The enantioselective synthesis of (2R,3R,4E,8E)-3-hydroxy-2,4,8-trimethyldeca-4,8-dienolide (5) by ring-closing metathesis is described. This compound is an analogue of 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (4) which is a rare 11-membered lactone produced by the fungus, Botrytis cinerea. Mutasynthetic studies with compound 5 using two mutants of B. cinerea led to the isolation of four ...

The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions ('the glucose ends'). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was oxidized with osmium tet...

A divergent asymmetric total synthesis of voacafricines and B, hexacyclic monoterpene indole alkaloids, has been accomplished featuring the following key steps: a) a catalyst-controlled Pictet–Spengler reaction 6-methoxytryptamine with chiral α-ketoester affording 1,1-disubstituted tetrahydro-β-carboline in excellent yield diastereoselectivity; b) oxidative cleavage 3,5-disubstituted cyclopente...

Abstract Polar reactive organometallic species have been key reagents in synthesis for more than a century. Stereodefined 1,2-dimetallated alkenes offer promising synthetic utility; however, few methods are available their preparation due to relatively low stability. Here we report the reductive anti -1,2-dimetallation of alkynes stereoselectively generate trans -1,2-dimagnesio- and 1,2-dialumi...

Activation of cannabinoid receptors inhibits voltage-gated Ca2+ channels and activates K+ channels, reminiscent of other G-protein-coupled signaling pathways that produce presynaptic inhibition. We tested cannabinoid receptor agonists for effects on excitatory neurotransmission between cultured rat hippocampal neurons. Reducing the extracellular Mg2+ concentration to 0.1 mM elicited repetitive,...

The enzymatic potential of the cultured plant cells can be employed for bioconversion purposes. Plant enzymes are able to catalyze regio- and stereo-specific reactions, and therefore can be applied for the production of desired substances. The biotransformation of foreign substrates with suspension cells of Peganum harmala was tested with (±) phenylethyl propionate. The callus cultures of Pegan...

An amidase acting on (R,S)-piperazine-2-tert-butylcarboxamide was purified from Pseudomonas azotoformans IAM 1603 and characterized. The enzyme acted S-stereoselectively on (R,S)-piperazine-2-tert-butylcarboxamide to yield (S)-piperazine-2-carboxylic acid. N-terminal and internal amino acid sequences of the enzyme were determined. The gene encoding the S-stereoselective piperazine-2-tert-butylc...

tert-Butyl thymidylate 3 was prepared from thymidine 1 in six steps and 67% overall yield. When the lithium trianion of 3 (prepared by treatment of 3 with excess LDA and then excess tert-butyllithum) is reacted with electrophiles, trapping occurs stereoselectively from either the alpha- or beta-face depending on the electrophile (Scheme 1). Deuterioacetic acid in deuteriomethanol affords mainly...

BACKGROUND The effect of ketamine on vasodilation mediated by adenosine triphosphate (ATP)-sensitive K(+) channels has not been studied. The present study was designed to determine whether ketamine might stereoselectively affect vasorelaxation induced by an ATP-sensitive K(+) channel opener in the isolated rat aorta. METHODS Rings of the rat aorta with or without endothelium were suspended fo...