88909-09-5Relevant 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.
Synthesis of the Alkaloids Hopromine, Hoprominol and Hopromalinol, using Transamidation Methods
Crombie, Leslie,Haigh, David,Jones, Raymond C. F.,Mat-Zin, Ab. Rasid
, p. 2055 - 2068 (2007/10/02)
Synthesis of the unsymmetrical Homalium alkaloids hopromine, hoprominol and hopromalinol, in diastereoisomeric mixture form, is reported.The component eight-membered azalactams are first prepared.N-(3-Halogenopropyl)-4-pentyl- and -4-heptyl-azetidin-2-ones are aminated and ring expanded in liquid ammonia to give, after reductive methylation, the corresponding 4-alkyl-5-methyl-1,5-diazacyclooctan-2-ones.Synthesis of the 4-(2-hydroxyheptyl)-5-methyl-1,5-diazacyclooctan-2-one required for hoprominol and hopromalinol is carried out via 4-allyl β-lactam ring expansion to the eight-membered 4-allylazalactam, followed by methylation, epoxidation and epoxide opening with lithium dibutylcuprate.A similar epoxidation-cuprate sequence was carried out on the epoxypropyl β-lactam, as its N-tert-butyldimethylsilyl derivative, and led to a convenient copper-catalysed N- to O-migration of the protection; this migration is examined.Alkylation gave O-TBDMS-protected N-(3-chloropropyl)-4-(2-hydroxyheptyl)azetidin-2-one which could be aminated and transamidated in excellent yield, to give, after methylation, a superior sequence to the required eight-membered hydroxy azalactam.Although satisfactory for attachment of the first azalactam unit, a dibromobutane coupling system proved unreactive for the second.Couplings with unmethylated, methylated, and benzyloxycarbonyl-protected azalactams were examined using (E)-1,4-dibromobutene and (Z)-1,4-dichlorobutene as the bridging unit.Employing the latter, coupling the first N-methylated azalactam with potassium bis(trimethylsilyl)amide as the base, and then the second with bis(trimethylsilyl)amide-sodium hydride as the base system, provided a satisfactory synthetic outcome.Hydrogenation under acidic conditions gave the unsymmetrical structures hopromine, hoprominol and hopromalinol, as well as the more simple and symmetrical alkaloid, homaline.
SYNTHESIS OF UNSYMMETRICAL SPERMINE ALKALOIDS OF THE HOMALIUM GROUP
Crombie, Leslie,Jones, Raymond C. F.,Haigh, David
, p. 5147 - 5150 (2007/10/02)
Spermine alkaloids homaline, hopromalinol, hopromine, and hoprominol are prepared by sequential coupling of 4-substituted 5-methyl-1,5-diazacyclooctan-2-ones, available by transamidation from 4-substituted azetidin-2-ones, to 1,4-dichlorobut-2-ene.
Medium Ring Heterocycles: Transamidation Reactions of β-Lactams
Crombie, Leslie,Jones, Raymond C. F.,Osborne, Steven,Mat-Zin, Ab. Rasid
, p. 959 - 960 (2007/10/02)
Seven-, eight-, and nine-membered azalactams are easily prepared from azetidin-2-ones by transamidation via N-(halogenoalkyl) derivatives.
Synthesis of Homaline and epi-Homaline
Crombie, Leslie,Jones, Raymond C. F.,Mat-Zin, Ab. Rasid,Osborne, Steven
, p. 960 - 961 (2007/10/02)
5-Methyl-4-phenyl-1,5-diazacyclo-octan-2-one has been prepared by cyclisation of an acyclic precursor or by transamidation from 4-phenylazetidin-2-one, and converted into natural (-)-homaline and epi-homaline: the approach is applicable to the synthesis o
