1MDA

A triene possessing a 2-furanyl subunit as part of the diene was found to undergo quantitative 1MDA reaction at elevated temperature to give exclusively the c/. j-fused product16. 

MDA reaction of a triene generated in situ by thermally induced cheletropic elimination of sulfur dioxide from a substituted 2,5-dihydrothiophene S,5-dioxide has been described18. 

A-Acylation using carboxylic anhydrides has been used for 1MDA substrate assembly34 35. Reaction of the sodium salt of indole with pentanedioic acid anhydride36 gave 5-indolyl-5-oxopentanoic acid which was converted into 1-[( )-l-oxo-4-(trimethylsilyloxy)-4,6-heptadienyl]indole. Thermolysis gave a single tetracyclic cycloadduct. 

Furans participate as dienes in 1MDA reactions. The reaction of 6-(5-methyl-2-furanyl)-2-hepten-3-one was found to be accelerated by the addition of Florisil55. The reactions were found to be reversible with additional substituents at C-1 and C-2, mixtures of starting material and the two diastereomeric cycloadducts were obtained55. These equilibrium reactions may be displaced to the right by the use of high pressure56,5 . 

Thermolysis of ( , )-3-[2-(2-propynyloxy)phenyl]- and 3-[2-(3-phenyl-2-propynyloxy)phenyl]-2-propenal dimethylhydrazone effected an 1MDA reaction with in situ aromatization64. 

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