Organa-aluminium, -gallium and -indium compounds as precursors for semi-conducting thin layers

699-709The fabrication of III-V semiconductor thin films is receiving increasing attention in view of their applications in electronic and optoelectroriic devices. These are produced by employing the chemical vapour deposition (CVD), vapour phase epitaxy (VPE) and other related epitaxial techniques. The conventional precursors for III-V semiconductors are group III trialkyls (MR3, M = AI, Ga, In; R=alkyl or aryl) and group V hydrides (EH3, E=N, P, As, Sb), However, the pyrophoric nature of MR3) and toxic character of EH3 have prompted the development of newer intermolecular and intramolecular organometallic compounds for safer and convenient handling. Nonpyrophoric organometallic compounds of AI, Ga and In have been developed for suitable use with conventional as well as with new organic group V sources for safer application in metal organic chemical vapour deposition (MOCVD) or vapour phase epitaxy (MOVPE) processes

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

Enantioselective organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the most significant synthetic methods reported on chiral-amine-catalyzed tandem Michael conjugate addition of heteroatom-centered nucleophiles to α,β-unsaturated compounds followed by cyclization reactions for the enantioselective construction of functionalized chiral chromenes, thiochromenes and 1,2-dihydroquinolines in optically enriched forms found in a myriad of bioactive natural products and synthetic compounds