Beckmann cleavage

The only preparation reported for 7-cyanoheptanal is that described by the submitters. The present procedure starting from 2-methoxycyclooctanone oxime is superior to modifications employing 2-alkylamino- or 2-ethylthiocyclooctanone oxime in the Beckmann cleavage step. 

Application of the Beckmann cleavage route to the preparation of 18-norandrostan-17-ones185 (219) has been improved by intermediate formation of the 13-carboxy-13,17-seco-nitriles (217), which cyclized with base to form the 13a- and 13/3-isomers of the a-cyano-ketone (218) and thence the 18-nor-13a- and -13/3-androstan-17-ones (219).186 A similar reaction sequence has been employed for... 

Cyclobutane.—Further reports of grandisol (90) synthesis include Magnus s full paper (Vol. 6, p. 22) and an almost identical Japanese report of an earlier synthesis (Vol. 3, p. 25) based upon a dihydropyranone-ethylene cycloaddition.A third synthesis utilizes cyclopropanation of 4-methoxy-3,6,6-trimethylcyclohexa-2,4-dienone to yield (91) followed by rearrangement of the a-oxycyclopropylcarbinyl cation of (91) to (92). After reduction of the cyclobutanone, second-order Beckmann cleavage of the cyclopentanone oxime gave (93) from which grandisol (90) was readily obtained. 

Phosphorus pentachloride Chlorides from oximes Beckmann cleavage... 

Beckmann rearrangement, 4, 292 pyrolysis, 4, 202 synthesis, 4, 223 Wittig reaction, 4, 294 Wolff-Kishner reduction, 4, 291 Indole, 1-acyl-2,3-disubstituted photoisomerization, 4, 204 photo-Fries rearrangement, 4, 204 photoisomerization, 4, 42 synthesis, 4, 82 Indole, 2-acyl acidity, 4, 297 synthesis, 4, 337, 360 Indole, 3-acyl-acidity, 4, 297 cleavage, 4, 289 reduction, 4, 289 synthesis, 4, 360 Indole, 7-acyl-synthesis, 4, 246... 

BECKMANN Rearrangement or fragmentation Acid catalyzed rearrangement of oximes to amides or cleavage of oximes to nitnies... 

Fragmentation of the intermediate or concerted formation of nitriles from the activated oxime (Scheme 9, pathway 3) this is the Beckmann fragmentation. In some circumstances this pathway becomes dominant, particularly when there are quaternary carbons adjacent to the oxime. This transformation has found particular utility in ring-cleavage processes (sometimes called abnormal or second-order Beckmann rearrangements). 

Beckmann fragmentation is frequently applied to cyclic oximes resulting in a ring-cleavage reaction. Normally, a nitrile-alkene compound is obtained from the oxime and further transformation is usual. 

---