89044-74-6Relevant articles and documents
Study of the Transamidative Ring Expansion of N-ω-Halogenoalkyl-β-lactams of Alkyl Chain Lengths 2-12 in Liquid Ammonia and Other Liquid Amines: Syntheses of 7-, 8- and 9-Membered 1,5-Diaza Cyclic Ketones, including Routes to (+/-)-Dihydroperiphylline and (+/-)-Celabenzine
Begley, Michael J.,Crombie, Leslie,Haigh, David,Jones, Raymond C. F.,Osborne, Steven,Webster, Richard A. B.
, p. 2027 - 2046 (2007/10/02)
N-(3-Halogenopropyl)-4-phenylazetidin-2-ones undergo amination in liquid ammonia followed by transamidative ring expansion to give the eight-membered 4-phenyl-1,5-diazacyclooctan-2-one in excellent yield.Ring expansion of the amines in liquid ammonia is found to be much more effective than in hydrocarbon solvents.Formation of 7-, 8-, and 9-membered azalactams from the requisite ω-halogenoalkyl-β-lactams is an excellent synthetic process, though it is not applicable to 10-membered rings.In the case of rings of 13-, 15- and 17-members, although amination and apparent expansion takes place, the large rings appear not to be stable to ammonia and the final products are acyclic amides.N--4-phenylazetidin-2-one satisfactorily forms a 9-membered (Z)-olefinic azalactam, but the (E)-isomer gives an acyclic amino amide.By using alkyl-substituted β-lactam side-chains, C-substituted medium rings can be obtained; the relative instability of N-acyl β-lactams to ammonia, however, leads to acylamino amides rather than expanded rings.Employing ethylamine in place of ammonia, it is shown that N-ethylated azalactams are formed satisfactorily, and using allylamine, N-allyl medium rings capable of further elaboration are obtained.The chemistry of these systems is discussed.Using transamidation in liquid ammonia, a short synthesis of the 9-membered spermidine alkaloid (+/-)-dihydroperiphylline is reported.Synthesis of key intermediates, whose transformation into the 13-membered alkaloids of the celabenzine group has already been effected, has been carried out.X-Ray single-crystal structure determinations for 4-phenyl-1,5-diazacyclononan-2-one, trans-4-phenyl-8-methyl-1,5-diazacyclooctan-2-one and (Z)-4-phenyl-1,5-diazacyclonon-7-en-2-one are reported, and comment is made on certain conformational features.
