Highly enantio-stereoselective Ni-catalyzed reductive cyclization to cyclopentanes with chiral quaternary centres of trisubstituted allylic siloxanes

The construction of chiral quaternary carbon stereocenters is a significant challenge in asymmetric synthesis.Catalytic synthesis of these structures with trisubstituted allylic alcohols is highly important. However, most ofthe reported methodologies required noble transition-metals. Herein we reported the first highly asymmetricstereoselective synthesis of cyclopentanes bearing chiral quaternary carbon stereocenters of trisubstituted allylicsiloxanes by reductive cyclization of all carbon 1,6-alkynones with the non-noble nickel catalysis of Ni(cod)2 withP-chiral monophosphine ligand (S)-BIDIME. Various multi-substituted functionalized cyclopentanes were obtained in high yields (up to 96%), excellent enantioselectivities (up to >99% ee) and perfect stereoselectivities(>99:1 E/Z). Thirty-two examples were successfully established for this method. Clarified mechanism studieswere investigated first time by React-IR and DFT calculations to understand and explain the ligand-control ofexcellent enantio-stereoselectivity. Gram-scale reaction and control experiments were carried out. A new reactiondesign was proposed for further application of this type of catalysis.

Divergent Syntheses of Pyridoacridine Alkaloids via Palladium-Catalyzed Reductive Cyclization with Nitro-Biarenes

Main observation and conclusion A divergent and novel protocol for the preparation of both pyrido[2,3,4-kl]acridine and pyrido[4,3,2-kl]acridine alkaloids was developed.This method featured the remote palladium-catalyzed reductive cyclization with Mo(CO)_(6) as reductant.A wide range of substrates including three types of nitro arenes were tolerated and afforded corresponding products in good to excellent yields.

Phosphinic Acid/Nal Mediated Reductive Cyclization Approach for Accessing the L-1-Deoxynojirimycin Using a Two-Component Three-Centered (2C3C) Ugi Type Reaction

A catalytic two-component three-centered(2C3C)Ugi-type reaction was developed for the synthesis of L-1-deoxynojirimycin(DNJ)isomers using a chiron approach.This new and quite mild catalytic system,comprised of phenylphosphinic acid/Nal,was used to synthesize both the L-allo-DNJ and L-altro-DNJ in high yield.

Low-valent titanium induced reductive cyclization of nitro compounds and aliphatic ketones:facile synthesis of 3,4-dihydro-(2H) -1,2,4-benzothiadiazine-1,1-dioxides

The intermolecular reductive cyclization of o-nitrobenzene-sulfonamides with aliphatic ketones induced by TiCl4/Sm system was studied and a series of 3, 3-disubstituted-3,4-dihydro(2H)-1,2, 4-benzothiadiazine-1,1-dioxides were synthesized in moderate to high yields under mild and neutral conditions.

One pot synthesis of bis-silicon-bridged stilbene derivatives

Bis-silicon-bridged stilbene derivatives were synthesized in a modified procedure that combined the preparation of bis[2- （silyl）phenyl]acetylene and its intramolecular reductive cyclization in one pot. The results indicated that the one pot approach produced target products in a comparable yield to that of the two-step method reported previously.

An Efficient Preparation of 2, 3-Disubstituted Indole Derivatives Induced by Low-valent Titanium

An efficient synthesis of 2, 3-disubstituted indole derivatives through low-valent titanium induced reductive cyclization of acylamido carbonyl compounds is described.

A Novel Synthesis of 3,4-DihydrO-(2H)-1,2,4-Benzothiadiaizine-1,1-Dioxides Promoted by Samarium Diiodide

Dihydro-(2H)-1 .2.4-benzothiadizine-1. 1-dioixdes were prepared in good yields via reductive cyclization of o-nitrobenzenesulfonamidcs with aldchydes promoted by Sml2 under mild and neutral condition.

Reductive Coupling Cyclization of 1,1-Dicyanoalkenes Promoted by Sm^0/cat. HgCl_2 System

The intermolecular reductive coupling cyclization reactions of 1,1-dicyanoalkenes promoted by Sm-0/cat. HgCl2 were studied. A possible reaction mechanism was proposed.

Synthesis of 2,5-disubstitued benzimidazole using SnCl_2-catalyzed reduction system at room temperature

Stannous chloride dihydrate is used as an efficient catalyst in reductive cyclization of 2-nitro-5- substituted aniline Schiff base leading to stable 2,5-disubstitued benzimidazole derivatives in excellent yields with good purity. It provides a novel method of synthesis of 2,5-disubstitued benzimidazole under reductive system at room temperature.

Synthesis of 2-Aminoindole Derivatives with Hantzsch Ester Catalyzed by Pd/C

Catalytic hydrogenation of 2-cyano-2-（2-nitrophenyl）acetates bearing an electron withdrawing substituent to the nitrile, using Hantzsch ester catalyzed by Pd/C, affords 2-aminoindoles in good to excellent yields.