Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates, and reagents, even when targeting similar compounds. This approach slows down discovery and limits available chemical space. Introduced herein is a practical and versatile diazocompound and its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. The redox‐active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect allowed the asymmetric cyclopropanation of various olefins, including unfunctionalized aliphatic alkenes, that enables the three‐step total synthesis of (−)‐dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally differentiated diazocompounds are viable and advantageous equivalents of single‐carbon chirons.

The alkylidyne complex (C5Me5)­Ta­(CPh)­(PMe3)2Cl (1) was first reported by Schrock in 1978, but little if any follow-up work on 1 or other group 5 metal alkylidynes has been reported. This work discloses two avenues of reactivity of 1. Treatment of 1 with 3-hexyne resulted in the formation of a tantalacyclobutadiene. Abstraction of chloride from 1 led to a mixture of products that included isomers of [(C5Me5)­Ta­(CHPh)­(CH2PMe2)­(PMe3)]+ (4), in which a C–H bond of a PMe3 ligand was added across the TaC bond. The C–H activation was found to be reversible, and the equilibrium mixture functioned as an equivalent of a cationic Ta alkylidyne in reaction with 3-hexyne, producing a cationic tantalacyclobutadiene (6). Compounds 4 and 6 were structurally characterized in the solid state by XRD methods, with 6 being the first structurally characterized metallacyclobutadiene in group 5.

A zwitterionic construction has been synthesized that covalently links a trialkylsilylium cation and a weakly coordinating carborane anion in one neutral molecule (see X‐ray structure; Si green, C gray, B orange, Cl red). The silylium character of this molecule is supported by DFT calculations (see LUMO), 29Si CP/MAS NMR spectroscopy, and reactivity.

A method for C-alkylation of [HCB(11)Cl(11)](-) anions using potassium tert-butoxide and alkyl iodides in tert-butanol is presented. Trimethylammonium salts of the corresponding C-alkylated derivatives are easily isolated and obtained in good yields.

Ap riority patent application has been filed (1850940-6), where A.M.,M .M-M.,M .C.a nd E.M.-C.a re listed as inventors.