[2+2] versus [4+2] cycloaddition reactions of 1,3-diaza-1,3-butadienes with various mono- and disubstituted ketenes and supporting mechanistic considerations

Sucharita Mukherjee, Sujit N. Mazumdar, Arun Sharma, Mohinder P. Mahajan

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Reactions of 1,3-diaza-1,3-butadienes with various mono- and disubstituted ketenes alongwith the associated interesting mechanistic features involved are reported. Reactions of 1,3-diazabutadienes with monosubstituted ketenes e.g. cyano-, p-nitrophenyl-, succinimido-, phthalimido- and phenoxyketenes gave [4+2] cycloadducts irrespective of the nature of azadiene and/or ketene substituents. However, diphenylketene underwent [2+2] cycloaddition reactions with 1,3-diazabutadienes (la) and gave [4+2] adducts with 1b, having electron donating function at 2-position. Interestingly, the reactions of 4-(N-arylamino)-1,3-diaza-1,3-butadienes (19) with diphenylketene gave simple nucleophilic addition products (22), whereas, their reaction with dimethylketene, yielded [4+2] cycloadducts (23). The factors influencing [2+2] versus [4+2] and cyclic versus acyclic products are also discussed.

Original languageEnglish (US)
Pages (from-to)933-950
Number of pages18
JournalHeterocycles
Volume47
Issue number2
StatePublished - Dec 1 1998

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Cycloaddition
Cycloaddition Reaction
Electrons
1,3-butadiene
ketene

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Pharmacology
  • Organic Chemistry

Cite this

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title = "[2+2] versus [4+2] cycloaddition reactions of 1,3-diaza-1,3-butadienes with various mono- and disubstituted ketenes and supporting mechanistic considerations",
abstract = "Reactions of 1,3-diaza-1,3-butadienes with various mono- and disubstituted ketenes alongwith the associated interesting mechanistic features involved are reported. Reactions of 1,3-diazabutadienes with monosubstituted ketenes e.g. cyano-, p-nitrophenyl-, succinimido-, phthalimido- and phenoxyketenes gave [4+2] cycloadducts irrespective of the nature of azadiene and/or ketene substituents. However, diphenylketene underwent [2+2] cycloaddition reactions with 1,3-diazabutadienes (la) and gave [4+2] adducts with 1b, having electron donating function at 2-position. Interestingly, the reactions of 4-(N-arylamino)-1,3-diaza-1,3-butadienes (19) with diphenylketene gave simple nucleophilic addition products (22), whereas, their reaction with dimethylketene, yielded [4+2] cycloadducts (23). The factors influencing [2+2] versus [4+2] and cyclic versus acyclic products are also discussed.",
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[2+2] versus [4+2] cycloaddition reactions of 1,3-diaza-1,3-butadienes with various mono- and disubstituted ketenes and supporting mechanistic considerations. / Mukherjee, Sucharita; Mazumdar, Sujit N.; Sharma, Arun; Mahajan, Mohinder P.

In: Heterocycles, Vol. 47, No. 2, 01.12.1998, p. 933-950.

Research output: Contribution to journalArticle

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