Danyu Gu

1 Introduction Transition-metal-catalyzed carbene transfer reactions represent a versatile strategy for chemical bond formation in modern organic synthesis [1-5]. Historically, diazo compounds have served as the dominant carbene precursors [6-9]. However, their inherent instability and explosive nature raise significant safety concerns and limit practical application, particularly in scalable scenarios [10, 11].

Ketones are ubiquitous in organic synthesis. However, the general method to convert widely available carboxylic acids, unactivated esters, and amides into ketones remains elusive. Herein, we describe the Ti-catalyzed modular ketone synthesis from carboxylic derivatives and easily accessed gem-dihaloalkanes. Notably, this protocol could achieve the direct catalytic olefination of carboxylic acids.