1,3-dipolar cycloaddition of 2-dialkylaminothioisomünchnones with aliphatic aldehydes: synthesis of beta-lactams and thiiranes, structure elucidation, and rationale for chemoselective fragmentation of cycloadducts.
J Org Chem
; 68(16): 6338-48, 2003 Aug 08.
Article
in En
| MEDLINE
| ID: mdl-12895069
ABSTRACT
A series of highly funtionalized beta-lactams and thiiranes can be generated on treatment of 1,3-thiazolium-4-olates (thioisomünchnones) with aliphatic aldehydes. Although in some cases a variety of products have been obtained, the present paper now provides a mechanistic rationale to explain the product distribution based on stereoelectronic effects. Thus, ring fragmentation of the initial [3+2] cycloadduct is essentially dictated by the electronic character of the aryl substituent on the nitrogen atom of the parent thioisomünchnone. However, further evolution of such cycloadducts into beta-lactams or thiiranes is governed by steric effects to a large extent. Evidence for such interactions has been obtained by computing PM3-optimized diastereomeric transition structures in the reaction of a thioisomünchnone with a chiral aliphatic aldehyde.
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Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Org Chem
Year:
2003
Document type:
Article
Affiliation country:
Spain