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Cyclocarbonylative Sonogashira reactions of ortho-ethynylbenzamides have been investigated. The process is carried out under CO pressure, in the presence of a very small amount of PdCl2(PPh3)2(0.4 mol %) as a catalytic precursor and without the need for a Cu salt as the co-catalyst. 2-Ethynylbenzamide reacted successfully with iodoarenes bearing electron-withdrawing and electron-donating groups, giving rise to different classes of compounds depending on the solvent used. On the contrary, N-(4-chlorophenyl)-2-ethynylbenzamide afforded exclusively polyfunctionalized isoindolinones with high stereoselectivity toward (E) isomers.

The silylformylation reaction of unsaturated compounds consists of the rhodium-catalysed addition of a R3Si and a CHO moiety to a carbon–carbon multiple bond. The silylformylation process is applicable to both terminal and internal alkynes and is tolerant towards several functional groups. Many factors can influence the chemoselectivity of the reaction that generally affords β-silylalkenals with high yields and regioselectivity. The β-silylalkenals are polyfunctionalised substrates that can be submitted to several chemical transformations and in particular can undergo fluoride-promoted (TBAF) aryl migration from an aryldimethylsilyl group to the adjacent carbon atom thus generating 2-(arylmethyl)aldehydes, important industrial precursors of perfumes. This silylformylation-aryl migration two-steps sequence can be applied to functionalised alkyne precursors and chemo-, regio- and stereoselectivity of the products can be modulated according to the nature and the position of the functional group. When a good leaving group is present in the ω position of the aliphatic chain of the alkyne cyclisation products are obtained, while α,β-unsaturated aldehydes are generated from propargyl tosylamides, acetates and benzoates. α-Silylmethylene-β-lactams, prepared from p-tosylamides according to silylcarbocyclisation reaction, can be transformed into the corresponding arylmethyl-β-lactams by means of TBAF-induced rearrangement that takes place without involving the lactam ring. A plausible mechanism of the rearrangement reaction is reported that suggests the addition of the fluoride ion to the arylsilicon moiety and the consequent migration of the aryl group to the adjacent carbon atom. Both aryl and heteroaryl substituents can migrate without any loss of configuration further enhancing the high synthetic value of this protocol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Polyfunctionalised aldehydes and dihydropyrans are prepared from easily available functionalised 1-alkynes through a two-step silylformylation/aryl migration sequence. The silylformylation process is performed under mild experimental conditions and affords the corresponding β-silylalkenals in high yields. The fluoride-promoted migration step occurs instantaneously with quantitative conversion. The chemo-, regio- and stereoselectivity can be modulated according to the nature and the position of the functional group on the acetylene precursors. When a good leaving group is present in the ω position of the aliphatic chain of the alkyne a cyclisation product is obtained, while α,β-unsaturated aldehydes are generated from propargylic tosylamides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Solvated rhodium atoms, prepared by the metal vapour synthesis technique, promote the silylformylation reaction of variously substituted alkynes R¹R²CH(CH2)nC≡CH, with catalytic activities comparable with and even higher than more common species such as Rh4(CO)12. Z-Silylalkenals are exclusively formed in high yields (60−95%) indicating syn addition both of CO and of the silane (Me2PhSiH) to the triple bond. The chemoselectivity of the process (silylformylation vs. hydrosilylation) is highly affected by the amount of catalyst employed (mmol of Rh species with respect to the alkyne reagent), by the steric requirements of the acetylenic substrates and by the hydrosilane/alkyne molar ratio. When optically active acetylenes are treated in the presence of Me2PhSiH under carbon monoxide pressure, the silylformylation reaction occurs with total retention of stereochemistry of the stereogenic centre, even if it is at the α-position of the unsaturated moiety, to afford enantiomerically enriched β-silylalkenals.

the synthesis of 2-phenylsulphonyltetrahydrofuran (1), 2-phenyl sulphonyl-5-methoxy-2,5-dihydrofuran (2) and 2-phenylsulphonylfuran (3) was carried out in very good yields and short reaction times starting from easily available precursors.

vic-dibromides are quantitatively convened into alkenes by using a catalytic amount of NidppeCl2, in the presence of two molar equivalents of EtMgBr in THF. Stereochemical aspects of the reaction are given.

a catalytic amount of NidppeCl2converts an acyl bromide directly into ketones at 0 °C in THF in the presence of a Grignard reagent. The described procedure represents a useful way to afford dialkyl, diaryl or alkyl aryl ketones as well as 1,2-diketones. In the adopted reaction conditions double bonds, esters and ketones are unaffected.

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.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

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.

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.