Search

Various N-tosyl arylimines reacted with methyl vinyl ketone and ethyl vinyl ketone in the presence of ion-supported Ph3P A and B to give adducts, N-(2′-methylene-3′-oxo-1′-arylbutyl)-4-methylbenzenesulfonamides and N-(2′-methylene-3′-oxo-1′-arylpentyl)-4-methylbenzenesulfonamides, respectively, in good yields with high purity by simple diethyl ether extraction of the reaction mixture. Moreover, ion-supported Ph3P A and B could be repeatedly used for the same reaction to provide the corresponding adducts while maintaining good yields with high purity.

Reactions of salicyl N-tosylimines with methyl vinyl ketone, ethyl vinyl ketone or phenyl vinyl ketone proceeded smoothly under mild conditions to give the corresponding chromanes or aza-Baylis–Hillman adducts in moderate to excellent yields in the presence of phosphine or nitrogen Lewis base.

Two effective synthetic approaches to (±)-euryfuran 1 are described. One synthetic route makes use of sequential furan ring transfer reaction type I and type III as key steps followed by Eschenmoser-type [3,3]sigmatropic rearrangement, and another route proceeded through furan ring transfer reaction type I and annulation with ethyl vinyl ketone subsequently.

In a synthetic approach to the polyhydroxyagarofurans found throughout the family Celastraceae, the Robinson annulation of hydroxycarvone with ethyl vinyl ketone has been repeated. In contrast to the reported results 10-epieudesma-4,11-diene-3,9-dione is the major product (43%) of the annulation and eudesma-4,11-diene-3,9-dione is a minor product (24 %). The structure and stereochemistry of these isomers was determined by conversion to eudesmane derivatives of known structure and stereochemistry. The requisite isomer from the annulation, 10-epieudesma-4,11-diene-3,9-dione, was converted to 9-keto-α-agarofuran by epoxidation with m-chloroperoxybenzoic followed by reduction to a Stereoisomeric mixture of 10-epieuclesm-4-en-3,9,11-triols. Oxidation of this mixture with Jones reagent afforded the ketoagarofuran. This annulation and agarofuran synthesis has also been carried out using hydroxy-carvone and methyl vinyl ketone to afford 14-nor-9-keto-α-agarofuran.

α-Acyloxy derivatives of straight-chain aliphatic sulfides in boiling t-butyl alcohol give mercaptals. Thus, α-benzoyloxy di-n-propyl sulfive and α-acetoxy di-n-butyl sulfide yielded propio-aldehyde di-n-propyl mercaptal and butyroaldehyde di-n-butyl mercaptal, respectively. However, 2-benzoyloxytetrahydrothiophene gave a dimer of dihydrothiophene. Pyrolysis in absence of alcohol of acyloxy derivatives of sulfides results in unsaturated sulfides. Thus, α-acetoxy and α-benzoyloxy derivatives of diethyl sulfide and tetrahydrothiophene yielded ethyl vinyl sufide and 2,3-dihydrothiophene, respectively.