Contrasting Carboannulation Involving δ‑Acetoxy Allenoate as a Four-Carbon Synthon Using DABCO and DMAP: Access to Spiro-carbocyclic and m‑Teraryl Scaffolds

Spiro-annulation involving δ-acetoxy allenoate and alkyl benzoisothiazole dioxide (N-sulfonyl ketimine) triggered by DABCO/MeCO2H combination leads to an essentially single diastereomer via chemo- and regiospecific [4 + 2]-carboannulation and a new hydroxyl group is introduced. In contrast, DMAP-cat...

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Bibliographic Details
Published inOrganic letters Vol. 23; no. 3; pp. 1123 - 1129
Main Authors Kumar, A. Sanjeeva, Chauhan, Sachin, Swamy, K. C. Kumara
Format Journal Article
LanguageEnglish
Published WASHINGTON American Chemical Society 05.02.2021
Amer Chemical Soc
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
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Summary:Spiro-annulation involving δ-acetoxy allenoate and alkyl benzoisothiazole dioxide (N-sulfonyl ketimine) triggered by DABCO/MeCO2H combination leads to an essentially single diastereomer via chemo- and regiospecific [4 + 2]-carboannulation and a new hydroxyl group is introduced. In contrast, DMAP-catalyzed benzannulation using the same reactants affords unsymmetrical m-teraryls via Mannich coupling, sequential proton transfers, and C–N bond cleavage. Here, δ-acetoxy allenoate serves as a 4C-synthon and the carboannulation is completely base dependent and mutually exclusive.
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ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.1c00076