55702-58-4Relevant articles and documents
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.
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.
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.
