Strained azetidinium ylides: new reagents for epoxidation

Abstract

Azetidinium ylides effected facile epoxidation of various carbonyl compounds furnishing tri or tetrasubstituted epoxides that were unattainable via classical ammonium ylide chemistry; the produced trisubstituted oxiranes gave rise to a remarkable cascade of reactions leading to some original pyrrolidin-3-ones.

Complexation Phenomena and Dynamics at Work in the Lithiation Reactions of Small‐Ring Heterocycles: Regio‐ and Stereoselectivity

“…[65] The lithiation of 2-arylazetidines has been explored only recently emphasizing the role of the N-substituent on the regioselectivity of the lithiation reaction. [65] The lithiation of 2-arylazetidines has been explored only recently emphasizing the role of the N-substituent on the regioselectivity of the lithiation reaction.…”

Ring Expansion of 2‐(1‐Hydroxyalkyl)azetidines to 4‐(2‐Chloroethyl)oxazolidinones

“…Usual workup gave a crude oil, which was a mixture of 27 and the corresponding imine. The residue was purified by flash chromatography (PE/AcOEt, 9:1; R f = 0.3) to give compound 27 as an oil (300 mg, 55 % Ketone 28: BuLi (1.6 m in hexane, 2.85 mL, 4.57 mmol) was added dropwise to a solution of 26 [13] (425 mg, 2.28 mmol) in THF (20 mL) at 0°C. The reaction mixture was stirred at 0°C for 2 h and hydrolyzed by the addition of a saturated aqueous solution of NH 4 Cl (15 mL).…”

“…[17] β-Amino Alcohol 21: Following the procedure described above for 20 by using tert-butyl 2-bromopropionate [18] as alkylating agent, compound 21 was obtained as an oil (8.3 g, 90 %) after purification by flash chromatography (PE/AcOEt, 8:2; R f = 0.6). 1 Ketone 27: MeLi (1.6 m in diethyl ether, 3.36 mL, 5.37 mmol) was added dropwise to a solution of 26 [13] (500 mg, 2.69 mmol) in toluene (15 mL) at 0°C. The reaction mixture was stirred at 0°C for 1 h and hydrolyzed by the addition of a saturated aqueous solution of NH 4 Cl (15 mL).…”

2‐Cyanoazetidines and Azetidinium Ions: Scaffolds for Molecular Diversity

“…The produced azetidinium ylide is highly nucleophilic and displays rich reactivity. Alternatively, these ylides can react intermolecularly with carbonyl compounds [43] [aldehydes or ketones; Scheme 22, Eqs. (1) and (2)] through a [2,3] sigmatropic rearrangement, which allows easy access to enantiopure azetidines with quaternary centers.…”

“…[42] In these reactions, perfect N-to-C chirality transfer is observed. Alternatively, these ylides can react intermolecularly with carbonyl compounds [43] [aldehydes or ketones; Scheme 22, Eqs. (3) and (4)] or Michael acceptors [44] [Scheme 22, Eq.…”