Isolation of tetraphenyl-, pentaphenyl-, hexaphenyl-, and heptaphenyl-substituted tetramethylenecyclobutanes. Stable tetraradialenes

The title polyphenyl-substituted tetramethylenecyclobutanes were isolated and their propeller structures were studied by means of NMR spectra.     

Antarafacial role of an aromatic nucleus; a novel regiospecific [π4a + π2a] intramolecular cycloaddition of the ene-ketene with an aromatic ring

The thermally generated ene-ketene undergoes a facile and regiospecific intramolecular cycloaddition with N,N-dimethylaniline to result in the novel formation of the azulenone derivative via a norcaradiene intermediate.     

Novel copper(I) chloride-assisted coupling reaction of 1-chloro-1-aryloyl-3,3-diarylallene to afford 3,7-dioxa-2,6-diaryl-4,8-bis(diarylmethylene)bicyclo[3.3.O]octa-1,5-diene and 1,1,4,4-tetraaryl-3,6-diaryloylhexa-1,2-diene-5-yne,and thermal cyclization of the latter to a fulvene

A novel CuCl-assisted coupling reaction of 1-chloro-1-aryloyl-3,3-diarylallene ($\text{5}$) and two new thermal cyclization reactions of 1,1,4,4-tetraaryl-3,6-diaryloylhexa-1,2-diene-5-yne ($\text{7}$) are described.     

Separation of phenol and cresols by crystalline complexation with 1,1-di(p-hydroxyphenyl)cyclohexane,and crystal structure analyses of the complexes

This paper is concerned with 11 inclusion complexes of the 1,1-di(p-hydroxyphenyl)cyclohexane host with either phenol or one of the cresol derivatives as guest. Selectivity studies showed preferential complexation with a guest according to the sequence;m-cresol > p-cresol > phenol > o-cresol. Crystallographic analyses of the four complexes revealed isomorphous structures [crystal data for the phenol complex:a=6.232,b=10.849,c=14.845 Å, =95.69, =93.49, =104.31°, space groupPl,Z=2]. The intermolecular arrangements are characterized by layers of efficiently hydrogen bonded entities (host-to-host, host-to-guest and guest-to-host) parallel toab, every OH group being involved in two H-bonds. Organization of the layers alongc is stabilized by weak dispersion forces, thus being most sensitive to structural variation of the guest component. The observed features of selectivity upon crystalline complexation are related to differences in topological complementarity between the constituents of each structure. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82052 (4 pages).     

Organogermanium compounds : II. Reduction of organic halides with hydrogermanes

The scope of the reduction of organic halides with trialkylgermanes under homolytic condition has been studied. Germanium hydrides can reduce polyhaloalkane without catalysts under mild conditions, the homolytic mechanism being, however, established for the uncatalyzed reduction. The observed orders of reactivity and selectivity in the reduction are consistent with a radical chain mechanism involving free germyl radicals. Some synthetic applications are described.     

New ring-expansion reactions of hydroxy propenoyl cyclic compounds under palladium(0)/phosphine-catalyzed conditions

[reaction: see text] Palladium(0)-catalyzed one-atom ring-expansion of 1-hydroxy-2,2-dialkyl-1-propenoylindan derivatives has been achieved in the presence of P(o-tolyl)(3) giving 2-hydroxy-3,3-dialkyl-2-vinyl-1-tetralone derivatives in excellent yields. This ring-expansion reaction was applied to a 17-(1-oxo-2-propenyl)-beta-estradiol derivative and furnished a similar ring-expanded product in an excellent yield.     

Nanofilm allotrope and phase transformation of ultrathin Bi film on Si(111)-7x7

Our scanning tunneling microscopy and electron diffraction experiments revealed that a new two-dimensional allotrope of Bi forms on the Si(111)-7x7 surface. This pseudocubic [012]-oriented allotrope is stable up to four atomic layers at room temperature. Above this critical thickness, the entire volume of the film starts to transform into a bulk single-crystal (001) phase, as the bulk contribution in the cohesion becomes dominant. Based on ab initio calculations, we propose that the new allotrope consists of black phosphorus-like puckered layers stabilized by saturating all the p(z) dangling bonds in the film.     

Mechanistic considerations for the consecutive cyclization of 2,3-dibromopropylamine hydrobromide giving a strained molecule, 1-azabicyclo[1.1.0]butane

The effective formation of 1-azabicyclo[1.1.0]butane (2) by treatment of 2,3-dibromopropylamine hydrobromide (1) with n-BuLi could be understood considering a rational reaction pathway via both transition states 10 and 19 based on the intramolecular Br...Li(+) coordination. A similar cyclization pathway starting from N-benzyl-3-bromopropylamine hydrochloride (17) to afford N-benzylazetidine (18) could also be postulated on the basis of a transition state 20 involving the intramolecular Br...Li(+) coordination.