Total Synthesis of Diterpenoid Quinone Methide Tumor Inhibitor, (+)-Taxodione.

An asymmetric polyene cyclization (92% ee) strategy has been successfully applied for the first asymmetric total synthesis of oxidized abietane, anticancer agent, taxodione (1) sharing a trans-decalin system. Additionally, the total syntheses of pomiferin B (2) and gaultheric acid (3) (a nor-abietane) were achieved utilizing this unified approach.

Total synthesis of atropisomeric indolosesquiterpenoids via N-N bond formation: dixiamycins A and B.

N-N dimeric indolosesquiterpene alkaloids constitute a class of under-investigated architecturally intriguing natural products. Herein, we report the first chemical oxidation approach to the asymmetric total syntheses of these atropisomeric indolosesquiterpenoids through N-N bond formation. Specifically, dixiamycins A (1a) and B (1b) were prepared through a Cu(i)-mediated aerobic dehydrogenative dimerization from the naturally occurring monomer xiamycin A methyl ester (2b); this preparation also represents the first total synthesis of dixiamycin A (1a). The monomer xiamycin A methyl ester (2b) was synthesized via a late-stage Buchwald Pd(ii)-mediated aerobic dehydrogenative C-N bond formation.

Total syntheses of naturally occurring antiviral indolosesquiterpene alkaloids, xiamycins C-F via Csp3-H functionalization.

Concise total syntheses of naturally occurring antiviral indolosesquiterpene alkaloids, xiamycin C (2a), D (2b), E (2c) and F (2d), have been achieved via a late-stage oxidative δ-Csp3-H functionalization of an advanced pentacyclic enone intermediate 8. This strategy takes advantage of ipso-nitration of naturally occurring abietane diterpenoids to synthesize o-bromo nitroarene derivative 11. A Suzuki-Miyaura coupling of 11 with phenylboronic acid followed by Cadogan's ring closure provided a modular approach to a carbazole ring required for a functionalized pentacyclic core of indolosesquiterpene alkaloids.

Pd(0)-Catalyzed Chemoselective Deacylative Alkylations (DaA) of N-Acyl 2-Oxindoles: Total Syntheses of Pyrrolidino[2,3- b]indoline Alkaloids, (±)-Deoxyeseroline, and (±)-Esermethole.

We report an efficient Pd(0)-catalyzed deacylative allylation of N-acyl 3-substituted 2-oxindoles via the coupling of in situ generated nucleophiles (3 and 4) with allyl electrophiles for the synthesis of a variety of 2-oxindoles with C3-quaternary centers. Gratifyingly, this alkylation process is found to be highly chemoselective in nature, where a C-C bond formation is completely predominant over a C-N bond formation. A variety of key intermediates were synthesized utilizing an aforementioned methodology.

A catalytic N-deacylative alkylation approach to hexahydropyrrolo[2,3-b]indole alkaloids.

A versatile unprecedented strategy to diversely functionalized hexahydropyrrolo[2,3-b]indole alkaloids is described in high chemical yields. The synthesis features a key Pd(0)-catalyzed deacylative alkylation of N-acyl 3-substituted indoles using only 1 mol% of Pd(PPh3)4. The scope of this methodology is further defined in the asymmetric synthesis of pyrroloindolines using a diastereoselective approach.