- A New Method for the Carbon-extension Reactions of Azetidin-2-ones at the 4-Position
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High yields of 4-alkyl-, 4-allyl-, 4-vinyl-, or 4-ethynynl-azetidin-2-ones are obtained by treating 4-sulphonylazetidin-2-ones with either lithium organocuprates or Grignard reagents, but yields from 4-acetoxyazetidin-2-one with Grignard reagents are low.
- Kobayashi, Takeo,Ishida, Nobory,Hiraoka, Tetsuo
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- Amidoalkylations with Allylic Silanes: a Facile Synthesis of the Carbapenem System
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Amidoalkylation reactions with allylic silanes provide a direct route to the carbapenem ring system.
- Kraus, George A.,Neuenschwander, Kent
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- Ring-closing metathesis of vinyl fluorides towards α-fluorinated α,β-unsaturated lactams and lactones
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Ring-closing olefin metathesis reactions (RCM) using Grubbs II or Hoveyda's catalysts have been applied to a series of N-alkenyl-N-benzyl-α-fluoroacrylamides. α-Fluoro-α,β-unsaturated γ- or δ-lactams incorporating a fluorinated double bond were obtained in moderate to good yields, depending on the nature of substituents on the benzyl ring. The corresponding seven- and eight-membered lactams were not formed under similar conditions. When the N-benzyl group was replaced by an N-tosyl group, the corresponding ε-lactam was also formed in 38% yield. When N-(2-fluoroallyl) derivatives were used instead of fluoroacryloyl derivatives, six-, seven-, and eight-membered N-heterocycles were obtained in low yields. This method was also used to synthesize fluorinated α,β-unsaturated analogues of pyrrolizidine and indolizidine alkaloids from prolinol, and also to synthesize N-benzyl-3-fluoroquinolone in three steps from commercially available 2-vinylaniline in 44% overall yield. Also 3-fluorocoumarin and 3-fluorochromene were prepared from ovinylphenol, and 3-fluoro-benzoxepine was available from o-allylphenol.
- Marhold, Michael,Stillig, Christian,Fr?hlich, Roland,Haufe, Günter
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supporting information
p. 5777 - 5785
(2014/10/15)
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- β-, γ- and δ-Lactams as conformational constraints in ring-closing metathesis
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The azabicycloalkenones 5, 6 and 7 were formed in excellent yields via ring-closing metathesis of the bis-alkenyl precursors 1, 2 and 3.
- Tarling, Chris A.,Holmes, Andrew B.,Markwell, Roger E.,Pearson, Neil D.
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p. 1695 - 1701
(2007/10/03)
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- Rapid entry into mono-, bi-, and tricyclic β-lactam arrays via alkene metathesis
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4-Acetoxy-2-azetidinone and (3R,4R)-4-acetoxy-3-[(1R)-1-(tert- butyldimethylsilyl)-oxyethyl]-2-azetidinone were converted into 4-alkenyloxy- , 4-(N-allyltoluene-4-sulfonamido)-, 4-(allylthio)-, and 4-alkenyl-2- azetidinone systems. In addition, 4-acetoxy-2-azetidinone and (3R,4R)-4- acetoxy-3-[(1R)-1-(tert-butyldimethylsilyl)-oxyethyl]-2-azetidinone were converted into β-lactam dienes via sequential C-4 substitution using unsaturated alcohols, allyl mercaptan, N-allyltoluene-4-sulfonamide, and allyl(chloro)dimethylsilane followed by N-allylation. Crossed metathesis of β-lactam alkenes with styrene partners and ring closing metathesis of β- lactam dienes using the Schrock [(CF3)2MeCO]2Mo(=CHCMe2Ph)(=NC6H3-2,6- iso-Pr2) (1) or Grubbs Cl2(Cy3P)2Ru=CHPh (2) carbenes gave diverse monocyclic and bicyclic β-lactam systems including derivatives of 1- azabicyclo-[4.2.0]octan-8-one, 1-azabicyclo[5.2.0]nonan-9-one and its 6- thia, 6-aza, and 6-oxa analogues, 7-oxa-1-azabicyclo[6.2.0]octan-10-one,8- oxa-1-azabicyclo[7.2.0]octan-11-one, and 9-oxa-1-azabicyclo[8.2.0]octan-12- one. Ring-closing enyne metathesis and tandem ring-closing enyne and diene metathetic reactions were used to produce bicyclic β-lactam conjugated dienes as exemplified by the conversion of (3S,4R)-(-)-3-[(1R)-(tert- butyldimethylsilyl)oxyethyl]-1-(5-oxa-oct-7-en-2-yn-1-yl)-4-(2-propenyl)- azetidin-2-one (83) into (6R,7S)-(+)-7-[(1R)-(tert- butyldimethylsilyl)oxyethyl]-3-[(2,5-dihydro)-3-furanyl]-1- azabicyclo[4.2.0]oct-3-en-8-one (98).
- Barrett, Anthony G. M.,Baugh, Simon P. D.,Christopher Braddock,Flack, Kevin,Gibson, Vernon C.,Giles, Matthew R.,Marshall, Edward L.,Procopiou, Panayiotis A.,White, Andrew J. P.,Williams, David J.
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p. 7893 - 7907
(2007/10/03)
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- Highly functionalised monocyclic and bicyclic β-lactams via alkene metathesis
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Both monocyclic and bicyclic β-lactam systems are prepared via alkene metathesis reactions using Mo(=CHCPhMe2)-(=NC6H3Pr(i)20[(OCMe(CF3)2]2 or Ru(=CHPh)Cl2(PCy3/
- Barrett, Anthony G. M.,Baugh, Simon P. D.,Gibson, Vernon C.,Giles, Matthew R.,Marshall, Edward L.,Procopiou, Panayiotis A.
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p. 155 - 156
(2007/10/03)
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- A new access to racemic carbacephems
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A new approach to carbaccphems is reported involving the formation of the six-membered ring by cyclization of N-acyliminium ions. With methylene iminium species the reaction appeared general, while with (methoxycarbonyl)methylene iminium intermediates the
- Oumoch, Said,Rousseau, Gerard
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p. 997 - 1003
(2007/10/03)
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- Synthesis of the Alkaloids Hopromine, Hoprominol and Hopromalinol, using Transamidation Methods
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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.
- Crombie, Leslie,Haigh, David,Jones, Raymond C. F.,Mat-Zin, Ab. Rasid
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p. 2055 - 2068
(2007/10/02)
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- BARBIER-TYPE ALLYLATION OF ACETALS WITH ALLYL BROMIDE IN A Pb/Al BIMETAL REDOX SYSTEM
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A novel mono and/or double allylation of acetals is achieved by the action of allyl bromide, aluminium metal, and a catalytic amount of PbBr2 and AlBr3 in tetrahydrofuran.
- Tanaka,Hideo,Yamashita, Shiro,Ikemoto, Youichi,Torii, Sigeru
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p. 1721 - 1724
(2007/10/02)
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- Synthesis and Reactivity of Novel Bicyclic &β-Lactams
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The synthesis of the novel 8-oxo-1,3-diazabicyclooct-2-ene-2-carboxylates 1 is described as well as their enhanced reactivity under physiological conditions, compared with similar β-lactam compounds.
- Pfaendler, Rudolf,Strasser, Rupert
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p. 911 - 920
(2007/10/02)
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- SYNTHESIS OF UNSYMMETRICAL SPERMINE ALKALOIDS OF THE HOMALIUM GROUP
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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.
- Crombie, Leslie,Jones, Raymond C. F.,Haigh, David
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p. 5147 - 5150
(2007/10/02)
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- SYNTHESIS OF 4-SUBSTITUED 2-AZETIDIONES
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4-Substitued 2-azetidiones were obtained in excellent yields from the reaction of various cuprates with 4-acetoxy-2-azetidinone.
- Hua, Duy H.,Verma, Akhilkumar
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p. 547 - 550
(2007/10/02)
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- 4-Allyl azetidinone intermediate for β-lactam antibacterial agents
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Compounds are provided of the formula (II): STR1 wherein R1 is a group such that CO2 R1 is an ester group and A1 is a hydrogen atom or a methyl group. These compounds possess antibacterial activity. The preparat
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- SYNTHESE FUER OPTISCH AKTIVE (6R)-SUBSTITUIERTE (5R) CARBAPENEME
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The synthesis of an enantiomerically pure (5R,6R)-carbapenem 2 is described.The key step consists of a stereospecific C-C-coupling in 4-position of the lactam 9 by means of cuprates.
- Koller,W,Linkies, A.,Pietsch, H.,Rehling, H.,Reuschling, D.
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p. 1545 - 1548
(2007/10/02)
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- β-Lactam antibacterial agents
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Compounds are described of the formula (II): STR1 wherein R1 is a group such that CO2 R1 is an ester group; A1 is a hydrogen atom; and A2 is a group CR2 R3 R4 wherein
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- Olivanic Acid Analogues. Part 1. Total Synthesis of the 7-Oxo-1-azabicyclohept-2-ene-2-carboxylate System and Some Related β-Lactams
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4-Allylazetidin-2-one, prepared from penta-1,4-diene and chlorosulphonyl isocyanate, has been used to synthesise the parent 7-oxo-1-azabicyclohept-2-ene-2-carboxylate system of the naturally occurring olivanic acids, using an intramolecular Wittig reaction to construct the 2,3-double bond.Cyclisation of ketones derived from the 4-allyl grouping produced 3-substituted derivatives, while use of the azetidin-2-one prepared from hexa-1,5-diene and chlorosulphonyl isocyanate has given the homologous 8-oxo-1-azabicyclooct-2-ene system.
- Bateson, John H.,Baxter, Andrew J. G.,Roberts, Patricia M.,Smale, Terence C.,Southgate, Robert
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p. 3242 - 3249
(2007/10/02)
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- Bicyclic β-lactam antibiotics
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Compounds of the formula (I): STR1 wherein G is hydrogen, alkyl, alkenyl, substituted alkyl or substituted alkenyl, R1 is alkyl or aryl, substituted alkyl or substituted aryl, and R is an organic group such that --CO2 R is an ester group are produced. The compounds are useful as antibacterial and β-lactamase inhibitory agents.
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