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Keywords: 1-Benzoxepine / Sharpless asymmetric dihydroxylation / Cyclic sulfate A new asymmetric synthesis of 2,3-disubstituted 1-benzoxepines is described. Key steps include Sharpless asymmetric dihydroxylation of trans-α,β-unsaturated esters and phenoxide ion mediated intramolecular 7-endo-tet carbocyclization of syn-2,3-dihydroxy ester derived cyclic sulfates.

A series of trisubstituted methanes containing aryl and heteroaryl rings, as well as a sulfur spacer between the central methanocarbon and benzene ring, is reported. In an approach towards asymmetric tetrasubstituted methane with high enantioselectivity, chiral tertiary a-hydroxyaldehyde has been synthesized through a Sharpless dihydroxylation on a disubstituted olefin, followed by the chemoselective oxidation of the primary alcohol.

The enantioselective synthesis of 2-isopropenyl-2,3-dihydrobenzofurans, 4-(2,3-dihydrobenzofuran-2-yl)-2-methylbut-3-en-2-ols, 2-hydroxymethyl chromans, and 4-chroman-2-yl-2-methylbut-3-en-2-ols has been achieved using Sharpless asymmetric epoxidation-derived enantiomerically enriched epoxy alcohols as chiral building blocks. A phenolate ion mediated intramolecular epoxide ring-opening reaction was the key step for every cyclization reaction.