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Dipolar Cycloaddition Reactions with Heterocyclic Bicyclo[2.2.0]hexenes. – A Contribution to the syn – anti Selectivity of cis ‐3,4‐Disubstituted Cyclobutenes
Author(s) -
Hassenrück Karin,
Höchstetter Hans,
Martin HansDieter,
Steigel Alois,
Wingen HeinzPeter
Publication year - 1987
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.19871200212
Subject(s) - chemistry , bicyclic molecule , cycloaddition , regioselectivity , selectivity , yield (engineering) , methylene , stereochemistry , medicinal chemistry , 1,3 dipolar cycloaddition , organic chemistry , catalysis , materials science , metallurgy
In order to examine the possible preference for anti or syn attack in bicyclic cyclobutenes, a series of heterocyclic bicyclo[2.2.0]hexenes, 3 – 8 , has been subjected to the reaction towards 1,3‐dipoles, particularly diazoalkanes. All dipolar cycloadditions exclusively lead to anti ‐configurated tricyclic products with varying regiochemistry in the cases of 4 – 8 . Similarly, the Pd‐catalyzed methylene transfer reactions only yield anti products. These results are in remarkable contrast to the known cycloaddition of, e.g., dichlorocyclobutene ( 1 ) or the carbonate 24 .