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Reaktionen von Homobenzvalenen mit 4 ‐Phenyl‐3 H ‐l,2,4‐triazol‐3,5(4 H )‐dion, Tetracyanethylen, Chlorsulfonylisocyanat und Schwefeldioxid. Einige konzertierte 1,4‐Additionen an eine Vinylcyclopropan‐Einheit
Author(s) -
Lang Reinhard,
Herzog Clemens,
Stangl Roland,
Brunn Erich,
Braun Max,
Christl Manfred,
Peters EvaMaria,
Peters Karl,
Schneringb Hans Georg Von
Publication year - 1990
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.19901230537
Subject(s) - chemistry , medicinal chemistry , adduct , tetracyanoethylene , cycloheptatriene , tetrahydrofuran , organic chemistry , solvent
Reactions of Homobenzvalenes with 4‐Phenyl‐3H‐1,2,4‐triazole‐3,5(4H)‐dione, Tetracyanoethylene. Chlorosulfonyl Isocyanate, and Sulfur Dioxide. Several Concerted 1,4‐Additions to a Vinylcyclopropane Subunit Homobenzvalene ( le ) and its derivatives 1f.g with an anellated four‐membered ring reacted with 4‐phenyl‐3 H ‐l,2,4‐tri‐ azole3,5(4 H )‐dione (PTAD) to give the pentacyclic urazole 2e and its hexacyclic derivatives 2f , g , respectively. Tetracyano‐ ethylene (TCNE) and le in benzene afforded only the Diels‐ Alder adduct 5 of norcaradiene. In other solvents the homo Diels‐Alder adduct 3a of le was formed as the main product together with some 5 and a small fraction of the cyclohexa‐ dienylcyclopropanetetracarbonitrile 4a . 5‐Methylhomobenz‐ valene ( lh ) and TCNE in acetonitrile gave 3b and 4b in the ratio 10: 1. On treatment with TCNE, dihydrohomobenzvalene ( 6 ) was converted into 8 , which is structurally related to 4 . In contrast, tetracyc10[4.1.0.0 2,4 .0 3,5 ]]heptane ( 7 ) and TCNE gave rise to the tetracyclic adduct 9 and a minor quantity of 5 . Chlorosulfonyl isocyanate reacted with le to furnish mainly the N ‐(chlorosulfony1)imino ether 10 and the N ‐(chlorosulfonyl)‐lactams 11 and 12a as well as a further isomer as byproducts. On heating, 10 rearranged to 12a . The Ksulfonyl chlorides 10 , 11 , and 12a were transformed to the N‐unsubstituted compounds 16 , 15 , and l7 , respectively, by treatment with sodium sulfite/aqueous potassium hydroxide. In wet [D6]dimethyl‐ sulfoxide 10 was converted into a cycloheptatriene derivative ( 14 ) as well as the rearranged and hydrolyzed lactam 15 , whereas 11 gave 15 exclusively. Exposure of le to sulfur dioxide yielded the 1,4 adduct 18 to the vinylcyclopropane subunit of le. Possible mechanisms of the reactions of the homobenzvalenes are discussed. In particular, the pathways to 3 , 18 , and at least to a fraction of 10 and 11 are considered to be concerted six‐electron processes. – The structures of 4a and 10 have been established by X‐ray analyses.