title: Stereocontrolled synthesis of complicated oxacyclic compounds via platinum-catalyzed [4 + 2]-cycloadditions and annulations of enynals with allylic alcohols.
abstract: We report stereoselective synthesis of tricyclic ketals through Pt(II)-catalyzed [4 + 2]-cycloaddition of benzopyrilium/1-en-3-ol functionalities. For nonaromatic enynals, we obtained distinct tricyclic oxacyclic ketones due to occurrence of a new annulation reaction. This work reports the first example that [4 + 2]-cycloadducts are successfully intercepted from such functionalities in diversified approaches. The value of such cycloadditions and annulations are shown by their high diastereoselectivities and chemoselectivities.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Yu-Chia
authors.initials: YC
authors.lastname: Hsu
authors.forename: Chun-Ming
authors.initials: CM
authors.lastname: Ting
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu