Total synthesis of attenols A and B

A concise approach for the total synthesis of attenols A and B is described involving MacMillan’s α-aminooxylation, Evan’s asymmetric alkylation, Brown’s allylation, and spiro-ketalization as key steps. This approach has successfully demonstrated the α-aminooxylation protocol for the construction of the anti-1,3-diol unit.     

A novel Prins-alkynylation reaction for the synthesis of 4-phenacyl tetrahydropyrans

Aldehyde, homoallylic alcohol, and alkyne undergo smooth Prins-type cyclization in the presence of BF₃·OEt₂/CuCl (10 mol % each) in dichloromethane under mild reaction conditions to afford 4-phenacyl tetrahydropyran derivatives in good yields. This method is highly stereoselective, affording cis-tetrahydropyrans exclusively. The salient features of this method are high conversions, mild reaction conditions, short reaction times, high selectivity, and operational simplicity.     

The stereoselective total synthesis of (−)-cleistenolide

The stereoselective total synthesis of (−)-cleistenolide is described employing the Barbier allylation, MacMillan α-hydroxylation, Stille-Gennari olefination, and CeCl₃·7H₂O mediated lactonization as key steps.     

A novel strategy for the chiral 2,4,5-triol moiety and its application to the synthesis of seimatopolide A and (2S,3R,5S)-(−)-2,3-dihydroxytetradecan-5-olide

A highly stereoselective approach to the total synthesis of seimatopolide A and (2S,3R,5S)-(−)-2,3-dihydroxytetradecan-5-olide is described via a common polyketide precursor by means of Prins reaction and MacMillan aminoxylation sequence.     

Stereoselective total synthesis of xyolide

A stereoselective total synthesis of xyolide is described employing MacMillan α-hydroxylation, Steglich esterification, and ring closing metathesis as key steps. The use of organocatalytic MacMillan α-hydroxylation to construct two of the chiral centers of the xyolide makes this approach attractive.     

Enantioselective total synthesis of macrosphelides A and E

Enantioselective synthesis of 16-membered trilactone macrolides, macrosphelide A and E from (S)-lactic acid is described. Key features of the synthesis include the utility of a hitherto unexplored β-ketophosphonate derived from lactic acid and Yamaguchi lactonization leading to the title compounds.     

A New Stereoselective Total Synthesis of Phomonol

A stereoselective total synthesis of phomonol, following organocatalytic enantioselective epoxidation and intramolecular oxa‐Michael reaction as key steps, is described. The use of readily available D ‐tartaric acid as a chiral source renders this approach quite simple and attractive.     

Novel approach towards one pot stereospecific synthesis of carbohydrate derived substituted imidazolines

A simple synthetic approach has been developed towards one pot synthesis of 2-imidazolines under mild acidic conditions from N-acetyl glucosamine via reductive amination followed by dehydrative cyclization. Synthetic studies were explored in detail with different amines and sugar derivatives. While the conversion was good, the corresponding substituted imidazolines were obtained in moderate yields.     

Total synthesis of (+)-phomopsolide B

An enantiospecific total synthesis of polyhydroxy δ-pyrone natural product phomopsolide B is accomplished. The main feature of the synthesis is the installation of the required E-olefin by Horner–Emmons–Wordsworth reaction and the formation of the lactone involving Still–Gennari olefination followed by lactonization.     

Cloning, Expression and Characterization of NADP-Dependent Isocitrate Dehydrogenase from Staphylococcus aureus

The Krebs cycle dictates oxidative and reductive conditions in Staphylococcus aureus and is mainly regulated by isocitrate dehydrogenase (IDH) which plays pivotal role in the growth and pathogenesis of the bacteria. In the present study, IDH gene from S. aureus ATCC12600 was cloned in the Sma I site of pQE 30 vector; the resultant clone was named as UVIDH1. The insert in the clone was sequenced (accession number HM067707), and the sequence showed complete homology with IDH sequence of other S. aureus strains reported in the database indicating presence of single enzyme in S. aureus, and considerable sequence homology with other bacteria was observed; however, only 24 % homology was found with NADP-dependent human IDH. Phylogenetically, the S. aureus IDH showed close identity with Bacillus subtilis and high degree of variability with other bacteria and human IDH. The expression of IDH in the clone UVIDH1 was induced with 1 mM IPTG, and the recombinant IDH was purified by passing through nickel metal chelate column; the purified recombinant IDH showed a single band in SDS–PAGE with a molecular weight of 40 kDa; K _m and V _max for isocitrate are 8.2?±?0.28 and 525?±?25 μM NADPH/mg/min, respectively, and for cofactor NADP 67.5?±?2.82?μM and V _max 50.5?±?2.12 μM NADPH/mg/min.