6187 determination summary of [TTF] [(CHz),Tcbiim] including tables of bond lengths and bond angles, tables of atomic positions and thermal parameters, and additional crystal-packing diagrams and an ORTEP plot of [TTF][(CH2)zTcbiim] (14 pages): tables of structure factors for C18HsNsS4 (10 pages). Ordering information is given on any current masthead page. helpful discussions and suggestions. We especially thank Professor A. H. Francis and S. Sibley for luminescence spectroscopy measurements. We also thank Dr. J. Kampf for the X-ray crystallography.Abstract: A combined fructose 1,6diphosphate aldolase reaction and catalytic reductive amination has been used in the asymmetric synthesis of azasugars structurally corresponding to N-acetylglucosamine, N-acetylmannosamine, and deoxyhexoses. The 6-deoxyazasugars were prepared by direct hydrogenolysis of the aldolase product without removal of the 6-phosphate group.Both (R)and (S)-3-azido-2-acetamidopropanal used as substrates in the aldolase reactions were prepared from the corresponding lipase-resolved 2-hydroxy species followed by formation of an aziridine intermediate and opening of the aziridine with azide. Evaluation of these azasugars and their diastereomerically pure tertiary amine oxides as well as 5-thioglucose and its sulfoxide derivatives as glycosidase inhibitors was carried out. It was found that all synthetic azasugars and 5-thioglucose were strong inhibitors, but oxidation of the ring heteroatom weakened the inhibition. With the aid of molecular modeling and inhibition analysis, a structure-K; relation of inhibitors was established which provides useful information for the design of new glycosidase inhibitors.Many pyranoses and furanoses with the ring oxygen replaced by an imino group are natural products and useful as potent glycosidase inhibitorse2 This discovery has stimulated interests in the development of effective procedures for the synthesis of various azasugars' and analogues4 for the investigation of glycosidase reactions5 and the development of specific glycosidase ~ ~~ ~~~ ____ (1) Supported by the NIH (GM44154). (2) (a) Paulsen, H.; Tcdt, K. Petursson, S.; Campbell, A. L.; Mueller, R. A.; Behling, J. R.; Babiak, K. A,; Ng, J. S.; Scaros, M. G. J. Chem. Soc., Perkin Trans. 1989,665. (I) Dondoni, A.; Fantin, G.; Fogagnolo, M.; Merino, P.

Communication Ruthenium Olefin Metathesis Catalysts for the Ethenolysis of Renewable FeedstocksRuthenium olefin metathesis catalysts have been evaluated for the ethenolysis of methyl oleate, a natural seed oil derivative, to produce useful terminal olefins. Several N-heterocyclic carbene-based ruthenium catalysts demonstrate good activity and selectivity for the formation of terminal olefins. In particular, catalysts (10) and (21) achieved higher TONs (A20 000).

The first kinetically controlled, highly trans-selective (>98%) olefin cross-metathesis reaction is demonstrated using Ru-based catalysts. Reactions with either trans or cis olefins afford products with highly trans or cis stereochemistry, respectively. This E-selective olefin cross-metathesis is shown to occur between two trans olefins and between a trans olefin and a terminal olefin. Additionally, new stereoretentive catalysts have been synthesized for improved reactivity.

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A synthetic strategy is developed that uses organic phosphate utilizing enzymes as catalysts and a mixture of an organic alcohol and inorganic arsenate or vanadate to replace the organic phosphate substrate. In this process, inorganic arsenate or vanadate reacts with the alcohol reversibly in situ to form a mixture of esters, one of which is accepted by the enzyme as a substrate. Examples of the utility of this approach are demonstrated in enzymatic aldol condensations catalyzed by fructose-1,6-diphosphate aldolase, fuculose-1 -phosphate aldolase, and rhamnulose-l-phosphate aldolase with a mixture of dihydroxyacetone and inorganic arsenate as substrate.Several uncommon sugars and deoxy sugars are prepared on 5-17-mmol scales. Mechanistic studies on an aldol reaction indicate that the redox reaction between dihydroxyacetone and inorganic vanadate prohibits the use of such a mixture to replace dihydroxyacetone phosphate in enzymatic aldol condensations.