Palladium nanoparticles supported on Smopex®metal scavengers ascatalyst for carbonylative Sonogashira reactions: Synthesis of α,β-alkynyl ketones

Palladium nanoparticles supported on two Smopex®commercial metal scavengers (1% w/w) have beentested in the carbonylative Sonogashira reactions of aryl iodides with phenylacetylene. Their catalyticactivity has been compared with those of more common catalysts (Pd/C, Pd/-Al2O3). Pd/Smopex®-234resulted especially effective in the synthesis of alkynyl ketones even working with a low amount ofpalladium (0.2–0.5 mol%). Preliminary heterogeneity tests (i.e. hot filtration test, Pd leaching and recycleof the catalyst) have been performed in order to evaluate the catalytic behaviour of this system. Theobtained results seem to indicate that Pd/Smopex®-234 could act as a truly heterogeneous catalyst

Insight in cognitive impairment assessed with the Cognitive Assessment Interview in a large sample of patients with schizophrenia

The Cognitive Assessment Interview (CAI) is an interview-based scale measuring cognitive impairment and its impact on functioning in subjects with schizophrenia (SCZ). The present study aimed at assessing, in a large sample of SCZ (n = 601), the agreement between patients and their informants on CAI ratings, to explore patients' insight in their cognitive deficits and its relationships with clinical and functional indices. Agreement between patient- and informant-based ratings was assessed by the Gwet's agreement coefficient. Predictors of insight in cognitive deficits were explored by stepwise multiple regression analyses. Patients reported lower severity of cognitive impairment vs. informants. A substantial to almost perfect agreement was observed between patients' and informants' ratings. Lower insight in cognitive deficits was associated to greater severity of neurocognitive impairment and positive symptoms, lower severity of depressive symptoms, and older age. Worse real-life functioning was associated to lower insight in cognitive deficit, worse neurocognitive performance, and worse functional capacity. Our findings indicate that the CAI is a valid co-primary measure with the interview to patients providing a reliable assessment of their cognitive deficits. In the absence of informants with good knowledge of the subject, the interview to the patient may represent a valid alternative

The silylformilation of functionalised 1-alkynes in the synthesis of fine chemicals: nanostructured rhodium supported catalysts for the synthesis of b-lactams and b-lactones rings

Transition-metal-catalysed carbocyclisation reactions serve as powerful synthetic methods for the construction of various types of ring systems. In particular rhodium promoted silylformylation of functionalised alkynes performed in the presence of a base directly affords polyfunctionalised β-lactones and β-lactams. Both homogeneous and supported rhodium catalysts showed good catalytic efficiencies in the silylcarbocyclisation process. Nanoclusters of rhodium, generated by means of the metal vapour synthesis techniques and deposited on various matrices, resulted extremely reactive due to the very small dimensions of the metal particles

Synthesis of functionalised b-lactones via silylcarbocyclisation/desilylation reactions of propargyl alcohols

Functionalised β-lactones were prepared starting from propargyl alcohols by means of an efficient rhodium-catalysed silylcarbocyclisation reaction. This process took place in high yields and complete stereoselectivity using DBU as the base, a sterically hindered alcohol and/or hydrosilane. Otherwise, a silylformylation competitive reaction occurred affording 3-hydroxy-2-[(aryldimethylsilyl)methylene]alkanals with complete regioselectivity. Indeed, while α-(aryldimethylsilylmethylene)-β-lactones were generated exclusively starting from an alkynol characterised by two alkyl groups on the propargyl carbon atom, significant amounts of the aldehydes were observed for secondary alcohols. In these cases, the use of ortho-substituted arylsilanes improved the chemoselectivity towards the α-methylene-β-lactones. Such molecules were then successfully converted into α-methylaryl-β-lactones by a fluoride-induced rearrangement of the aryl group that migrates from silicon to carbon with retention of configuration

Synthesis and Reactivity of Silylformylation Products Derived from Alkynes

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 ù position of the aliphatic chain of the alkyne cyclisation products are obtained, while á,â-unsaturated aldehydes are generated from propargyl tosylamides, acetates and benzoates. á-Silylmethylene-â-lactams, prepared from p-tosylamides according to silylcarbocyclisation reaction, can be transformed into the corresponding arylmethyl-â-lactams by means of TBAFinduced 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