ISSN:
0009-2940
Keywords:
Carbenes, nucleophilic
;
Cyclohexadienylidenes
;
Pyrylium ions
;
Carboxonium ions
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Reactions of Vinylogous Oxycarbenes with MethanolThe carbenes 16 and 30 were generated in methanol/sodium methoxide by photolyses of 2-methylchromone tosylhydrazone (14) and 3,5-dimethoxy-4,4-dimethyl-2,5-cyclohexadienone tosylhydrazone (28), respectively. Neither 16 nor 30 accept methanol at the carbenic site to give products of a formal O - H insertion. Carbene 16 affords 2-methoxy-2-methyl-2H-1-benzopyran (19) by way of the benzopyrylium ion 17. The same ether was obtained from the independently prepared perchlorate of 17. Protonation of 30 was followed by demethylation of the delocalized carboxonium ion 31 to give 5-methoxy-6,6-dimethyl-2,4-cyclohexadienone (33) as the only product.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240826
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