Synthesis of Medium-Sized Ring Lactams

Nubbemeyer, U.

doi:10.1007/3-540-44726-1_4

Cited by 133 publications

(50 citation statements)

References 68 publications

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“…However, it should be taken into account that in ω-amino acids intramolecular condensation with formation of the lactam competes with the growing chain to give a linear polymer. 28 Thus, attempted polymerization of active esters of tetra-O-methyl-6-amino-6-deoxy-D-gluconic 19 and D-galactonic 25 acids led to lactam formation.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and polymerization of conveniently substituted 6-amino-6-deoxy-D-galactonic acid derivatives

Zaliz¹,

Erra‐Balsells²,

Nonami³

et al. 2005

Arkivoc

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Methyl 6-azido-6-deoxy-2,3:4,5-di-O-isopropylidene-D-galactonate (1), prepared in two steps from D-galactono-1,4-lactone, was hydrolyzed to the corresponding acid 2, which was esterified with phenol (PhOH) in the presence of dicyclohexylcarbodiimide (DCC) to give the phenyl ester 3. Hydrogenolysis of the azide function of 3 yielded the hydrochloride derivative of the amino acid 4. Compound 4 is conveniently substituted for the polycondensation; therefore, this reaction was conducted using DMF as solvent and N,N-diisopropylethylamine as a basic catalyst. The MALDI-TOF mass spectrum of the isolated product (5) indicated that this was a mixture of the cyclic trimer (M + Na + , 793.7) and linear oligomers (from the tetramer to the tetradecamer). To favor the linear polymerization the dimeric amino acid 10 was prepared starting from 2. Thus, hydrogenation of 2 gave the amino acid 6, and treatment of 2 with pentachlorophenol-DCC gave the pentachlorophenyl ester 7. Coupling of 6 with 7 in the presence of DCC gave the dimer 8, which was converted (PhOH, DCC) into 9. Hydrogenolysis of 9 afforded the dimeric amino acid 10, which was polymerized under the conditions employed for 4. The resulting polyamide 11 was highly soluble in common organic solvents, and its molecular weight was established by MALDI-TOF MS and size exclusion chromatography (M w = 2700).

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Section: Methodsmentioning

confidence: 99%

Synthesis and polymerization of conveniently substituted 6-amino-6-deoxy-D-galactonic acid derivatives

Zaliz¹,

Erra‐Balsells²,

Nonami³

et al. 2005

Arkivoc

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“…[9] Interestingly, the majority of previous syntheses feature a reductive ring opening of a 5-6 system to access the 9-membered ring, presumably due to the notorious difficulty associated with the formation of medium sized rings. [10] In light of these pioneering efforts, we envisioned a novel approach to (±)-quebrachamine (1) that confronts formation of the 9-membered ring through an early retrosynthetic disconnection that identified two strategic bonds (Scheme 2). Either of these disconnections would allow for a variety of Friedel-Crafts acylation or N-alkylation type strategies to be explored, while greatly simplifying the synthetic target to advanced key intermediate 2.…”

Section: Scheme 1 Potential Natural Product Targets Frommentioning

confidence: 99%

Total Synthesis of (±)‐Quebrachamine via [3+2] Cycloaddition and Efficient Chloroacetamide Photocyclization

Bajtos

Pagenkopf

2009

Eur J Org Chem

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The total synthesis of (±)‐quebrachamine has been completed in 13 linear steps and 17.8 % overall yield. The indole core was constructed via a formal [3+2] dipolar cycloaddition between a functionalized nitrile and donor‐acceptor cyclopropane, and the synthetically challenging nine‐membered ring was secured by an efficient chloroacetamide photocyclization.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…Uma das mais elegantes maneiras de se construir uma nova ligação C-C é através de um rearranjo sigmatrópico [3,3], chamado rearranjo de Claisen 91,92 . O rearranjo de ceteno-acetais vinil-e alquenil-substituídos, preparados in situ a partir de fenil seleno-acetais ou de carbonatos, vem sendo bastante explorado na síntese de lactonas de anel mé-dio, pelo grupo de Holmes e Burton [93][94][95][96][97][98] .…”

Section: Rearranjo De Claisenunclassified

“…A olefinação de carbonatos cíclicos de 6 e 7 membros, promovida pelo dimetiltitanoceno, levou à geração in situ dos respectivos ceteno-acetais, os quais, por sua vez, forneceram lactonas de 8 e 9 membros, através do rearranjo sigmatrópico [3,3] (Esquema 44). Uma aplicação da metodologia acima descrita à síntese das octalactinas A e B foi recentemente descrita pelo grupo 98 .…”

Section: Rearranjo De Claisenunclassified