55702-58-4Relevant academic research and scientific papers
Azetidine-Borane Complexes: Synthesis, Reactivity, and Stereoselective Functionalization
Andresini, Michael,De Angelis, Sonia,Uricchio, Antonella,Visaggio, Angelica,Romanazzi, Giuseppe,Ciriaco, Fulvio,Corriero, Nicola,Degennaro, Leonardo,Luisi, Renzo
, p. 10221 - 10230 (2018/08/01)
The present study reports, for the first time, the synthesis and structural features of azetidine-borane complexes, as well as their reactivity in lithiation reactions. A temperature-dependent stereoselectivity has been disclosed in the reaction of borane with N-alkyl-2-arylazetidines, allowing for a stereoselective preparation of azetidine-borane complexes 2 and 3. A regioselective hydrogen/lithium permutation, at the benzylic position, was observed in lithiation reactions of complexes possessing a syn relationship, between the ring proton and the BH3 group. In contrast, scarce or no reactivity was noticed in complexes lacking such a stereochemical requirement. The configurational stability of the lithiated intermediates has also been investigated, in order to shed some light on the stereoselectivity of the lithiation/electrophile trapping sequence. Calculations helped in supporting experimental observations, concerning structure and reactivity of these azetidine-borane complexes. Data suggest that the BH3 group could promote the lithiation reaction likely by an electrostatic complex induced proximity effect. Interestingly, a new synthetic strategy for the synthesis of N-alkyl-2,2-disubstituted azetidines has been developed.
2-Arylazetidines as ligands for nicotinic acetylcholine receptors
Degennaro, Leonardo,Zenzola, Marina,Laurino, Annunziatina,Cavalluzzi, Maria Maddalena,Franchini, Carlo,Habtemariam, Solomon,Matucci, Rosanna,Luisi, Renzo,Lentini, Giovanni
, p. 329 - 334 (2017/05/17)
Alternative and complementary procedures were adopted for preparing 2-arylazetidine derivatives in moderate to good yields. Preliminary biological evaluation of 2-arylazetidines as ligands of nicotinic acetylcholine receptors allowed to identify chloro-substituted analogs as the most interesting congeners. The title compounds may be considered as suitable hit compounds for developing new nicotinic acetylcholine receptor ligands that may be safer than the currently available drugs targeting nicotinic acetylcholine receptors. Our described synthetic approaches enable facile access to a large number of diversely decorated azetidines for studying the structure-activity relationships and for refining the toxico-pharmacological profile of these agents.
Synthesis of 3-Aryl-1-aminopropane Derivatives: Lithiation-Borylation-Ring-Opening of Azetidinium Ions
Casoni, Giorgia,Myers, Eddie L.,Aggarwal, Varinder K.
, p. 3241 - 3253 (2016/09/12)
In situ generated 2-phenyl-azetidinium ylides react with boronic esters to form acyclic γ-dimethylamino tertiary boronic esters. The transformation is believed to involve the formation of a zwitterionic boronate, which subsequently undergoes ring-opening 1,2-migration, which is promoted by the relief of ring strain. Owing to the configurational instability of the initially formed ylides, which appear to be in equilibrium with the open-chain carbene form, the reaction is not stereospecific. The C-B bond of the γ-dimethylamino tertiary boronic esters can be transformed into a variety of functional groups (C-OH, C-vinyl, C-H, C-BF3), thus giving a diverse selection of 3-aryl-1-aminopropanes, which represent a privileged motif among drug molecules.
Harnessing the ortho-directing ability of the azetidine ring for the regioselective and exhaustive functionalization of arenes
Zenzola, Marina,Degennaro, Leonardo,Trinchera, Piera,Carroccia, Laura,Giovine, Arianna,Romanazzi, Giuseppe,Mastrorilli, Piero,Rizzi, Rosanna,Pisano, Luisa,Luisi, Renzo
, p. 12190 - 12200 (2015/03/31)
This work demonstrates how the directing ability of the azetidine ring could be useful for regioselective ortho-C-H functionalization of aryl compounds. Robust polar organometallic (lithiated) intermediates are involved in this synthetic strategy. The reagent n-hexyllithium emerged as a safer, yet still effective, basic reagent for the hydrogen/lithium permutation relative to the widely used reagent nBuLi. Two different reaction protocols were discovered for regioselective lithiation at the ortho positions adjacent to the azetidine ring, which served as a toolbox when other competing directing groups were installed on the aromatic ring. The coordinating ability of the azetidine nitrogen atom, as well as the involvement of dynamic phenomena related to the preferential conformations of 2-arylazetidine derivatives, were recognized to be responsible for the observed reactivity and regioselectivity. A site-selective functionalization of the aromatic ring was achieved for aryl azetidines with either coordinatively competent groups (e.g. methoxy) or inductively electron-withdrawing substituents (e.g. chlorine and fluorine). By fine-tuning the reaction conditions, regioselective introduction of several substituents on the aromatic ring could be realized. Several substitution patterns were accomplished, which included 1,2,3-trisubstitution, 1,2,3,4-tetrasubstitution, and 1,2,3,4,5-pentasubstitution, up to the exhaustive substitution of the aromatic ring.
Regioselective functionalization of 2-arylazetidines: Evaluating the ortho-directing ability of the azetidinyl ring and the α-directing ability of the N-substituent
Degennaro, Leonardo,Zenzola, Marina,Trinchera, Piera,Carroccia, Laura,Giovine, Arianna,Romanazzi, Giuseppe,Falcicchio, Aurelia,Luisi, Renzo
supporting information, p. 1698 - 1700 (2014/02/14)
The regioselective lithiation-functionalization of 2-arylazetidines has been explored. The nature of the N-substituent is mainly responsible for a regioselectivity switch. ortho-Lithiation occurred, using hexyllithium as a greener base, in N-alkylazetidines, while α-benzylic lithiation has been observed with N-Boc azetidines.
Photophysical and photochemical behavior of intramolecular-styrene-amine exciplexes
Lewis, Frederick D.,Dasharatha Reddy,Schneider, Siegfried,Ga, Michael
, p. 3498 - 3506 (2007/10/02)
The photophysical and photochemical behavior of a series of secondary and tertiary ω-(β-styryl)aminoalkanes with one to five methylenes separating the styryl and amino groups has been investigated and compared to the intermolecular reactions of 1-phenylpropene with secondary and tertiary amines. The tertiary styrylamines form fluorescent intramolecular exciplexes, but fail to undergo intramolecular addition reactions. Both the rate constant for exciplex formation and the stability of the exciplex are dependent upon the length of the polymethylene chain connecting the chromophores. The failure of the tertiary amine exciplexes to undergo intramolecular addition is attributed to an unfavorable exciplex geometry for α-C-H transfer to the styrene double bond. While the secondary styrylamines do not form fluorescent exciplexes, the dependence of the styrene singlet lifetime upon the polymethylene chain length is similar to that for the tertiary styrylamines. Intramolecular N-H addition to the styrene double bond results in the formation of two regioisomeric (α-phenyl and α-benzyl) cyclic amines of different ring size. The regioisomer of larger ring size is favored except in the case in which four methylenes separate the chromophores. The effects of polymethylene chain length, solvent polarity, temperature, and the bulk of the N-alkyl group upon product yields and ratios are discussed in terms of a mechanism involving singlet exciplex and biradical intermediates.
