DBU-Catalyzed Ring Expansion or Ene-amine Formation Involving δ-Acetoxy Allenoates and N-Sulfonyl Hydrazides

DBU-catalyzed spiro-annulation and concomitant ring expansion/dominoreaction of delta-acetoxy allenoates with cycl-2-ene-N-sulfonyl hydrazides afford ring-expanded (5 -> 6, 6 -> 7, and 7 -> 8) products. By contrast, cycl-3-ene/ane-N-sulfonyl hydrazones under similar conditions deliver pyraz...

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Bibliographic Details
Published in:Organic letters Vol. 25; no. 20; pp. 3713 - 3717
Main Authors: Khan, Shabbir Ahmed, Kumar, A. Sanjeeva, Swamy, K. C. Kumara
Format: Journal Article
Language:English
Published: WASHINGTON Amer Chemical Soc 26.05.2023
Subjects:
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
KETONES
PHOSPHINE CATALYSIS
ANNULATION
IMINES
CYCLOADDITIONS
CONSTRUCTION
TOSYLHYDRAZONES
REACTIVITY
ALLENES
CYCLIZATION
ISSN:1523-7060, 1523-7052, 1523-7052
Online Access:Get more information
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Summary:DBU-catalyzed spiro-annulation and concomitant ring expansion/dominoreaction of delta-acetoxy allenoates with cycl-2-ene-N-sulfonyl hydrazides afford ring-expanded (5 -> 6, 6 -> 7, and 7 -> 8) products. By contrast, cycl-3-ene/ane-N-sulfonyl hydrazones under similar conditions deliver pyrazolecores with the same allenoate that involves allylic elimination inwhich delta-acetoxy allenoate serves as 3C-synthon. The key spirocyclicintermediates, as well as dienyl-amine intermediates, are isolatedand characterized. An extension to (R)-(-)-carvone-derivedsulfonyl hydrazide also led to ring expansion and gave pyrazoloazepine.
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ISSN:1523-7060
1523-7052
1523-7052
DOI:10.1021/acs.orglett.3c01166