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[摘要]:The diastereoselective auxiliary-based intramol. Michael-type addns. to alkylidene bissulfoxides derived from dithiane and dithiolane were investigated. Utilization of substrates bearing N- and O-nucleophilic functions led to the formation of the resp. cyclic substrates with selectivities of 51:49 to 85:15. Cleavage of the bissulfoxide moiety by a 2-step sequence yielded chiral carbaldehydes. The enantiomerically pure compds. obtained by this procedure, for example, tetrahydropyran-2-carbaldehyde and homopipecolic aldehyde, are hardly accessible by other routes. Both enantiomers of the target mols. are available since the stereochem. information is introduced with readily available D- and L-tartrate. |
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