Asymmetric multicomponent reactions (AMCRs): the new frontier

Asymmetric Multicomponent Domino Reactions and Highly Enantioselective Conjugated Addition of Thiols to α,β-Unsaturated Aldehydes

An organocatalytic asymmetric multicomponent domino and a conjugated addition reaction to alpha,beta-unsaturated aldehydes are presented. The development is based, first, on an organocatalyzed highly enantioselective nucleophilic thiol addition to the beta-carbon atom in the iminium ion intermediate, followed by an electrophilic amination of the alpha-carbon atom to the enamine intermediate. The multicomponent reactions proceed to give enantiopure amino-thiols in moderate to good yields. Furthermore, the organocatalyzed thiol addition to alpha,beta-unsaturated aldehydes takes place in good yields and excellent enantioselectivities.

Domino Coupling Relay Approach to Polycyclic Pyrrole-2-carboxylates

CuBr2-catalyzed three-component coupling of N-benzylallylamine, ethyl glyoxalate, and terminal alkynes afforded glycine-tethered 1,6-enynes, which were further transformed into polycyclic pyrrole-2-carboxylates via novel cycloisomerization/Diels-Alder cycloaddition/dehydrogenation sequence under iridium-catalyzed conditions.

Highly Regioselective, Catalytic Asymmetric Reductive Coupling of 1,3-Enynes and Ketones

[reaction: see text] Highly regioselective, catalytic asymmetric reductive coupling reactions of 1,3-enynes and ketones have been achieved using catalytic amounts of Ni(cod)(2) and a P-chiral, monodentate ferrocenyl phosphine ligand. These couplings represent the first examples of catalytic, intermolecular reductive coupling of alkynes and ketones, enantioselective or otherwise, and afford synthetically useful 1,3-dienes possessing a quaternary carbinol stereogenic center in up to 70% ee.

Wanted: new multicomponent reactions for generating libraries of polycyclic natural products

The amalgamation of two of combinatorial chemistry's most attractive concepts--natural product libraries and multicomponent reactions (MCRs)--should provide a powerful tactic for generating libraries of bioactive compounds. Yet, despite many recent advances in this area, only a few MCRs can deliver functionalized products whose structures closely resemble that of complex polycyclic natural products. A large proportion of recently developed MCRs are based on [4+2] or [3+2] cycloadditions, and isocyanide-based processes. Because of substrate limitations, however, they are not always ideally suitable for applications in diversity-oriented synthesis of natural product-like compounds. A promising area awaiting further development is the use of transition metal-catalyzed cascade reactions.

One-pot multi-step synthesis: a challenge spawning innovation

Creating one-pot synthetic routes is a challenge that is already spawning new chemistry, enzymes, materials, and mechanistic insight. Through one-pot reactions, the chemical products that add value to our lives can be produced with less waste and greater economic benefits. Within this Emerging Area, we describe models for designing one-pot reactions as well as advanced catalysts created to facilitate their realization.