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Ring Contractions of 4‐Oxoquinolizine‐3‐diazonium Tetrafluoroborates, by an Aza Wolff Rearrangement, to Alkyl Indolizine‐3‐carboxylates
Author(s) -
Rečnik Simon,
Svete Jurij,
Stanovnik Branko
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200110)2001:19<3705::aid-ejoc3705>3.0.co;2-l
Subject(s) - indolizine , chemistry , wolff rearrangement , alkyl , alcohol , ring (chemistry) , medicinal chemistry , organic chemistry , diazo
Abstract The 1‐substituted 3‐amino‐4 H ‐quinolizin‐4‐ones 13 , available in two steps from 10 and methyl ( Z )‐2‐benzyloxycarbonylamino‐3‐(dimethylamino)propenoate ( 11 ), were diazotized to give the stable diazonium tetrafluoroborates 7a and 7b . Heating of these diazonium salts in alcohols gave mixtures of 3‐unsubstituted quinolizine derivatives 8a and 8b and the alkyl indolizine‐3‐carboxylates 9a − h . The ratio of the two types of products 8 and 9 was dependent on the type of alcohol employed. Thus, treatment of 7a or 7b with 2‐propanol predominantly resulted in the 3‐unsubstituted quinolizinones 8 , while treatment of 7a or 7b with primary alcohols gave the indolizine‐3‐carboxylates 9 as the major products in most cases. The transformation of the 4‐oxoquinolizine‐3‐diazonium tetrafluoroborates 7a and 7b into the alkyl indolizine‐3‐carboxylates 9a − h represents the first example of a Wolff rearrangement in the fused cyclic α‐diazoamide series.