ChemInform Abstract: Reductive Cleavage of 4,5‐Cycloalkanoisoxazolines.

Abstract

Reductive cleavage of the anellated isoxazolines (I) with Raney‐nickel in the presence of acids gives the dihydroxy ketones (II) and/or its dehydration products (III).

Unusual transformations of 2-isoxazolines

“…2,3,15,51 It is noteworthy that the reduction of the isoxazoline 83c with sodium tetrahydroborate results in the formation of the carbonylgroup reduction product, 86. Upon reductive cleavage (Raney Ni, AlCl 3 , MeOH ± H 2 O), 5-pyridylisoxazolines 83a-c and 5-phenyl(phenoxymethyl)isoxazolines 83d,e give the b-hydroxy ketones 87, which is typical of isoxazoline cleavage by reagents of this type.…”

“…Upon reductive cleavage (Raney Ni, AlCl 3 , MeOH ± H 2 O), 5-pyridylisoxazolines 83a-c and 5-phenyl(phenoxymethyl)isoxazolines 83d,e give the b-hydroxy ketones 87, which is typical of isoxazoline cleavage by reagents of this type. 1,3 The formation of different products in the reaction with nucleophilic agents from the 5-pyridylisoxazolines 83a ± c and from the 5-phenylisoxazolines 83d,e points to the involvement of the substituent at C(5). In the case of the derivatives 83a ± c, the products of the cyclodegradation of the isoxazoline fragment form, and the ketone-nitrile 1,3-cycloreversion of 5-(4-pyridyl)-2-isoxazolines observed is similar to the cycloreversion of 5-acyland 5-nitro-2-isoxazolines and seems to proceed in accordance with Scheme 9:…”

“…7, 11 ± 13, 17 ± 19 Alkylation of the anions 2b and 2e by electrophiles is used for the modification of the heterocycle and subsequent generation of a functionalised acyclic compound from the isoxazoline derivative. 2,3 Analysis of a great number of publications has revealed that an unambiguous result can hardly be achieved in reactions with bases due to a number of factors intervening. The main factors are the structure of the substrate and the nature of the base interacting with it.…”