First total synthesis of the proposed structure of cryptorigidifoliol B

Total synthesis of nahuoic acid A via a putative biogenetic intramolecular Diels-Alder (IMDA) reaction

Inspired by the biogenetic proposal of an intramolecular Diels-Alder (IMDA) cycloaddition, the total synthesis of natural product nahuoic acid A, a cofactor-competitive inhibitor of the epigenetic enzyme lysine methyl transferase SETD8, has been carried out. A non-conjugated pentaenal precursor was synthesized with high levels of stereoselectivity at seven stereogenic centers and with the appropriate control of double bond geometries. Although the IMDA reaction of the non-conjugated pentaenal using Me2AlCl for catalysis at -40 °C selectively afforded the trans-fused diastereomer corresponding to the Re-endo mode of cycloaddition, under thermal reaction conditions it gave rise to a mixture of diastereomers, that preferentially formed through the exo mode, including the cis-fused angularly-methylated octahydronaphthalene diastereomer precursor of nahuoic acid A. The natural product could be obtained upon oxidation and overall deprotection of the hydroxyl groups present in the Si-exo IMDA diastereomer.

Structure Reassignment of Cryptorigidifoliols E and K

The structures of the α-pyrones cryptorigidifoliols E (5) and K (11) have been reassigned as 5C and 11C.

Biosynthesis-Inspired Total Synthesis of Bioactive Styryllactones (+)-Goniodiol, (6S,7S,8S)-Goniodiol, (-)-Parvistone D, and (+)-Parvistone E

A protecting-group-free total synthesis of (+)-goniodiol (1), (6S,7S,8S)-goniodiol (2), (-)-parvistone D (4), and (+)-parvistone E (6) was efficiently achieved in five steps from commercially available trans-cinnamaldehyde with high overall yields (72-75%). The synthesis strategy was inspired from the proposed biosynthesis pathway of styryllactones. Key transformations of the strategy include a one-pot conversion of goniothalamin oxide to goniodiol or 9-deoxygoniopypyrone in aqueous media, stereoselective epoxidation, ring-closing metathesis, and stereoselective Maruoka allylation. The route is amenable to synthesis of various analogues for biological evaluation.