Chiral diaminophenoxy proligands, H(NN R′ O R ), where R ) t-Bu, H and R′ ) Me, H, have been developed and their respective zinc ethyl complexes, (NN R′ O R )ZnEt, 3a (R ) t-Bu, R′ ) Me), 3b (R ) H, R′ ) Me), 3c (R ) t-Bu, R′ ) H), have been synthesized. The reactivity of 3a with alcohols was explored in detail and compared to a compound reported by Hillmyer, Tolman et al., LZnEt (L ) 2,4di-tert-butyl-6-{[(2′-dimethylaminoethyl)methylamino]-methyl}phenolate). Unlike LZnEt, 3a was inert toward ethanol (as well as methanol, isopropanol, and water). It reacted with phenol and with hydrochloric acid to form (NN Me O tBu )ZnOPh, 4a, and (NN Me O tBu )ZnCl, 5a, respectively. Racemic and enantiopure forms of 4a, (()-4a and (R,R)-4a, were synthesized. The phenoxide complex catalyzed the ring opening polymerization of lactide to atactic poly(lactic acid).

Saturated N-heterocycles are prevalent in pharmaceutical and agrochemical industries, yet remain challenging to catalytically alkylate. Most strategies for C–H activation of these challenging substrates use protected amines or high loadings of precious metal catalysts. We report an early transition-metal system for the broad, robust, and direct alkylation of unprotected amine heterocycles with simple alkenes. Short reaction times are achieved using an in situ generated tantalum catalyst that avoids the use of bases, excess substrate, or additives. In most cases, this catalyst system is selective for the branched reaction product, including examples of products that are generated with excellent diastereoselectivity. Alkene electronic properties can be exploited for substrate-modified regioselectivity to access the alternative linear amine alkylation product with a group 5 catalyst. This method allows for the facile isolation of unprotected N-heterocyclic products, as useful substrates for further reactivity.

This is an in-depth study into the role hemilabile ligands play in tuning stability and reactivity in cationic indium complexes.

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This paper is dedicated to the memory of John Osborn, a close friend and colleague of one of us (BRJ) for over 25 years; John was a person who enjoyed life and made life more enjoyable for others.