistry , bromide , catalysis , hydrolysis , halide , copper , cyanide , organic chemistry , zinc bromide , zinc , medicine , endocrinology
Treatment of lithium (2‐lithiomethylphenyl)methoxide ( 2a ) and lithium 2‐(2‐lithiomethylphenyl)ethoxide ( 2b ) [easily prepared by ring opening of phthalan ( 1a ) and isochroman ( 1b ), respectively, by the use of lithium and a catalytic amount of 4,4′‐di‐ tert ‐butylbiphenyl (DTBB)] with zinc bromide and copper cyanide, both in equimolecular amounts, in THF at room temperature, followed by treatment with different allylic chlorides or bromides 3 at −78 or 20 °C, almost exclusively provides (after hydrolysis with water) the corresponding alcohols 4 ′ resulting from an S N 2′ displacement, the process being highly regioselective. The same procedure with intermediates 2a and 2b was applied to propargylic chlorides or bromides 5 , exclusively yielding the corresponding allenylic alcohols 6 ′ , resulting from an S N 2′ reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)