[Show abstract][Hide abstract] ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
[Show abstract][Hide abstract] ABSTRACT: A novel three-component condensation followed by a crystallization-induced asymmetric transformation is used to build this key substance P inhibitor intermediate in a short synthetic sequence.
[Show abstract][Hide abstract] ABSTRACT: The cover picture shows the structures of the complex mixture of isomers obtained from a three-component cyclization of an aryl boronic acid with glyoxal and an aminodiol (left). Crystallization, induced by seeding the mixture, resulted in the transformation of these isomers to the single cis isomer as shown on the right. The background depicts the crystal packing of this cis-lactol as determined by single-crystal X-ray analysis. The compounds are key intermediates for the synthesis of the Merck substance P inhibitors. This work is described in more detail by P. J. Pye and K. Rossen et al. on p. 1372 ff.
[Show abstract][Hide abstract] ABSTRACT: We describe a convergent synthesis of the MRSA β-methyl carbapenem 1, wherein the molecule is assembled from the naphthosultam side chain 2 and the allylic carbonate of the β-Me carbapenem piece 6. The β-Me stereochemistry of 6 is set up in a novel titanium enolate addition into the TBDMS acetoxy azetidinone 5. The benzenesulfonate salt of 1 is endowed with exceptional stability.
No preview · Article · Nov 1999 · Journal of the American Chemical Society
[Show abstract][Hide abstract] ABSTRACT: A highly convergent, asymmetric synthesis of L-768,673, an Iks Class III antiarrythmic drug candidate, is described. Synthesis of the recemic 1-trifluoroethyl-3-amino-5-phenyl benzodiazepinone [(±)-amine] was achieved by Ru-catalyzed hydrogenation of the corresponding oxime that was derived from commercially available 1-trifluoroethyl-5-phenyl benzodiazepine in 76% overall yield. An efficient one-pot resolution-racemization of (±)-amine provided the desired (±)-amine as its mandelate salt in 92% yield and 99.4% ee. Regioselective ortho-lithiation of 1,3-bis(trifluoromethyl)benzene with n-BuLi in the presence of a catalytic amount of 2,2′,6,6′-tetramethylpiperidine afforded its aryl lithium. Subsequent transmetalation and alkylation with allyl bromide produced the corresponding olefin. Ru-catalyzed oxidative cleavage of the terminated double bond of the olefin provided the desired 2,4-bis(trifluoromethyl)phenylacetic acid in 35% overall yield. A modified Schotten-Baumman procedure was developed for coupling of (+)-amine and the acid to produce L-768,673 in 92% yield without racemization.