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Iron‐Catalyzed Coupling of Tricyclo[4.1.0.0 2,7 ]hept‐1‐ylmagnesium Bromide and Related Grignard Reagents with Propargylic and Allylic Halides
Author(s) -
Hashmi A. Stephen K.,
Szeimies Günter
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270617
Subject(s) - chemistry , allylic rearrangement , medicinal chemistry , catalysis , bromide , trimethylsilyl , bicyclic molecule , propellane , coupling reaction , reagent , transmetalation , stereochemistry , organic chemistry
Abstract Several uncatalyzed and transition metal‐catalyzed cross coupling reactions of the Grignard compounds 1c or 2c with propargylic or allylic halides were investigated. Fe(acac) 3 was the most effective catalyst for the preparation of allyl‐and propargylbicyclo[1.1.0]butanes 7 and 5 . In the latter case, the formation of the isomeric allenylbicyclo[1.1.0]butanes 6 was also observed. Stereoelectronic factors of substituents like a trimethylsilyl group as a directing group could be utilized for the formation of either 5 or 6 . A number of bicyclo[1.0.0]butanes 15–21 with two substituents in the bridgehead positions were accessible by that route as well. In the case of the bis‐allenyl compound 24c , an ene‐type reaction leading to the first known derivative of a [4.1.1]propella‐2,4‐diene 25 was observed. Base‐catalyzed isomerizations of the propargylbicyclo[1.1.0]butanes 5 opened a new route to alkynylbicyclo[1.1.0]butanes 30–32 .