1426819-10-4Relevant articles and documents
Formal total synthesis of (-)-taxol through Pd-catalyzed eight-membered carbocyclic ring formation
Hirai, Sho,Utsugi, Masayuki,Iwamoto, Mitsuhiro,Nakada, Masahisa
supporting information, p. 355 - 359 (2015/02/19)
A formal total synthesis of (-)-taxol by a convergent approach utilizing Pd-catalyzed intramolecular alkenylation is described. Formation of the eight-membered carbocyclic ring has been a problem in the convergent total synthesis of taxol but it was solved by the Pd-catalyzed intramolecular alkenylation of a methyl ketone affording the cyclized product in excellent yield (97 %), indicating the high efficiency of the Pd-catalyzed intramolecular alkenylation. Rearrangement of the epoxy benzyl ether through a 1,5-hydride shift, generating the C3 stereogenic center and subsequently forming the C1-C2 benzylidene, was discovered and utilized in the preparation of a substrate for the Pd-catalyzed reaction.
A short and enantioselective preparation of taxol A-ring fragment
Hirai, Sho,Urushizako, Naoko,Miyano, Masayuki,Fujii, Tomohiro,Nakada, Masahisa
, p. 1888 - 1892 (2013/04/23)
Two short preparations of the taxol A-ring fragment are described: one via organocatalyzed α-aminoxylation and the other via Sharpless asymmetric dihydroxylation (SAD). The former approach affords the A-ring fragment in 10 steps, and the latter approach involves eight steps to afford the new A-ring fragment in 91% ee, which is made enantiomerically pure through recrystallization. The new A-ring fragment bearing a bromoalkene is confirmed to be useful to form the carbocyclic eight-membered ring of a taxol model compound by palladium-catalyzed intramolecular alkenylation. The preparation of the new A-ring fragment will be beneficial for the total synthesis of taxol as well as other natural products.
