As tereocontrolled [4+ +1] annulation of ahydroxycyclobutenonesh as been disclosed. Fort he first time, a-hydroxycyclobutenones have been proven as facile diene precursors for [4+ +1] annulation. Meanwhile,t he reported transformation presents ac oncise synthetic route to polysubstituted cyclopentenones with high stereoselectivity.

Cephalotaxus diterpenoids represent a class of attractive natural products with diverse chemical structures and valuable biological activities. The Construction of tetracyclic core skeleton plays an important role in synthesizing these compounds. We report here the development of diastereoselective Pauson-Khand reactions as an effective strategy to the core structure, which enabled the total synthesis of (+)-3-deoxyfortalpinoid F, (+)-fortalpinoid A, and (+)-cephinoid H.

Metrics & More Article Recommendations * sı Supporting Information ABSTRACT: (−)-Ceforalide B (1) and (−)-cephanolides B−D (2−4) are benzenoid cephanolide diterpenoids possessing the same pentacyclic skeleton, which contains three C 13 −C 15 substituent patterns and different benzylic oxidation states. An olefination/6π-electrocyclization/oxidative aromatization cascade has been verified as divergent access to three C 13 −C 15 patterns. The benzylic aerobic oxidations enabled by the Co(OAc) 2 •4H 2 O/ bromide salt/O 2 /PPh 3 /N-hydroxyphthalimide system have been developed to deliver expected site-selectivity and different oxidation states. Through the divergent strategy, total synthesis of (−)-ceforalide B and (−)-cephanolides B−D is accomplished.