174310-75-9

Upstream product

• 24424-99-5 di-tert-butyl dicarbonate 
• 188488-64-4 4-[(t-butoxycarbonyl)-amino]-4-phenylbutanol mesylate 
• 154874-86-9 tert-butyl benzyl(3-chloropropyl)carbamate 
• 7332-01-6 1-(4-azidobutyl)benzene 
• 98014-76-7 3-[N-benzyl-N-(tert-butoxycarbonyl)amino]propan-1-ol 
• 4720-29-0 3-(benzylamino)propan-1-ol 
• 5433-11-4 N-Benzyliden-3-hydroxy-1-propanamin 
• 98014-77-8 3-(N-benzyl-N-tert-butoxycarbonylamino)propanal 
• 100-52-7 benzaldehyde 
• 700-91-4 2-phenyl-1-pyrroline 
• 108-86-1 bromobenzene 
• 86953-79-9 tert-butyl pyrrolidine-1-carboxylate 
• 316813-33-9 Allyl-((E)-(R)-2-benzenesulfonyl-1-phenyl-but-2-enyl)-amine 
• 316813-29-3 (E)-(R)-2-Benzenesulfonyl-1-phenyl-but-2-enylamine 

Downstream Products

• 1006-64-0 (S)-2-phenylpyrrolidine 

Relevant academic research and scientific papers

Ligand-controlled β-selective C(sp3)-H arylation of N-Boc-piperidines

We report a general palladium-catalyzed β-arylation of Boc-piperidines, which yields a variety of valuable 3-arylpiperidines in a simple and direct manner. The β- vs. α-arylation selectivity was controlled by the ligand, with flexible biarylphosphines providing mainly the desired β-arylated products whereas more rigid biarylphosphines mainly furnished the more classical α-arylated products. The computed reaction mechanism (DFT), studied from the common α-palladated intermediate, indicated that the reductive elimination steps leading to the α- and β-arylated products are selectivity-determining. Moreover, the experimental trend obtained with different ligands was well reproduced by the calculations.

CINCHONINE-DERIVED CATALYSTS AND METHODS OF USING SAME

The present invention includes certain conchinine-derived phase-transfer catalysts of formula (I), compositions comprising the same, and methods of promoting asymmetric addition reactions using the same.

Enantioselective intramolecular C-H amination of aliphatic azides by dual ruthenium and phosphine catalysis

The catalytic enantioselective intramolecular C(sp3)-H amination of aliphatic azides represents an efficient method for constructing chiral saturated cyclic amines which constitute a prominent structural motif in bioactive compounds. We report a dual catalytic system involving a chiral-at-metal bis(pyridyl-NHC) ruthenium complex and tris(4-fluorophenyl)phosphine (both 1 mol%), which facilitates the cyclization of aliphatic azides to chiral α-aryl pyrrolidines with enantioselectivities of up to 99% ee, including a pyrrolidine which can be converted to the anti-tumor alkaloid (R)-(+)-crispine. Mechanistically, the phosphine activates the organic azide to form an intermediate iminophosphorane and transfers the nitrene unit to the ruthenium providing an imido ruthenium intermediate which engages in the highly stereocontrolled C-H amination. This dual catalysis combines ruthenium catalysis with the Staudinger reaction and provides a novel strategy for catalyzing enantioselective C-H aminations of unactivated aliphatic azides.

Enantioselective Radical Cyclization for Construction of 5-Membered Ring Structures by Metalloradical C-H Alkylation

Radical cyclization represents a powerful strategy for construction of ring structures. Traditional radical cyclization, which is based on radical addition as the key step, necessitates the use of unsaturated substrates. Guided by the concept of metalloradical catalysis, a different mode of radical cyclization that can employ saturated C-H substrates is demonstrated through the development of a Co(II)-based system for catalytic activation of aliphatic diazo compounds for enantioselective radical alkylation of various C(sp3)-H bonds. It allows for efficient construction of chiral pyrrolidines and other valuable 5-membered cyclic compounds. This alternative strategy of radical cyclization provides a new retrosynthetic paradigm to prepare five-membered cyclic molecules from readily available open-chain aldehydes through the union of C-H and C=O elements for C-C bond formation.

Cobalt-Porphyrin-Catalysed Intramolecular Ring-Closing C?H Amination of Aliphatic Azides: A Nitrene-Radical Approach to Saturated Heterocycles

Cobalt-porphyrin-catalysed intramolecular ring-closing C?H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines, imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air- and moisture-stable catalyst. Kinetic studies of the reaction in combination with DFT calculations reveal a metallo-radical-type mechanism involving rate-limiting azide activation to form the key cobalt(III)-nitrene radical intermediate. A subsequent low barrier intramolecular hydrogen-atom transfer from a benzylic C?H bond to the nitrene-radical intermediate followed by a radical rebound step leads to formation of the desired N-heterocyclic ring products. Kinetic isotope competition experiments are in agreement with a radical-type C?H bond-activation step (intramolecular KIE=7), which occurs after the rate-limiting azide activation step. The use of di-tert-butyldicarbonate (Boc2O) significantly enhances the reaction rate by preventing competitive binding of the formed amine product. Under these conditions, the reaction shows clean first-order kinetics in both the [catalyst] and the [azide substrate], and is zero-order in [Boc2O]. Modest enantioselectivities (29–46 % ee in the temperature range of 100–80 °C) could be achieved in the ring closure of (4-azidobutyl)benzene using a new chiral cobalt-porphyrin catalyst equipped with four (1S)-(?)-camphanic-ester groups.

Asymmetric lithiation trapping of N -boc heterocycles at temperatures above -78°C

The asymmetric lithiation trapping of N-Boc heterocycles using s-BuLi/chiral diamines at temperatures up to -20°C is reported. Depending on the N-Boc heterocycle, lithiation is accomplished using s-BuLi and (-)-sparteine or the (+)-sparteine surrogate in the temperature range -50 to -20°C for short reaction times (2-20 min). Subsequent electrophilic trapping or transmetalation-Negishi coupling delivered functionalized N-Boc heterocycles in 47-95% yield and 77:23-93:7 er. With N-Boc pyrrolidine, trapped products can be generated in ～90:10 er even at -20°C.

Highly effective asymmetric hydrogenation of cyclic N -alkyl imines with chiral cationic Ru-MsDPEN catalysts

A range of cyclic N-alkyl imines were efficiently hydrogenated by using a chiral cationic Ru(η6-cymene)(MsDPEN)(BArF) complex (MsDPEN = N-(methanesulfonyl)-1,2-diphenylethylenediamine) in high yields and up to 98% ee. A one-pot synthesis of chiral 2-phenylpyrrolidine via reductive amination was also developed.

Enantioselective, palladium-catalyzed α-arylation of N-Boc pyrrolidine: In situ react IR spectroscopic monitoring, scope, and synthetic applications

A comprehensive study of the enantioselective Pd-catalyzed α-arylation of N-Boc pyrrolidine has been carried out. The protocol involves deprotonation of N-Boc pyrrolidine using s-BuLi/(-)-sparteine in TBME or Et2O at -78 °C, transmetalation with ZnCl2 and Negishi coupling using Pd(OAc)2, t-Bu3P-HBF4 and the aryl bromide. This paper reports several new features including in situ React IR spectroscopic monitoring of the process; use of (-)-sparteine and the (+)-sparteine surrogate to access products with opposite configuration; development of a catalytic asymmetric lithiation-Negishi coupling reaction; extension to a wide range of heteroaromatic bromides; total synthesis of (R)-crispine A, (S)-nicotine and (S)-SIB-1508Y via short synthetic routes; and examples of α-vinylation of N-Boc pyrrolidine using vinyl bromides exemplified by the total synthesis of naturally occurring (+)-maackiamine (thus establishing its configuration as (R)). In this way, the full scope and limitations of the methodology are delineated.

Enantioselective syntheses of 2-substituted pyrrolidines from allylamines by domino hydroformylation-condensation: Short syntheses of (S)-nicotine and the alkaloid 225C

Short routes to chiral 2-substituted pyrrolidines based on rhodium-catalyzed hydroformylations of allylamines and their N-alkyl and N-acyl derivatives, which were prepared by asymmetric allylic substitutions, are described. The outcome of the hydroformyla

Enantioselective, palladium-catalyzed α-arylation of N-Boc-pyrrolidine

This communication discloses the first instance of the enantioselective Pd-catalyzed α-arylation of N-Boc-pyrrolidine. The methodology relies on Beak's sparteine-mediated, enantioselective deprotonation of N-Boc-pyrrolidine to form the 2-pyrrolidinolithium specices in high enantiomeric ratio (er). Transmetalation of this intermediate with zinc chloride generates the stereochemically rigid, 2-pyrrolidinozinc reagent, which was readily coupled to a variety of functionalized aryl halides at room temperature using a catalyst generated from Pd(OAc)2 and PtBu3-HBF4. A diverse array of 2-aryl-N-Boc-pyrrolidines was synthesized using this methodology, providing adducts consistently in a 96:4 er. A survey of the stoichiometry revealed that as little as 0.3 equiv of zinc could be used in the coupling reaction, and the 2-pyrrolidinozinc reagent was found to exhibit stereochemical stability up to 60 °C. The method allows for the most convergent and reliable preparation of a broad range of functionalized 2-aryl-N-Boc-pyrrolidines in high enantioselectivity, which is highlighted in this report by the enantioselective synthesis of (R)-nicotine. Copyright