A study of the bonding in phosphine by an electron impact coincidence experiment

The binding-energy spectrum of phosphine has been obtained over the range 0–30 eV using the binary (e, 2e) coincidence method. The momentum distribut     

The 13C NMR spectra of homoisoflavonoids

The study of a set of 3-benzylidene-4-chromanones, 3-benzyl-4-chromanones, 3-benzyl-3-hydroxy-4-chromanones and 3-benzylchromones (homoisoflavonoids) by ¹³C NMR spectroscopy shows the influence of the structure of these molecules on the chemical shifts of the more characteristic carbon atoms at positions 2, 3 and 4.     

Generic singularities of certain Schubert varieties

Let G be a connected semisimple algebraic group, B a Borel subgroup, T a maximal torus in B with Weyl group W, and Q a subgroup containing B. For , let denote the Schubert variety . For such that , one knows that ByQ / Q admits a T-stable transversal in , which we denote by . We prove that, under certain hypotheses, is isomorphic to the orbit closure of a highest weight vector in a certain Weyl module. We also obtain a generalisation of this result under slightly weaker hypotheses. Further, we prove that our hypotheses are satisfied when Q is a maximal parabolic subgroup corresponding to a minuscule or cominuscule fundamental weight, and is an irreducible component of the boundary of (that is, the complement of the open orbit of the stabiliser in G of ). As a consequence, we describe the singularity of along ByQ / Q and obtain that the boundary of equals its singular locus. Received October 9, 1997; in final form February 19, 1998     

Microwave-assisted efficient synthesis of 1,2-diaryldiketones: a novel oxidation reaction of diarylalkynes with DMSO promoted by FeBr3

This paper reports the oxidation of functionalized diarylalkynes with DMSO in the presence of the environmentally friendly FeBr₃ catalyst. This non-toxic procedure is general and has been applied successfully under microwave irradiation leading rapidly to benzil derivatives in good yields.     

A two-step synthesis of aminopropylpiperidines via aminopropargylpyridines, suitable for the synthesis of a new class of 5-HT4 ligands

A rapid and flexible synthetic approach to {[bis(tert-butoxycarbonyl)amino]propyl}piperidines 5 and related compounds is described. The key step is a three-component coupling process of 2-, 3- or 4-bromopyridine, propargyl bromide and potassium di-tert-butyliminodicarbonate under palladium-copper catalysis leading to 2-, 3- or 4-{[bis(tert-butoxycarbonyl)amino]-propargyl}pyridines 4 followed by a catalytic reduction step.     

Synthesis of substituted quinolines by iron-catalyzed coupling reactions between chloroenynes and Grignard reagents

This letter reports the preparation of quinolines, substituted at the 2- or 3-position by a 4-substituted but-3-en-1-yne group, by the environmentally friendly iron(III)-catalyzed coupling reaction of Grignard reagents with 1-chloro-4-(2-quinolyl)but-1-en-3-yne. The extension and the scope of this non-toxic and chemoselective procedure to various functionalized unsaturated vinyl chlorides are described.     

Stereoretentive Copper‐Catalyzed Directed Thioglycosylation of C(sp2)−H Bonds of Benzamides

An efficient thioglycosylation of C(sp²)?H bonds with thiosugars has been established for the first time. Using only Cu(OAc)₂?H₂O as a catalyst and Ag₂CO₃ as an additive in DMSO, the protocol proved to have broad scope, and a variety of complex thioglycosides have been prepared in good yields with exclusive β‐selectivity.