Harumi Kaga

A GENERAL AND STEREOSELECTIVE SYNTHESIS OF THE CAPSAICINOIDS VIA THE ORTHOESTER CLAISEN REARRANGEMENT

Abstract Capsaicin, a main pungent principle of hot pepper, and its 15 analogs have been efficiently synthesized. The key step of this synthetic sheme is the orthoester Claisen rearrangement, which transformed allylic alcohols 2A-C to (E)-alkenoates 3A-C ( E Z > 100 ) in a highly stereoselective manner. The subsequent carbon chain elongations on 3 based on the cyanation or the malonic acid ester synthesis afforded (E)-alkenoic acids 8, which were converted to the corresponding acid chloride and then coupled with vanillylamine to give capsaicinoids. HPLC and CE (capillary electrophoresis) analyses of these capsaicinoids were also carried out.

Cationic ring-opening polymerization of 1,6-anhydro-2,3,4-tri-O-allyl-β-D-glucopyranose as a convenient synthesis of dextran

For the convenients synthesis of (1→6)-α-D-glucopyranan, i.e., dextran (A), ring-opening polymerization of 1,6-anhydro-2,3,4-tri-O-allyl-β-D-glucopyranose (1) has been carried out using BF 3 -OEt 2 . With a ratio of [BF 3 -OEt 2 ]/[1]= 0.5 at 0°C for 140 h, the yield and M n of the obtained polymer are 84.0% and 21 700, respectively. The polymer consists of (1→6)-α-linked 2,3,4-tri-O-allyl-D-glucopyranose (2) which is similar to the results for the cationic ring-opening polymerization of 1,6-anhydro-2,3,4-tri-O-methyl-β-D-glucopyranose and 1,6-anhydro-2,3,4-tri-O-ethyl-β-D glucopyranose. Polymer 2 was isomerized using tris(triphenylphosphine)-chlororhodium as the catalyst in toluene/ethanol/water to yield polymeric 2,3,4-tri-O-propenyl-(1→6)-α-D-glucopyranan (3). Deprotection of the propenyl ether linkage of 3 was then performed using hydrochloric acid in acetone to give 4.

Identification of the extracellular polysaccharide produced by the snow mold fungus Microdochium nivale

A water-insoluble, extracellular polysaccharide was isolated from the culture medium of the snow mold fungus, Microdochium nivale, that had been cultivated in potato/dextrose broth. The polysaccharide consisted of glucose only. Its Fourier transform infrared spectrum showed a beta configuration of the C1 position of glucose. Linkage analysis of the polysaccharide showed that it had a linear structure of β-(1→4)-linked glucose. The polysaccharide was therefore identified as cellulose. This is the first report of extracellular cellulose occurring in fungi.

Lipase-mediated resolution of cis-1-amino-2-indanol, the key component of the HIV protease inhibitor indinavir

Abstract The efficient and direct resolution of cis -1-amino-2-indanol using Candida antarctica lipase B catalyzing the alcoholysis of its N , O -diacetyl derivative is reported.

Lipase catalyzed transesterification of 2‐substituted 3‐hydroxy esters

Kinetic resolution of 2-substituted 3-hydroxy esters was examined by lipase PS catalyzed transesterification using vinyl acetate as an acyl donor. Resolution of (±)-syn- and -anti-1a, -1e possessing a small methyl group at the C-3 position was accomplished enantioselectively. The outcome of the resolution seems to be related to the differences in size of the substituents at the stereocenter bearing a secondary hydroxy group. Chirality 10:693–698, 1998.

Alignment Photocontrol of a Liquid Crystal by Spirooxazine Monolayers

Abstract In purpose to enhance the sensitivity of liquid crystal (LC) photocontrol by spirooxazine (Sox) monolayer, we report here the effect of N-alkyl residues of Sox on the photochromic behavior in monolayers and their ability to control LC alignment.