Studies on rare earth 1,3-diketonates

The chelates of various rare earths with acetylacetone, benzoylacetone, dibenzoylmethane, 2-thenoyltrifluoroacetone and dithenoylmethane were prepared and some of their physical properties noted. The ultraviolet absorption spectra in various non-aqueous solvents were measured. Absorption measurements in the visible region showed alterations in absorption intensities and resolution in some of the principal bands, depending on the solvent. The infrared spectra were measured and compared with literature data.     

Asymmetric Total Synthesis of Stagonolide F

A highly convergent stereoselective total synthesis of stagonolide F is described starting from commercially available 5-hexen 1-ol using asymmetric dihydroxylation, Jacobsen^'s hydrolytic kinetic resolution (HKR), regioselective epoxide ring opening with vinyl Grignard reaction, esterification, and ring-closing metathesis (RCM) as key steps.     

First Stereoselective and Concise Synthesis of Rhoiptelol C

The first concise stereoselective total synthesis of diarylheptanoid rhoiptelol C ( 1 ) was achieved from readily available vanillin. The synthesis involves Keck's asymmetric allylation, olefin cross metathesis, and Sharpless asymmetric dihydroxylation reaction as key steps.     

Total synthesis of antifungal gamahonolide A

The first stereoselective total synthesis of gamahonolide A (1) has been accomplished using aminoxylation, Keck allylation, and ring-closing metathesis (RCM) reactions as key steps.     

A practical synthesis of ethyl 1,2,4-triazole-3-carboxylate and its use in the formation of chiral 1′,2′-seco-nucleosides of ribavirin

A practical and efficient synthesis of ethyl 1,2,4-triazole-3-carboxylate ( 6a , R' = H) from ethyl carboethoxyformimidate hydrochloride ( 7 ) is described. Alkylation of this heterocycle with the chloromethyl ethers of 1,3-O-dibenzylbutane-1,2R,3S-triol ( 8a ) and 1,3,4-O-tribenzylbutane-1,2R,3S,4-tetrol ( 8b ), followed by conversion of the ester function to the amide and deprotection, furnished the chiral 1′,2′-seco-nucleosides of ribavirin, 11a and 11b , respectively.     

A Short Synthesis of d-Sotalol

Asymmetric synthesis of d-Sotalol (2) was accomplished by chiral homogenous hydrogenation of (4-isopropylaminoacetyl)methane-sulfonanilide hydrochloride (1).     

Oxidative Prins and Prins/Friedel-Crafts cyclizations for the stereoselective synthesis of dioxabicycles and hexahydro-1H-benzo[f]isochromenes via the benzylic C-H activation

1-Benzyl ethers of (E)- and (Z)-hex-3-en-1,6-diols and hept-3-en-1,7-diols undergo a smooth oxidative cyclization with DDQ in the presence of In(OTf)(3) through a sequential C-H bond activation and an intramolecular Prins cyclization to afford the corresponding trans- and cis-fused hexahydro-2H-furo[3,2-c]pyrans and octahydropyrano[4,3-b]pyrans respectively in good yields with an excellent stereoselectivity. Aryl tethered homoallylbenzyl ethers such as benzyl ethers of (E)- and (Z)-6-arylhex-3-enyl alcohols undergo a tandem Prins/Friedel-Crafts cyclization in the presence of stoichiometric amounts of DDQ and SnCl(4)via the benzylic C-H bond activation to furnish the corresponding trans- and cis-fused hexahydro-1H-benzo[f]isochromenes in good yields with complete stereoselectivity.