HIGHLY REACTIVE EQUIVALENTS OF ALLYLIDENETRIPHENYLPHOSPHORANES FOR THE STEREOSPECIFIC SYNTHESIS OF 1,3-DIENES BY CIS-OLEFINATION OF HINDERED ALDEHYDES
Ylides derived from 3-dimethylaminopropyltriphenylphosphonium salts react smoothly and stereospecifically with even hindered aldehydes to form Z-olefins which are easily converted to 1,3-dienes.
Gold(i)-catalyzed tandem cyclization of cyclopropylidene-tethered propargylic alcohols: An approach to functionalized naphtho[2,3-: C] pyrans
An unprecedented gold(i)-catalyzed cyclization of cyclopropylidene-tethered propargylic alcohols via a 6-endo-dig enyne cyclization followed by a ring-opening of cyclopropane and nucleophilic closure reaction to construct naphtho[2,3-c]pyrans was developed. This transformation represents a highly efficient method for the synthesis of polycyclic compounds in one-pot, and two new rings are formed in an atom economic manner.