Enantiopure Polycycles by Sequential Cycloadditions

Catalytic defluorinative [3 + 2] cycloaddition of trifluoromethylalkenes with alkynes via reduction of nickel(ii) fluoride species

A catalytic synthesis of 2-fluoro-1,3-cyclopentadienes was achieved via [3 + 2] cycloaddition of 2-trifluoromethyl-1-alkenes and alkynes using a nickel catalyst and a diboron-based ternary additive system.

Enantioselective syntheses of candenatenins B and C using a chiral anthracene auxiliary

An asymmetric synthesis of two anticancer natural products, candenatenins B and C, is described, leading to a revision of the originally assigned stereochemistry. The synthesis follows a Diels-Alder/retro-Diels Alder strategy using a chiral anthracene auxiliary to access both targets with 90% ee. The inherent structural qualities of the auxiliary allow for both regio- and diastereoselective transformations.

Diels-Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

Regioselective construction of 4,8,9-trioxygenated 2,3-dihydrobenz[f]indenones, key intermediates for the synthesis of kinamycin antibiotics, was achieved via Diels-Alder reactions (DAR) using 4,7-dioxygenated indanone-type compounds as dienophiles. Reaction of indanetrione with 1-methoxybutadiene gave a 1 : 1 mixture of undesired 4,5,9-trioxygenated 2,3-dihydrobenz[f]indenone and [4.4.3]propellane. The addition of Lewis acid did not affect the product ratio, whereas the use of the 6-bromoindanetrione exclusively afforded the latter propellane. On the other hand, DAR of benzyne derived from bromoindan and furan gave 5,8-epoxy-2,3-dihydrobenz[f]indene, which was subjected to acid-induced ring opening to give 2,3-dihydrobenz[f]indenone with undesired 4,5,9-trioxy functions.

Chiral anthracene and anthrone templates as stereocontrolling elements in Diels–Alder/retro Diels–Alder sequences

The development of chiral anthracene templates for use in Diels-Alder/retro Diels-Alder sequences is described. A summary of past results and new progress is reported.