Cyclisations involving 1,3-dithiane-derived anions are nor- mally based on intramolecular alkylation reactions. 1 The only literature examples of ring closure via dithianyl anion to carbonyl addition involve the use of 2-trimethylsilyl-dithianes and fluoride-induced cyclisation.2 The problem with the direct cyclisation of 2-(o-oxoalkyl)-dithianes is that the strong bases required for dithiane deprotonation would normally be expected to undergo preferential reaction with the ...
