Abstract: The bicyclopropyl system activated by incorporation of donor and acceptor groups in the presence of Lewis acids was used as a synthetic equivalent of 1,6-zwitterions. Opening of both cyclopropane rings in 2′-aryl-1,1′-bicyclopropyl-2,2-dicarboxylates (D–A bicyclopropyl, ABCDs) in the presence of GaI3 + Bu4N+GaI4– results in 5-iodo-5-arylpent-2-enylmalonates as products of HI formal 1,6-addition to the bicyclopropyl system. The use of GaCl3 or GaBr3 as a Lewis acid and terminal aryl or alkyl acetylenes as 1,6-zwitterion interceptors allows the alkyl substituent to be grown to give the corresponding acyclic 7-chloro(bromo)-hepta-2,6-dienylmalonates. The reaction of ABCDs with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) catalyzed by Yb(OTf)3 also results in the opening of both cyclopropane rings. The reaction products are tetrahydropyridazine derivatives — (7,9-dioxo-1,6,8-triazabicyclo[4.3.0]non-3-en-2-ylmethyl)malonates — containing one more PTAD moiety in the malonyl group.

Cite: Potapov K.V. , Denisov D.A. , Glushkova V.V. , Novikov R.A. , Tomilov Y.V.
Donor–Acceptor Bicyclopropyls as 1,6-Zwitterionic Intermediates: Synthesis and Reactions with 4-Phenyl-1,2,4-triazoline-3,5-dione and Terminal Acetylenes
Journal of Organic Chemistry. 2020. V.85. N23. P.15562-15576. DOI: 10.1021/acs.joc.0c02293 WOS Scopus OpenAlex

Identifiers:

≡ Web of science:	WOS:000598137400065
≡ Scopus:	2-s2.0-85096520431
≡ OpenAlex:	W3105697585

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