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Cycloaddition of Carbodiimides with a Heteroaromatic Substituent to Allenic Acids
Author(s) -
Trifonov Latchezar S.,
Christova Nadja I.,
Dimitrov Valentin S.,
Orahovats Alexander S.
Publication year - 1992
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19920750426
Subject(s) - chemistry , substituent , pyrimidinones , cycloaddition , adduct , medicinal chemistry , stereochemistry , organic chemistry , catalysis
Cycloaddition of the allenic acid 3 with the N ‐cyclohexyl‐ N ′ ‐heteroaromatic carbodiimides 2a and 2b gave the isomeric pyrido[1,2‐ a ]pyrimidinones 4 and 5 and thiazolo[3,2‐ a ]pyrimidinones 6 and 7 , respectively, instead of the expected Diels ‐ Alder adducts analogous to 1 . The compounds of the latter type, i.e. 8 and 9 , were formed from 3 and carbodiimides 2c and 2d , respectively, containing an N ′‐(pyrazin‐2‐yl) or N ′‐(pyrimidin‐2‐yl) substituent.