Stereocontrolled Access to Quaternary Centers by Birch Reduction/Alkylation of Chiral Esters of Salicylic Acids.

8-Phenylmenthol esters of salicylic acid derivatives undergo efficient Birch reduction and in situ diastereoselective alkylations to afford methoxycyclohexadienes bearing new quaternary stereogenic centers. The use of an ester-based auxiliary is a designed improvement over the use of prolinol-derived amides, which are expensive and often very difficult to cleave.

A Direct Synthesis of Highly Substituted π-Rich Aromatic Heterocycles from Oxetanes.

The ubiquitous use of π-rich five-membered heterocycles has driven the development of new methods for their synthesis for more than a century. Here, we disclose a general and reliable reaction manifold for the construction of highly substituted heterocycles through a facile Lewis-acid-catalyzed oxetane rearrangement. Notably, this methodology employs a keto-oxetane motif as a 1,4-dicarbonyl surrogate, which can be synthesized using robust alkylation or alkenylation reactions, and thus obviates the need to access 1,4-dicarbonyl compounds via umpoled starting materials. We harnessed this reactivity to generate a broad range of substituted furans and pyrroles, and extended this methodology to produce benzo-fused versions thereof.

Copper-Catalyzed Amidation of Primary and Secondary Alkyl Boronic Esters.

The oxidative copper-catalyzed cross-coupling of functionalized alkyl boronic esters with primary amides is reported. Through the identification of appropriate diketimine ligands, conditions for efficient coupling of both primary and secondary alkyl boronic esters with diverse primary amides, including acetamide, have been developed.