ABSTRACT
An efficient enantioselective synthesis of (+)-isofregenedol was achieved in 13 steps from commercially available cyclohexene oxide without the use of protecting groups. The tetrahydronaphthalenic core of isofregenedol was obtained via a gold(I)-catalyzed benzannulation recently developed in our laboratory.
Subject(s)
Cyclohexenes/chemistry , Naphthalenes/chemical synthesis , Catalysis , Gold/chemistry , Molecular Structure , Naphthalenes/chemistry , StereoisomerismABSTRACT
[reaction: see text] The acid-mediated Prins/pinacol and the triple domino reactions Diels-Alder/Prins/pinacol were used to construct highly functionalized bicyclo[m.n.1]alkanones 19-29 and 33a-c possessing various ring sizes from ketals 8-18 and 31a-c in 44-96% yields. This approach proves to be highly efficient and reliable to generate high molecular complexity in a single step.
ABSTRACT
Lewis-base-catalyzed cycloisomerization of bis(enones) to decalins has been demonstrated as an alternative to the traditional Lewis acid catalyzed Diels-Alder cycloaddition. In this process, a trialkylphosphine mediates both bond formation steps in two distinct catalytic cycles. The single-pot operation generates two carbon-carbon bonds and up to five contiguous stereocenters in one step, starting from achiral, aliphatic substrates; eight examples are provided. [reaction: see text]
ABSTRACT
An efficient method for intermolecular N-arylation of oxazolidinones using Pd(2)dba(3) and various phosphine ligands in the presence of a weak base is reported. The conditions allow the use of cheaper aryl chlorides containing functionalities such as enolizable ketones, amides, etc., which would be incompatible with other coupling methods. The coupling reaction can be used to prepare enantiopure N-aryl beta-amino alcohols. Depending on the stereoelectronic nature of the aryl chloride, careful choice of ligand was necessary for the success of these reactions. [reaction: see text]