Simple and Efficient N-Acylation Reactions of Chiral Oxazolidine Auxiliaries

Ager, David J.; Allen, David R.; Schaad, David R.

doi:10.1055/s-1996-4402

Cited by 65 publications

(38 citation statements)

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“…The synthesis started with the preparation of silyl ketene N,O-acetal 7 through g-deprotonation and O-tert-butyldimethylsilylation of the known building block 6 (Scheme 2). [13] Subsequently, anti-selective VMAR [14] was performed between 7 and freshly prepared (E)-3-iodo-2-methylacrylaldehyde in the presence of TiCl 4 as a Lewis acid. In searching for the best reaction conditions, we found that a higher reaction concentration led to the best yield and diastereoselectivity (47 %, d.r.…”

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confidence: 99%

Total Synthesis of the Protected Aglycon of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)

2014

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Fidaxomicin, also known as tiacumicin B or lipiarmycin A3, is a novel macrocyclic antibiotic that is used in hospitals for the treatment of Clostridium difficile infections. This natural product has also been shown to have excellent bactericidal activity against multidrug-resistant Mycobacterium tuberculosis. In spite of its attractive biological activity, no total synthesis has been reported to date. The enantioselective synthesis of the central 18-membered macrolactone is reported herein. The key reactions include ring-closing metathesis between a terminal olefin and a dienoate moiety for macrocyclization, a vinylogous Mukaiyama aldol reaction, and a Stille coupling reaction of sterically demanding substrates. The retrosynthesis involves three medium-sized fragments, thus leading to a flexible yet convergent synthetic route. COMMUNICATION Total Synthesis of the Protected Aglycon of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)Hideki Miyatake-Ondozabal, Elias Kaufmann and Karl Gademann* Dedication ((optional)) Abstract: Fidaxomicin, also known as tiacumicin B or lipiarmycin A3, is a novel macrocyclic antibiotic used in hospitals for the treatment of Clostridium difficile infections. This natural product has also been shown to have an excellent bactericidal activity against multi-drug resistant Mycobacterium tuberculosis. In spite of its attractive biological activity, no total synthesis has ever been reported to date. Herein, we report the enantioselective synthesis of the central 18-membered macrolactone. The noteworthy reactions include ringclosing metathesis between a terminal olefin and a dienoate moiety for macrocyclization, a vinylogous Mukaiyama aldol reaction, and a Stille coupling reaction of sterically demanding substrates. The retrosynthesis comprises of three medium sized fragments leading to a flexible yet convergent synthetic route.

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confidence: 99%

Total Synthesis of the Protected Aglycon of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)

2014

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“…The achiral N-acyloxazolidinone derivative 9, 35 33 were prepared according to published procedures.…”

Section: H Nmr Andmentioning

confidence: 99%

Stereoselective addition of chiral titanium enolates to 5-substituted five-membered oxocarbenium ions

Pilli¹,

Riatto²

2008

J. Braz. Chem. Soc.

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O curso estereoquímico da adição de enolatos de titânio quirais a -lactóis derivados do ácido (S)-glutâmico foi investigado. Quando -lactóis 5-substituídos foram tratados com enolatos de titânio quirais derivados de N-acetil-, N-propionil-, N-bromoacetil-e N-fenilacetil oxazolidin-2-onas somente dois diastereoisômeros foram obtidos, revelando um completo controle facial pelo enolato de titânio, enquanto que a discriminação facial do íon oxocarbênio mostrou-se dependente da natureza do grupo R 3 do enolato. Dessililação com HF/CH 3 CN aquoso, seguida de redução com LiBH 4 , forneceu eficientemente dióis tetraidrofurânicos trans-2,5-dissubstituídos e recuperação do auxiliar quiral.The sterochemical outcome of the addition of chiral titanium enolates to -lactols derived from (S)-glutamic acid were examined. When 5-substituted -lactols were treated with chiral titanium enolates of N-acetyl-, N-propionyl-, N-bromoacetyl-and N-phenylacetyl oxazolidin-2-ones, only two diastereoisomers were obtained, revealing complete facial control by the chiral titanium enolate while the oxocarbenium ion facial discrimination was dependent on the nature of the enolate R 3 substituent. After desilylation with aqueous HF/CH 3 CN, LiBH 4 reduction allowed the efficient preparation of the corresponding trans-2,5-disubstituted tetrahydrofuran diols and recovery of the chiral auxiliary.

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“…2 A simplified procedure for the N-acylation of oxazolidin-2-one chiral auxiliaries has also been reported. 3 Recently, we have been able to take advantage of these acidic NOH protons in 1-methyl-2,5-bis(4-phenylurazoyly) pyrrole and synthesize novel polymers via N-alkylation and N-acylation reactions. 4,5 The polymerization of 4-phenylurazole (PHU) with phosgene, terephthaloyl chloride, and epichlorohydrin has been reported to produce insoluble polymers.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of new polyamides derived from 4‐(4′‐aminophenyl)urazole and aliphatic diacid chlorides

Mallakpour

Rafiee

2004

J of Applied Polymer Sci

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4-(4Ј-Aminophenyl)urazole (AmPU) was prepared from 4-nitrobenzoic acid in six steps. The reaction of AmPU with acetyl chloride was performed in N,N-dimethylacetamide solutions at different ratios, and the resulting disubstituted and trisubstituted amide derivatives were obtained in high yields and were used as models for polymerization reactions. Polycondensation reactions of AmPU with succinyl chloride, suberoyl chloride, and sebacoyl chloride were performed with conventional solution polymerization techniques in the presence of different catalysts, such as pyridine, triethylamine, and dibutyltin dilaurate, and led to the formation of novel aliphatic polyamides. The resulting novel polyamides had inherent viscosities of 0.11-0.22 dL/g in dimethylformamide or H 2 SO 4 at 25°C. These polyamides were characterized with IR, 1 H-NMR, elemental analysis, and thermogravimetric analysis. Some physical properties and structural characterization of these novel polyamides are reported.

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Simple and Efficient N-Acylation Reactions of Chiral Oxazolidine Auxiliaries

Cited by 65 publications

References 0 publications

Total Synthesis of the Protected Aglycon of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)

Total Synthesis of the Protected Aglycon of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)

Stereoselective addition of chiral titanium enolates to 5-substituted five-membered oxocarbenium ions

Synthesis and characterization of new polyamides derived from 4‐(4′‐aminophenyl)urazole and aliphatic diacid chlorides

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