The development of a new efficient synthetic method of nitrogen containing compounds is extensively studied because there are many nitrogen containing compounds such as amino acids, alkaloids, and β-lactams having biological activities and functionalized materials for organic electronics or photonics. During the investigation of Mannich-type reactions of α,β-unsaturated imines with ketene silyl acetals, we found that 1,4-and 1,2-double nucleophilic addition reactions proceeded to give doubly alkylated products in good yields. Various nucleophiles can be also used such as allyltins, ketene silyl thio acetals, trimethylsilyl cyanide, thiols, and hydrogen azide. Using 1,4-and 1,2-double nucleophilic addition reactions with ketene silyl acetal and trimethylsilyl cyanide as a key reaction, an imidazole glycerol phosphate dehydratase inhibitor(IGPDI) possessing a monopyrrole aldehyde moiety is synthesized. 2-Iminopyridine synthesis is found in the conjugate addition of cyanoacetate derivatives to alkynyl imines. Stereodivergent synthesis of both cis-and trans-β-lactams is presented using the following three reactions: Iminocyclobutenone formation, chemoselective reduction of imino groups, and thermal rearrangement of aminocyclobutenones as crucial steps, in which the starting materials, iminocyclobutenones, were readily synthesized using conjugate addition reactions of alkynyl imines with ketene silyl acetals in good yields.
Enantioselective bond formation reaction is of great interest to medicinal or material science. In order to develop the synthetic methodology for these compounds, we designed heteroarenesulfonyl groups as an activating group for imines and a protecting group for amines. The heteroarenesulfonyl group was shown to be an efficient protective group, which has notable properties of high chiral inducibility and activation of the imino group toward the addition of several nucleophiles. Furthermore, we designed N-(heteroarenesulfonyl)prolinamides as novel organocatalysts. Enantioselective aldol reaction of acetone or acetaldehyde with various isatin derivatives using N-(2-thiophenesulfonyl)prolinamide afforded convolutamydine derivatives with high enantioselectivity.
This article describes several hydrogen transfer oxidation by an iridium amide catalyst. Oxidative lactonization, oxidative dimerization, and Oppenauer type-oxidation proceed by a novel iridium aminoalkoxide complex in ketonic solvent. Asymmetric oxidative lactonization and oxidative desymmetrization developed in this study were found to be useful for bioactive compound synthesis.
This article focuses on the development of an aromatic amination reaction using CuI and CsOAc and its application to total syntheses of nitrogen-containing cyclic natural products. The reaction conditions present several unprecedented features that have not been observed in conventional palladium-catalyzed systems, including high functional group compatibility (e.g., N-alloc-and sp2-Br are retained) and applicability for highly hindered substrates. The utility of this reaction has been fully demonstrated through total syntheses of duocarmycins, yatakemycin, and PDE-II.
Many examples of solid-state photoreactions using chiral crystals composed of achiral materials and leading to optically active products have been successfully demonstrated and recognized as absolute asymmetric synthesis. Recently, we have discovered a new methodology for asymmetric synthesis using the molecular chirality in crystal as a source of homochirality in fluid media. The chirality can be effectively transferred to optically active products by asymmetric reactions involving nucleophilic reactions and an intermolecular photochemical reaction, and which had so far not been achieved in solid state reactions.
We have been exploring new organic reactions and new class of organic functional materials based on the concept of “modular synthesis.” This manuscript presents our recent progress on the synthesis of a series of fused carbo- and heteroaromatic compounds by means of the development of intramolecular cyclization reaction. Utility of these new materials in organic electronic devices, such as organic light-emitting diodes (OLEDs) and organic solar cells, is also demonstrated.
Photochemical reactions provide powerful methods for synthesizing complex molecules. They have attracted considerable attention due to their unique reaction pathways through the excited states. This mini-review surveys some recent literatures, which show the potential and capacity of photochemical reactions in natural product total syntheses.
Recently, total synthesis of Palau’amine and its analogues, polycyclic dimeric pyroole-imidazole alkaloid, has been accomplished by Phil, S. Baran and co-workers. These alkaloids contain closely functionalized polycyclic rings and structurally complicated aminal moieties. Generally, the regio- and stereo-selective constructions of aminal moieties are difficult to control, because of its stability and reactivity. In this review, it will be focused on the strategy for the construction of aminal moieties in a later stage of the synthesis, and discussed about his novel and artful synthetic plan making a new wave continually.