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An efficient stereocontrolled total synthesis of (+)-biotin (1) has been achieved via the intermediacy of Roche's lactone 5 starting from cis-1,3-dibenzyl-2-imidazole-4,5-dicarboxylic acid (2). The bifunctional cinchona alkaloid-derived squaramide-promoted enantioselective alcoholysis was utilizing as a tool for the construction of two contiguous stereocenters of C-3a and C-6a in biotin molecular with excellent enantioselectivity. In addition, the 4-carboxybutyl side chain was assembled by first using C4+C1 approach via a novel tricyclic thiophanium salt intermediate.

A practical and highly regio- and stereoselective synthesis of oligoprenols starting from commercially available geraniol is described. The convergent synthetic strategy features the iterative allyl-allyl coupling of monomers easily derived from geraniol that contain one reacting terminal functional group and the repetitive reductive elimination of the p-toluenesulfonyl (Ts) groups.

A practical, highly stereoselective ten-step synthesis of coenzyme Q10 (1) has been accomplished (overall yield ca. 28%), starting from commercially available 2,3-dimethoxy-5-methylbenzoquinone (Scheme). The introduction of the first side-chain isoprenyl group with (E)-configuration (compound 6) was realized by means of a coupling reaction of the aromatic system 3 with oxirane, followed by Swern oxidation and Wittig olefination. The tosyl (Ts) group in the sulfone 9 was selectively removed with sodium naphthalenide in THF to afford 1.

A practical chemoenzymatic method for the asymmetric total synthesis of d-biotin (1) starting from the commercially available cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) has been developed. The key step of the synthesis is the highly enantioselective hydrolysis of meso-dicarboxylic esters by a polymer-supported pig liver esterase and introduction of a formyl group at the C-4 position in 4 via a Grignard reaction. The polymer-supported PLE can be recovered quantitatively from the reaction mixture by simple filtration and reused without significant loss of activity.

An efficient and highly stereoselective total synthesis of d-biotin has been achieved starting from cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) with an overall yield of 33%. Polymer-supported oxazaborolidine-catalyzed asymmetric reduction of meso-cyclic imide 4 constitutes the key synthetic step in introducing stereogenic centers into the d-biotin molecule.

A concise and efficient TEA-mediated desymmetrization of meso -thioanhydride 6 with 5-ethoxy-5-oxopentylzinc bromine has been developed, which affords a convenient strategy for the stereospecific total synthesis of (±)-biotin 1 .

An improved palladium(II)-catalyzed cleavage of the allyl group in allyl faropenem 2 into faropenem sodium 1 is described. The development of an efficient method for the removal of palladium impurities from the crude product 1 upon treatment with polystyrene-bound 2,4,6-trimercapto-s-triazine (polystyrene-bound TMT) led to a drastic decrease of residual palladium level from 1500−1600 ppm to less than 10 ppm in the final isolated product. The palladium(II)-catalyzed cleavage and palladium removal process demonstrated on 10 kg scale are highly convenient and efficient.

An efficient and highly stereoselective total synthesis of d-biotin has been achieved starting from cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) with an overall yield of 33%. Polymer-supported oxazaborolidine-catalyzed asymmetric reduction of meso-cyclic imide 4 constitutes the key synthetic step in introducing stereogenic centers into the d-biotin molecule.

As part of a series of studies to discover new HIV reverse-transcriptase inhibitors, various novel 6alpha- and 6beta-naphthylthio 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio) thymine (HEPT) derivatives were synthesized, and in vitro anti-HIV-1 activity was evaluated. The results revealed that most of 6alpha-naphthylthio HEPT derivatives (7a-w) showed good activity [for 7e, IC50 value of 0.048 microM and selectivity index (SI) value of 735; for 7h, IC50 value of 0.057 microM and SI value of 579; for 7k, IC50 value of 0.063 microM and SI value of 565], 6beta-naphthylthio HEPT derivatives (8a-f) showed low activity, but the introduction of alpha nitro group to the C-1 position of the 6beta-naphthyl ring in the 6beta-naphthylthio series (11a-c) resulted in a dramatic increase in anti-HIV-1 activity.