A new chiral diol, trans-4,5-bis(2-hydroxyphenyl)-1,3-dioxolane, was synthesized by the reductivecoupling of O-benzylated salicylaldehyde with a low-valenttitaniumreagent followed by acetalization and deprotection. Resolution of the diol was achieved through a sequence of esterification with O-methylmandelic acid, chromatographic separation and purification, and methanolysis.
Photocyclization reactions. Part<b>7</b>. Solvent and substituent effects in the synthesis of dihydrobenzofuranols using photocyclization of α-(2-acylphenoxy)toluenes and ethyl 2-acylphenoxyacetates
作者:Essam Mohamed Sharshira、Takaaki Horaguchi
DOI:10.1002/jhet.5570340634
日期:1997.11
Photocyclization reactions were carried out on α-(2-acylphenoxy)toluenes 1a-e and 2-acylphenoxy-acetates 2a-e in three solvents of different polarity (benzene, acetonitrile and methanol) to examine solvent and substituenteffects on the cyclization of 1,5-biradical intermediates to dihydrobenzofuranols. Irradiation of 1a-e in benzene gave cis-dihydrobenzofuranols cis-4b-e selectively in 14-84% yields