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Highly Functionalized Vinylcyclopropane Derivatives by Regioselective and Stereoselective Reactions of Fischer Carbene Complexes with 1,4–Disubstituted Electron–Deficient 1,3–Dienes
Author(s) -
Buchert Matthias,
Reißig Hans–Ulrich
Publication year - 1992
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.19921251218
Subject(s) - chemistry , regioselectivity , carbene , cycloaddition , stereoselectivity , diene , moiety , diastereomer , nitrile , medicinal chemistry , adduct , amide , double bond , yield (engineering) , stereochemistry , organic chemistry , catalysis , metallurgy , natural rubber , materials science
The thermal reaction of Fischer carbene complex 1 with electron–deficient 1,3–dienes such as methyl ( E,E )‐2,4–hexadienoate ( 2 ) provided functionalized vinylcyclopropanes like 3 in good yields. Similar results were obtained by employing related unsaturated esters 4, 17 , and 21 or nitrile 6 . The periselectivity as well as regioselectivity of these carbene–transfer reactions are generally very high, and the diastereomer with the methoxy group cis ‐positioned with respect to the olefinic moiety is largely favoured (>85:15). A mechanistic rationale of these observations is given. Double adducts were only formed as minor sideproducts in these reactions, but by employing amide 13 as electron–deficient diene they were very easily formed with 1 . The [2 + 1] cycloaddition could also be extended to methylcarbene complex 24 and diene 2 , but the corresponding vinylcyclopropane 25a was so far only obtained in low yield.