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Reaction of sulfene and dichloroketene with open‐chain N,N ‐disubstituted α‐aminomethyleneketones. Synthesis of N,N ‐disubstituted 4‐amino‐3,4‐dihydro‐(5‐methyl‐6‐phenyl)(5,6‐diphenyl)‐1,2‐oxathiin 2,2‐dioxides and of 4‐amino‐3‐chloro‐5‐methyl‐6‐phenyl‐2 H ‐pyran‐2‐ones
Author(s) -
Bargagna Alberto,
Sche Pietro,
Bondavalli Francesco,
Longobardi Mario
Publication year - 1980
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570170609
Subject(s) - chemistry , cycloaddition , yield (engineering) , pyran , medicinal chemistry , stereochemistry , organic chemistry , catalysis , materials science , metallurgy
Cycloaddition of sulfene to N,N ‐disubstituted 3‐amino‐2‐methyl‐1‐phenyl‐2‐propen‐1‐ones (I) and 3‐amino‐1,2‐diphenyl‐2‐propen‐1‐ones (II) occurred in good to moderate yield only in the case of aliphatic N ‐substitution to give 4‐dialkylamino‐3,4‐dihydro‐(5‐methyl‐6‐phenyl)(5,6‐diphenyl)‐1,2‐oxathiin 2,2‐dioxides. Polar 1,4‐cycloaddition of dichloroketene to I and II occurred only in the former case, giving in good to moderate yield N,N ‐disubstituted 4‐amino‐3,3‐dichloro‐3,4‐dihydro‐5‐methyl‐6‐phenyl‐2 H ‐pyran‐2‐ones which were dehydrochlorinated with DBN to N,N ‐disubstituted 4‐amino‐3‐chloro‐5‐methyl‐6‐phenyl‐2 H ‐pyran‐2‐ones. In the reaction of 2‐methyl‐1‐phenyl‐3‐diphenylamino‐2‐propen‐1‐one with dichloroketene, a product was isolated which was proven by uv, ir, nmr and chemical evidence to be the dipolar ion VI, the supposed intermediate of the polar 1,4‐cycloaddition of dichloroketene to N,N ‐disubstituted enaminones.