Martin N. Kenworthy

Axial chirality in xanthene-4,5-dicarboxamides: 1,9-stereocontrol mediated by remote interactions between conformationally constrained amide groups

Abstract Tertiary 9,9-dimethylxanthene-4,5-dicarboxamides have a C 2 -symmetric, axially chiral ground state due to remote interactions between the conformationally constrained tertiary amide substituents. Double ortholithiation–alkylation blocks amide rotation, and the 3,6-dialkylated products are chiral, existing as a pair of enantiomeric C 2 -symmetric atropisomers. Double lateral lithiation–electrophilic quench introduces a pair of 1,9-related stereogenic centres—each under the control of one of the conformationally constrained amides—with complete diastereoselectivity.

Tethered aminohydroxylation using acyclic homo-allylic sulfamate esters and sulfonamides as substrates

Homo-allylic sulfamate esters and sulfonamides are shown to be useful substrates for the tethered aminohydroxylation (TA) reaction. The sulfamate esters undergo the TA reaction delivering 1,2,3-oxathiazinane products whereas the sulfonamides give 1,2-thiazinane products. A range of acyclic homo-allylic sulfamate esters were prepared and subjected to the TA reaction to establish the scope of the process. Nucleophilic ring-opening reactions of the 1,2,3-oxathiazinane products are also described.