444880-01-7Relevant articles and documents
A novel tandem [4++2] cycloaddition-elimination reaction: 2-alkenyl-4,4-dimethyl-1,3-oxathianes as synthetic equivalents for α,β-unsaturated thioaldehydes
Ohsugi, Shin-Ichi,Nishide, Kiyoharu,Node, Manabu
, p. 1859 - 1871 (2007/10/03)
The first tandem cationic [4++2] polar cycloaddition-elimination reaction of 1-thia-1,3-butadienyl cations B with olefins to afford directly 3,4-dihydro-2H-thiopyrans D is described. The cations B were easily accessible by treatment of monothioacetals A, particularly the 2-alkenyl-4,4-dimethyl-1,3-oxathianes 1, with a hard Lewis acid. In this novel reaction, 2-alkenyl-4,4-dimethyl-1,3-oxathianes were utilized as synthetic equivalents for highly reactive α,β-unsaturated thioaldehydes. The effect of geminal dimethyl substituents on the oxathianes 1 and the mechanistic aspect of the reaction are considered. The reaction's asymmetric version was also investigated using a chiral oxathiane 4 derived from (-)-(1R,2R,5R)-2-(1-mercapto-1-methylethyl)-5-methylcyclohexanol. Although the enantioselectivities were moderate, the whole process can be done under odorless conditions.
A novel tandem [4++2] cycloaddition-elimination reaction of 4,4- dimethyl-2-styryl-1,3-oxathianes with olefins
Nishide, Kiyoharu,Ohsugi, Shin-Ichi,Node, Manabu
, p. 371 - 375 (2007/10/03)
A novel tandem [4++2] cycloaddition-elimination reaction of 1,3- oxathianes 1a, b with olefins promoted by titanium tetrachloride to give 3,4- dihydro-2H-thiopyrans 3 was developed. 4,4-Dimethyl-2-styryl-1,3-oxathiane (1a) was used as a synthet
