Total Synthesis of (–)-Anaferine: A Further Ramification in a Diversity-Oriented Approach

The piperidine ring is a widespread motif in several natural bioactive alkaloids of both vegetal and marine origin. In the last years, a diversity-oriented synthetic (DOS) approach, aimed at the generation of a library of piperidine-based derivatives, was developed in our research group, employing commercially available 2-piperidine ethanol as a versatile precursor. Here, we report the exploration of another ramification of our DOS approach, that led us to the stereoselective total synthesis of (\u2013)-anaferine, a bis-piperidine alkaloid present in Withania somnifera extract. This natural product was obtained in 9% overall yield over 13 steps, starting from a key homoallylic alcohol previously synthesised in our laboratory. Therefore, the collection of piperidine-derivatives accessible from 2-piperidine ethanol was enriched with a new, diverse scaffold

Light harvesting of CdSe/CdS quantum dots coated with β-cyclodextrin based host–guest species through resonant energy transfer from the guests

Films of nano-hybrids based on red emitting CdSe/CdS QDs functionalized with perthiolated \u3b2-cyclodextrin hosting a green emitting nitrobenzoxadiazole derivative show emission harvested by the host\u2013guest organic system through resonant energy transfer from the organic host\u2013guest species to the QD

Light harvesting of CdSe/CdS quantum dots coated with b-cyclodextrin based host-guest species through resonant energy transfer from the guests

Films of nano-hybrids based on red emitting CdSe/CdS QDs functionalized with perthiolated \u3b2-cyclodextrin hosting a green emitting nitrobenzoxadiazole derivative show emission harvested by the host\u2013guest organic system through resonant energy transfer from the organic host\u2013guest species to the QD

N-Acylhydrazines: Future Perspectives Offered by New Syntheses and Chemistry

This is a review of the most recent and useful synthetic methodologies for providing access to di- and trisubstituted hydrazides. New chemistry and new organometallic derivatives of the title compounds offer a new arsenal for the production of new functionalised derivatives, which are also useful as new biologically relevant molecules

Asymmetric Aza-Michael Reactions Catalyzed by Cinchona Alkaloids

The organocatalyzed asym. aza-Michael addn. of hydrazones to cyclic enones has been achieved in good yield and stereoselection using cheap and com. available cinchona alkaloids as catalysts. A systematic study of the influence of the structure of the enone on the stereoselectivity was carried out, leading to optically active products with up to 77% ee. The products can be recrystd. to give nearly enantiopure products, and furthermore it was shown that the products could be reduced to the corresponding 1,3-benzylidenehydrazino alc. derivs. with high diastereoselectivity

Synthesis of hydrazines and hydrazides by reduction of hydrazones and azines

A one-pot procedure for the synthesis of hydrazines and hydrazides involves the redn. of hydrazones RR2NN:CR1R3 or azines R2R4C:NN:CR3R5 [R-R5 = H, alkyl, aryl (at least one is other than H); or R2R4C and R3R5C are cycloaliph. or arom. rings] by Me3N.BH3. Thus, redn. of PhCH:NNMe2 with Me3N.BH3/HCl/xylene and treatment with benzoic, o-toluic, or propionic acid afforded 80-90% PhCH2N(COR)NMe2 (R = Ph, o-tolyl, or Et)

Enantioselective reactions catalyzed by synthetic enzymes. A model for chemical evolution

Polyleucines of various lengths act as enantioselective catalysts in the aldol condensation between cyclohexanone and various aromatic aldehydes. Polyleucine and other polyamino acids behave as synthetic enzymes in the epoxidation of chalcone and other electron-deficient alkenes. Both reactions are of considerable prebiotic significance