SYNTHESIS OF β-TRIMETHYLARSONIUMLACTATE

Abstract

The biochemistry of arsenic is of considerable interest owing to the widespread presence of the element in marine organisms.¹ The substance arsenobetaine (Me₃-As⁺CH₂CO₂ ^?) has been isolated from the tail muscle of the western rock lobster (Panulirus longipes cygnus) and from the flesh of the dusky shark (Carcharhinus obscurus) and subsequently characterized by independent synthesis and X-ray crystal structure analysis.² In addition, two arsenic-containing ribose derivatives have been isolated from the brown kelp Ecklonia radiata, which is part of the coastal ecosystem to which the rock lobster belongs.³ Assimilation, reduction, and methylation of arsenate also occurs in photosynthetic marine organisms,^4,5 particularly in phosphate-depleted tropical waters, and in molluscs and ascidians, where arsenic accumulation was found to be greatest in organisms bearing symbiotic algae.⁵ Marine algae cultured in [⁷⁴As] arsenate synthesize an arsenic-containing phospholipid.⁶ Base-catalysed deacylation of the lipid, followed by acid or enzyme hydrolysis of the intermediate phosphodiester, produced a product believed to be the β-trimethylarsoniumlactate, (4). However, a rigorous chemical characterization of the novel zwitterion was not undertaken. Accordingly, we describe here the synthesis of (4), together with some of its properties.     

A NEW SYNTHESIS OF 1-SUBSTITUTED β-CARBOLINES

A new method to tetrahydro-β-carbolines(βCs) from tryptamine is described and the aromatization of THβCs to βCs by manganese dioxide is reported for the first time in this type of compounds.     

AN IMPROVED SYNTHESIS OF ENANTIOPURE β-AMINO ACIDS

An improved method for the preparation of both the enantiopure β-amino acids is presented. The diastereomer benzyl β-amino esters, obtained by stereoselective reduction of β-enamino esters, were separated and hydrogenolyzed to the free enantiopure β-amino acids.     

CHINESE JOURNAL OF CHEMISTRY

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