Convergent synthesis of the [5-7-6-3] tetracyclic core of premyrsinane diterpenes.

The [5-7-6-3] tetracyclic core of premyrsinane diterpenes was convergently synthesized the stereoselective three-component coupling of a 2-propenyl unit, an enone, and an aldehyde, followed by the relay ring-closing metathesis with conformation control of the substrate to construct the 7-membered ring.

Nitrone Formation by Reaction of an Enolate with a Nitro Group.

Ketones with a 2-nitrophenyl group at the α-position were treated with sodium hydroxide in methanol at 60 °C. Under these conditions, enolates derived from the ketones intramolecularly reacted with the nitro group to form a variety of nitrones. Additional experimental results, including the unexpected isolation of -hydroxyindolinone as a byproduct, led to a proposed reaction mechanism, occurring via an α-hydroxyketone.

Ppm Cu Catalyst Enables -Alkylation Followed by C-H Cyclization To Synthesize Substituted Oxindoles.

In this paper, we established highly efficient Cu-catalyzed tandem -alkylation C-H cyclization of α-bromocarbonyls and methacrylamides to produce substituted oxindoles. The maximum turnover number was up to 48 000 with reasonable yield. Although the catalyst loadings were very low, the reaction was not involving radical chain reaction.