KMnO4 revisited: Oxidation of aldehydes to carboxylic acids in the  -butyl alcohol - aqueous NaH2PO4 system

Abiko, Atsushi; Roberts, John C.; Takemasa, Toshiro; Masamune, Satoru

doi:10.1016/s0040-4039(00)84997-7

Cited by 182 publications

(67 citation statements)

References 14 publications

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“…Aldehydes 26, 27 were then oxidized with potassium permanganate in buffered aqueous tert-butyl alcohol. [32] By this procedure, the acids 28, 29 were obtained in 45% and 39% yields from the corresponding cyanoalcohols 8, 10. 1,3-Oxazolidines can be hydrolyzed to amino alcohols under mild conditions; thus acids 28 and 29 correspond to masked hydroxyethylene isosters.…”

Section: Resultsmentioning

confidence: 99%

Val‐Ala Dipeptide Isosteres by Hydrocyanation of α′‐Amino α,β‐Unsaturated Ketones − Control of Stereoselectivity by the N‐Protecting Group

et al. 2003

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Three diastereoisomeric hydroxyethylene isosters of the Val‐Ala dipeptide were synthesized from α,β‐unsaturated ketones 1 derived from N‐Boc‐ and N,N‐dibenzyl‐L‐valine. The enones were hydrocyanated with diethylaluminum cyanide to give the corresponding β‐cyano ketones with the stereoselectivity depending on the protecting group. N‐Boc protected enone 1a gave a 1:1 mixture of anti and syn adducts 4a, 5a while the corresponding N,N‐dibenzyl compound 1c gave a 6:1 mixture of anti, syn adducts 4c, 5c. Borohydride reduction of the resulting cyano ketones is also controlled by the protecting group, resulting in opposite stereoselectivities for N‐Boc and N,N‐dibenzyl compounds. The cyano alcohols thus obtained were converted, in several steps, into two series of enantiomerically pure hydroxyethylene isosters of the Val‐Ala dipeptide. In the first series the hydroxy group and the N‐terminal of the isoster are internally protected through the formation of an oxazolidine; in the second series the hydroxy group and the C‐terminal are protected as lactone. Two oxazolidines (28, 29), corresponding to syn,syn and syn,anti 4‐hydroxy‐5‐amino acid isosters, and three lactones (23−25), corresponding to syn,syn, syn,anti, and anti,anti isosters were obtained by this approach. (© Wiley‐VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003)

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Section: Resultsmentioning

confidence: 99%

Val‐Ala Dipeptide Isosteres by Hydrocyanation of α′‐Amino α,β‐Unsaturated Ketones − Control of Stereoselectivity by the N‐Protecting Group

et al. 2003

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“…yield. Finally, oxidation of the primary alcohol with Dess ± Martin periodinane, [25] followed by further oxidation [26] with aqueous KMnO 4 and exposure to diazomethane, gave the fully protected compound 45 b via the corresponding aldehyde and carboxylic acid, in 84 % overall yield from 44 b.…”

Section: Construction Of Ab/c-o-d/d-o-e Systemsmentioning

confidence: 99%

Total Synthesis of Vancomycin—Part 3: Synthesis of the Aglycon

et al. 1999

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The total synthesis of the vancomycin aglycon (2, Figure 1) is described. Construction of the key intermediate, tricyclic triazene 3 a (Figure 2), was accomplished in the orderThe C-O-D ring system 18 a (Scheme 2) was formed by using the triazene ring-closure methodology from a precursor (17) already possessing the AB biaryl fragment 6, synthesized by a Suzuki coupling reaction. At this point, a macrolactamization reaction furnished the AB ring system. Tripeptide 5 was incorporated in the main framework and the triazene ring-closure methodology was applied again to achieve the formation of D-O-E ring system, providing tricyclic triazene 3 a (Scheme 6). The latter was converted to the fully protected vancomycin aglycon 45 a by first introducing the phenolic moiety (derivative 43 a) and then oxidizing the AA-7 side chain (Scheme 12). Finally, global deprotection afforded vancomycins aglycon (2). Atropisomerization was successfully performed for D-O-E ring systems.

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“…The starting compound was glycosyl aldehyde 1, which was obtained in good yields from tetra-O-benzyl-dgluconolactone by addition of dithiane. [13] The oxidation of 1 under Masamune conditions [14] yielded the glycosylcarboxylic acid 2. The reductive amination of 1 did not afford the glycosylmethylamine 4 [15] selectively, but rather led to 4 and the alcohol 3.…”

Section: An Access To Glycoconjugate Libraries Through Multicomponentmentioning

confidence: 99%

An Access to Glycoconjugate Libraries through Multicomponent Reactions

Lockhoff

1998

Angewandte Chemie International Edition

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Four-component reactions: The Ugi reaction of four suitably functionalized carbohydrate derivatives (as a per-O-benzylated amine, an aldehyde, a carboxylic acid, and an isocyanide) allow the effective assembly of diverse compound libraries. The complex glycoconjugates formed can be deprotected (see the picture for an example), and the resulting glycomimetics are of high interest for screening purposes.

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KMnO4 revisited: Oxidation of aldehydes to carboxylic acids in the -butyl alcohol - aqueous NaH2PO4 system

Cited by 182 publications

References 14 publications

Val‐Ala Dipeptide Isosteres by Hydrocyanation of α′‐Amino α,β‐Unsaturated Ketones − Control of Stereoselectivity by the N‐Protecting Group

Val‐Ala Dipeptide Isosteres by Hydrocyanation of α′‐Amino α,β‐Unsaturated Ketones − Control of Stereoselectivity by the N‐Protecting Group

Total Synthesis of Vancomycin—Part 3: Synthesis of the Aglycon

An Access to Glycoconjugate Libraries through Multicomponent Reactions

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