170304-99-1Relevant academic research and scientific papers
Palladium-Catalyzed Regioselective and Stereospecific Ring-Opening Suzuki-Miyaura Arylative Cross-Coupling of 2-Arylazetidines with Arylboronic Acids
Takeda, Youhei,Toyoda, Kazuya,Sameera,Tohnai, Norimitsu,Minakata, Satoshi
supporting information, p. 2796 - 2805 (2021/04/15)
We have developed a palladium-catalyzed regioselective and enantiospecific ring-opening Suzuki–Miyaura arylative cross-coupling of N-tosyl-2-arylazetidines to give enantioenriched 3,3-diarylpropylamines. This reaction represents an example of transition-metal-catalyzed ring-opening cross-coupling using azetidines as a non-classical alkyl electrophile. Density functional theory rationalized the mechanism of the full catalytic cycle, which consists of the selectivity-determining ring opening of the azetidine, reaction with water, rate-determining transmetalation, and reductive elimination. Transition states of the selectivity-determining ring-opening step were systematically determined by the multi-component artificial force induced reaction (MC-AFIR) method to explain the regioselectivity of the reaction. (Figure presented.).
Branched Amine Synthesis via Aziridine or Azetidine Opening with Organotrifluoroborates by Cooperative Br?nsted/Lewis Acid Catalysis: An Acid-Dependent Divergent Mechanism
Nguyen, Truong N.,May, Jeremy A.
, p. 3618 - 3621 (2018/06/26)
A practical catalytic method to synthesize β,β- and γ,γ-substituted amines by opening aziridines and azetidines, respectively, using alkenyl, alkynyl, or aryl/heteroaryl trifluoroborate salts is described. This reaction features simple open-flask reaction conditions, the use of transition-metal-free catalysis, complete regioselectivity, and high diastereoselectivity. Preliminary mechanistic studies suggest that carbocation formation is disfavored. Stereoretentive addition is favored with Br?nsted acid present, while stereoinversion is favored in its absence, indicating divergent mechanisms.
A highly active and air-stable ruthenium complex for the ambient temperature anti-markovnikov reductive hydration of terminal alkynes
Zeng, Mingshuo,Li, Le,Herzon, Seth B.
supporting information, p. 7058 - 7067 (2014/06/09)
The conversion of terminal alkynes to functionalized products by the direct addition of heteroatom-based nucleophiles is an important aim in catalysis. We report the design, synthesis, and mechanistic studies of the half-sandwich ruthenium complex 12, which is a highly active catalyst for the anti-Markovnikov reductive hydration of alkynes. The key design element of 12 involves a tridentate nitrogen-based ligand that contains a hemilabile 3-(dimethylamino) propyl substituent. Under neutral conditions, the dimethylamino substituent coordinates to the ruthenium center to generate an air-stable, 18-electron, κ3-complex. Mechanistic studies show that the dimethylamino substituent is partially dissociated from the ruthenium center (by protonation) in the reaction media, thereby generating a vacant coordination site for catalysis. These studies also show that this substituent increases hydrogenation activity by promoting activation of the reductant. At least three catalytic cycles, involving the decarboxylation of formic acid, hydration of the alkyne, and hydrogenation of the intermediate aldehyde, operate concurrently in reactions mediated by 12. A wide array of terminal alkynes are efficiently processed to linear alcohols using as little as 2 mol % of 12 at ambient temperature, and the complex 12 is stable for at least two weeks under air. The studies outlined herein establish 12 as the most active and practical catalyst for anti-Markovnikov reductive hydration discovered to date, define the structural parameters of 12 underlying its activity and stability, and delineate design strategies for synthesis of other multifunctional catalysts.
Temporal separation of catalytic activities allows anti-Markovnikov reductive functionalization of terminal alkynes
Li, Le,Herzon, Seth B.
, p. 22 - 27 (2014/01/17)
There is currently great interest in the development of multistep catalytic processes in which one or several catalysts act sequentially to rapidly build complex molecular structures. Many enzymes - often the inspiration for new synthetic transformations - are capable of processing a single substrate through a chain of discrete, mechanistically distinct catalytic steps. Here, we describe an approach to emulate the efficiency of these natural reaction cascades within a synthetic catalyst by the temporal separation of catalytic activities. In this approach, a single catalyst exhibits multiple catalytic activities sequentially, allowing for the efficient processing of a substrate through a cascade pathway. Application of this design strategy has led to the development of a method to effect the anti-Markovnikov (linear-selective) reductive functionalization of terminal alkynes. The strategy of temporal separation may facilitate the development of other efficient synthetic reaction cascades.
A convenient synthetic route to 2-aryl-N-tosylazetidines and their ZnX2 (X = I, OTf) mediated regioselective nucleophilic ring opening reactions: synthesis of γ-iodoamines and tetrahydropyrimidines
Ghorai, Manas K.,Das, Kalpataru,Kumar, Amit,Das, Animesh
, p. 5393 - 5397 (2007/10/03)
A general and convenient synthetic route to various 2-aryl-N-tosylazetidines has been described. Their ZnX2 (X = I, OTf) mediated nucleophilic ring opening with halides and [4+2] cycloaddition reactions with various nitriles have been achieved
Studies of Regio- and Stereoselectivity in Some Nucleophilic Ring Opening Reactions of N-Tosyl-3-phenyl-2-aziridinemethanols and Derivatives
Tanner, David,Gautun, Odd R.
, p. 8279 - 8288 (2007/10/02)
A study has been made of the regio- and stereoselectivity of the ring opening reactions of the 3-aryl substituted aziridines 1 and 2.The regiochemical outcome is apparently decided by a balance of electronic activation at C-3 by the phenyl group and the c
