Basker Sundararaju

Transition metal catalyzed nucleophilic allylic substitution: activation of allylic alcohols via π-allylic species.

Modern organic synthesis now requires efficient atom economical synthetic methods operating under greener pathways to achieve C-C and C-heteroatom bond formation. Direct activation of allylic alcohols in the presence of transition metal catalysts leading to electrophilic π-allyl metal intermediates represents such a promising target in the field of nucleophilic allylation reactions. During the last decade, this topic of recognized importance has become an emerging area, and selected transition metals, sometimes associated with alcohol activators, have brought elegant solutions for performing allylic substitution directly from alcohols in a regio, stereo and enantioselective manner.

Cobalt(III)‐Catalyzed Dehydrative [4+2] Annulation of Oxime with Alkyne by CH and NOH Activation

Efficient, scalable cobalt-catalyzed redox-neutral [4+2] annulation of readily available oximes and alkyne is reported. The developed synthetic methodology is widely applicable and tolerates various functional groups including heterocycles. A stable Cp*Co(III) neutral complex is employed as the catalyst for this redox-neutral [4+2] annulation reaction, which progresses smoothly by way of a reversible cyclometallation without any external oxidizing agent, and produces only water as the side product.

A Functional-Group-Tolerant Catalytic trans Hydrogenation of Alkynes

Against the rules: during the hundred years following Sabatiers groundbreaking work on catalytic hydrogenation, syn delivery of the H atoms to the π system of a substrate remained the governing stereochemical rule. An exception has now be found with the use of cationic [Cp*Ru] templates, which accounts for the first practical, functional-group-tolerant, broadly applicable and highly E-selective semihydrogenation method for alkynes.

sp3 C-H bond activation with ruthenium(II) catalysts and C(3)-alkylation of cyclic amines.

A selective C(3)-alkylation via activation/functionalization of sp(3) C-H bond of saturated cyclic amines was promoted by (arene)ruthenium(II) complexes featuring a bidentate phosphino-sulfonate ligand upon reaction with aldehydes. This highly regioselective sustainable transformation takes place via initial dehydrogenation of cyclic amines and hydrogen autotransfer processes.

A general palladium-catalyzed carbonylative sonogashira coupling of aryl triflates.

Trifling with triflates: A new protocol for the carbonylative Sonogashira reactions of aryl triflates (see scheme) that provides a significant extension of this interesting methodology is described.

Ruthenium(IV) Complexes Featuring P,O‐Chelating Ligands: Regioselective Substitution Directly from Allylic Alcohols

Branching out: A new ruthenium(IV) complex (1), containing a P,O-chelating ligand, is an efficient precatalyst for regioselective allylations starting from various allylic alcohol derivatives.

Cobalt Catalyzed C-H and N-H Bond Annulation of Sulfonamide with Terminal and Internal Alkynes.

Chelate assisted cobalt catalyzed C-H and N-H annulation of aryl sulfonamide with terminal and internal alkynes is reported. Very high regioselectivity and excellent functional group tolerance were achieved using oxygen as a co-oxidant. The reaction is scalable under mild conditions.

Cp*CoIII‐Catalyzed C(sp3)−H Bond Amidation of 8‐Methylquinoline

An efficient and external oxidant-free, Cp*Co(III) -catalyzed C(sp(3) )-H bond amidation of 8-methylquinoline, using oxazolone as an efficient amidating agent, is reported for the first time under mild conditions. The reaction is selective and tolerates a variety of functional groups. Based on previous reports and experimental results, the deprotonation pathway proceeds through an external base-assisted concerted metalation and deprotonation process.

C-8-Selective Allylation of Quinoline: A Case Study of β-Hydride vs β-Hydroxy Elimination

An unprecedented C(8)-H bond allylation of quinoline with allyl carbonate and allyl alcohol catalyzed by Cp*Co(III) using a traceless directing group via β-oxygen and β-hydroxy elimination is described. This site-selective allylation reaction proceeds smoothly with various functional group tolerance including quinoxaline and phenanthridine. Under the nonoxidative reaction conditions, the difference in selectivity between Rh(III) and Co(III), which proceeds through β-hydride and β-hydroxy elimination using allyl alcohol, is shown for the first time.

Ruthenium-catalyzed reductive amination of allylic alcohols.

Straighforward access to various saturated amines from allylic alcohols and isostructural mixture can now be achieved in the presence of arene ruthenium catalyst featuring phosphinesulfonate ligand and a hydrogen donor.