Intermolecular Cycloaddition of N-Boranonitrone with Alkenes

Abstract

Ethyl glyoxylate O-tert-butyldimethylsilyloxime (8), on treatment with 2.2 equiv of BF3 x OEt2, generated N-boranonitrone E, which underwent intermolecular cycloaddition with alkenes 18 to afford isoxazolidines 19 in moderate to high yields. The cycloaddition of N-boranonitrone E with most of the alkenes gave 3,5-trans isoxazolidines as the major isomers via a concerted mechanism. However, in the case of 1-methylated cyclic alkenes (18j and 18l), the cycloaddition surprisingly furnished the 3,3a-cis-cycloadducts (19j and 19l) as major isomers. A possible explanation is that the reaction of 1-methylated cyclic alkenes proceeds mainly via a stepwise mechanism. This reaction of terminal alkenes is very useful for synthesis of 1,3-anti aminoalcohol derivatives by reductive cleavage of an N-O bond.

Chemistry and Biology of HPAs: A Family of Ceramide Trafficking Inhibitors

“…Chemler and co-workers [28] described in 2012 an approacht o( 1 S,3R)-syn 1,3-amino alcohol 53 as ap otentialp recursor of (1S,3R)-HPA-12 based on as tereoselective isoxazolidine synthesis (Scheme 16). [30] Scheme13. According to as imilar strategy,T amura's group also described in 2008 as ynthesis of racemic anti-1,3-amino alcohol.…”

“…According to as imilar strategy,T amura's group also described in 2008 as ynthesis of racemic anti-1,3-amino alcohol. [30] Scheme13. Synthesis of (1R,3S)-HPA-12 by Delgado: [17] a) C 11 H 23 COCl, 2N NaOH, 85 %; b) BF 3 ·Et 2 O, EtOH, rt, 85 %; c) i) K-Selectride ,THF, À78 8C; ii)Li-BEt 3 H, 94 %.…”

“…Tamura and co‐workers published in 2015 a synthesis of racemic syn ‐(1 R* ,3 S* )‐HPA‐12 relying on a BF 3 ‐mediated cis ‐selective cycloaddition of O ‐silyloxime with alkenes (Scheme ). According to a similar strategy, Tamura's group also described in 2008 a synthesis of racemic anti ‐1,3‐amino alcohol …”

Diastereoselective synthesis of atropisomeric pyrazolyl pyrrolo[3,4-d]isoxazolidines via pyrazolyl nitrone cycloaddition to facially divergent maleimides: intensive NMR and DFT studies

“…1 Most of the studies have focused on exploring the 1,3-dipole character of nitrones in [3 + 2] dipolar cycloadditions with dipolarophiles to construct functionalized ve-membered heterocycles which are important intermediates in organic synthesis. 2 The dipolarophiles include alkenes, 3 alkynes, 4 allenes 5 and other cumulated double bonds. 6 Isoxazolidines, formed from the [3 + 2] dipolar cycloadditions of nitrones and alkenes, exhibit good biological activities 7 and the possibility of their transformation via ring opening into open-chain derivatives 8 makes them valuable for the synthesis of natural and biologically important compounds such as amino sugars, amino alcohols, alkaloids, b-lactams, and amino acids.…”

Solvent Free, Microwave Assisted Conversion of Aldehydes into Nitriles and Oximes in the Presence of NH2OH·HCl and TiO2

“…Oximes, another important class of aldehyde derivatives, also have useful applications in organic synthesis and in analytical chemistry. These compounds, besides being intermediates for isoxazoline [ 14 ] and N -hydroxylamino nitrile synthesis [ 15 ], also have a potential use in perfumery industry due to their higher stability when compared to their corresponding aldehydes, while retaining a pleasant odour [ 16 ].…”