Ralph A. Massy-Westropp

Novel monoterpene disaccharide glycosides of Vitis vinifera grapes and wines

Abstract β-Rutinosides (6-O-α- l -rhamnopyranosyl-β- d -glucopyranosides) and 6-O-α- l -arabinofuranosyl-β- d -glucopyranosides of geraniol, nerol and linalol have been isolated and characterized in Muscat of Alexandria grapes and wine. These monoterpene disaccharide glycosides, which are precursors of linalol oxidation state monoterpenes of the grape, are also present in another non-muscat Vitis vinifera var. Rhine Riesling.

Use of C18 reversed-phase liquid chromatography for the isolation of monoterpene glycosides and nor-isoprenoid precursors from grape juice and wines

Abstract Glycosidic derivatives of monoterpene flavourants of grapes and wines can be preparatively isolated by selective retention on a C 18 -bonded reversed-phase adsorbent. These components can thus be concentrated by a factor of 20,000 in a single chromatographic step. Class separation of monoterpene glycosides at different oxidation levels can also be achieved on the reversed-phase adsorbent. Teh process has also led to the discovery of precursors of 2-phenylethanol, benzyl alcohol, damascenone, vitispirane and 1,1,6-trimethyl-1,2-dihydronaphthalene. Additionally, many other related nor-isoprenoid compounds not previously known in grapes have been observed.

Glycosides of 2-phenylethanol and benzyl alcohol in Vitis vinifera grapes

Abstract β-Rutinosides and 6- O -α- l -arabinofuranosyl-β- d -glucopyranosides of 2-phenylethanol and benzyl alcohol have been found to co-occur with similar disaccharide glycosides of monoterpenes in Vitis vinifera vars. Muscat of Alexandria and Rhine Riesling. β- d -Glucopyranosides of these two alcohols were also identified in the fruit.

Precursors of damascenone in fruit juices

Abstract The acid catalysed reactions of 6,7-megastigmadiene-3,5,9-triol and the β-D-glucosides of 5-megastigmen-7-yne-3,9-diol and 3-hydroxyl-β-damascone have been studied in relation to the formation of damascenone. The results show that hydrolysis of the allene triol could account for damascenone formation in the juices of grapes and other fruits.

The asymmetric synthesis of α-amino acids via the addition of grignard reagents to imine derivatives.

Abstract The ester-8-phenylmenthyl N-Boc-glycinate 5a, undergoes free radical bromination by N-bromosuccinimide to give 8-phenylmenthyl N-Boc-bromoglycinate 8. Treatment of the bromide 8 with a variety of Grignard reagents at low temperature gave 8-phenylmenthyl (S-N-Boc-2-alkylglycinates with high diastereoselectivity. Conditions were found for the hydrolysis of these derivatives with no racemization of the resultant amino acid.

Asymmetric induction in acyclic radical reactions: Enantioselective syntheses of α-amino acids via carbon-carbon bond forming radical reactions

Abstract The derivative of glycine, 8-phenylmenthyl N-Boc-2-bromoglycinate 1 reacted with allyltri-n-butylstannanes via the corresponding radical 2 by the SH2′ mechanism to give (2S) allyl amino acid drrivatives with high diastereoselectivity. The reaction of 1 with triphenyl(1,2-propadienyl)stannane and triphenyl(2-propynyl)stannane gave the (2S) allenyl and (2S) propargyl amino acid derivatives respectively also with high diastereoselectivity but by a different mechanism.

Enantioselective syntheses of α-amino acids via carbon–carbon bond forming radical reactions

The derivative of glycine, 8-phenylmenthyl N-Boc-2-bromoglycinate 2 reacts with unsaturated stannanes to give unsaturated amino acid derivatives with high diastereoselectivity.

Asymmetric induction in acyclic radical reactions: enantioselective syntheses of (s)-2-deuterioglycine and (r)-2-deuterioglycine.

Abstract The (-)-8-phenylmenthol esters of N-Boc-glycine and N-Boc-2,2-dideuterioglycine were brominated with N-bromosuccinimide and the bromo compounds were reduced with tri-n-butyldeuteriostannane and tri-n-butylstannane respectively, to give the chiral glycine derivatives in 90% optical yield. Hydrolysis yielded the amino acid without racemisation.

Serrulatane diterpenes from Eremophila duttonii

Abstract Two serrulatane diterpenes have been isolated from Eremophila duttonii . The structure of (3 R )-serrulat-14-ene-3,7,8,20-tetraol, a compound suitable for conversion into the seco -pseudopterosins, was established on the basis of spectroscopic and chemical evidence. Further data are provided for serrulat-14-ene-7,8,20-triol and its derivatives.

Enantioselective syntheses of 2-arylpropanoic acids: (S)-2-phenylpropanoic acid

Abstract (S)-2-Phenylpropanoic acid, an intermediate for the preparation of optically active Ibuprofen, has been synthesized using, as the key steps, Sharpless epoxidation and benzylic hydrogenlysis.