Diels–Alder Cycloadditions of Masked o-Benzoquinones with Alkenes
摘要:
Diels-Alder cycloadditions of 3-oxobut-1-enyl substituted orthoquinone monoketals with olefinic dienophiles furnished functionalized ortho-(e)ndo bicyclo[2.2.2]octenone derivatives with high regio- and stereoselectivities. The competition between self-dimerization and Diels-Alder cyclo-addition with an external dienophile usually exists, except in the case of 5-substituted orthoquinone monoketal.
Syntheses and X-Ray Crystal Structures of Cassiferaldehyde and Analogs
摘要:
Cassiferaldehyde, a recently discovered naturally occurring tyrosinase inhibitor, and six of its analogs, in which the aldehyde group has been replaced by various other functionalities, have been synthesized by a short and simple sequence starting from 2,3-dihydroxybenzaldehyde. Single-crystal x-ray structures of cassiferaldehyde as well as its methyl ketone, nitrile, and carboxylic acid analogs are reported.