Desymmetrisation of meso-diols mediated by non-enzymatic acyl transfer catalysts.

Complementary to enzymatic methods, catalytic enantioselective desymmetrisation of meso-diols (EDMD) by small molecule catalysts has emerged as a powerful tool that provides highly enantioenriched materials of considerable value in organic synthesis. This review traces the evolution of easily accessible catalysts used in the EDMD and compares their performance with the existing enzymatic methods.

Diastereoselective and enantioselective reduction of tetralin-1,4-dione.

BACKGROUND: The chemistry of tetralin-1,4-dione, the stable tautomer of 1,4-dihydroxynaphthalene, has not been explored previously. It is readily accessible and offers interesting opportunities for synthesis. RESULTS: The title reactions were explored. L-Selectride reduced the diketone to give preferentially the cis-diol (d.r. 84 : 16). Red-Al gave preferentially the trans-diol (d.r. 13 : 87). NaBH(4), LiAlH(4), and BH(3) gave lower diastereoselectivities (yields: 76-98%). Fractional crystallization allowed isolation of the cis-diol and the trans-diol (55% and 66% yield, respectively). Borane was used to cleanly give the mono-reduction product. Highly enantioselective CBS reductions afforded the trans-diol (72% yield, 99% ee) and the mono-reduction product (81%, 95% ee). CONCLUSION: Diastereoselective and enantioselective reductions of the unexplored tetralin-1,4-dione provides a very convenient entry into a number of synthetically highly attractive 1,4-tetralindiols and 4-hydroxy-1-tetralone.

Truncated Cinchona alkaloids as catalysts in enantioselective monobenzoylation of meso-1,2-diols.

Readily synthesised quincorine and quincoridine derived chiral diamines efficiently catalyse the asymmetric monobenzoylation of cyclic and acyclic meso-1,2-diols.