A Facile Cleavage of Benzylidene Acetals With Diisobutylaluminum Hydride

Takano, Seiichi; Akiyama, Masashi; Sato, Seiji; Ogasawara, Kunio

doi:10.1246/cl.1983.1593

Cited by 196 publications

(87 citation statements)

References 6 publications

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“…15 In order to introduce the requisite PMB group onto the secondary-OH of this diol, recourse was made to reduction of the p-methoxybenzylidene acetal 25 with DIBAL, 17 which again proceeded with excellent regiocontrol. A Swern oxidation 18 of 26 then completed our synthesis of aldehyde 15.…”

Section: Jonathanmentioning

confidence: 99%

Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of β-catenin/TCF4- and E2F-mediated gene transcription

2010

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Section: Jonathanmentioning

confidence: 99%

Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of β-catenin/TCF4- and E2F-mediated gene transcription

2010

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“…In view of the practicalities, the stannylidene-mediated benzylation was used for conversion to 17. The C-2 hydroxyl group of 17 was protected with an MBn group in the conventional manner (MBnCl, NaH/DMF), and then the 4,6-benzylidene group was reductively opened upon treatment with DIBAL-H in toluene [23] to yield the 6-OH glucosyl acceptor 8. The position of the resulting free hydroxyl group was confirmed by NMR analysis of compound 8 and the corresponding acetylated derivative 8'.…”

Section: Resultsmentioning

confidence: 99%

A First Total Synthesis of Ganglioside HLG‐2

Iwayama

Ando

Ishida

et al. 2009

Chemistry A European J

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A neuritegenic ganglioside from sea cucumber, HLG-2 (see figure), has been synthesized for the first time. The unique tandem of sialic acids, Neu5Gc-alpha(2,4)-NeuAc, was established by the combination of a reactive N-Troc sialyl donor and a 1,5-lactamized sialyl acceptor. The ceramide counterpart was assembled in a stereoselective manner. Direct connection of the trisaccharide and the ceramide successfully afforded a precursor of HLG-2, which was converted to ganglioside HLG-2 in pure form.A first synthesis of the neuritegenic ganglioside HLG-2, which was identified in extracts of the sea cucumber Holothuria leucospilota, is described. The characteristic sequence of the trisaccharide part, alpha-N-glycolylsialyl-(2,4)-alpha-N-acetylsialyl-(2,6)-glucoside, was efficiently assembled by coupling of a highly active N-2,2,2-trichloroethoxycarbonyl (Troc)-protected sialyl donor and a 1,5-lactamized sialyl acceptor with high stereoselectivity. The corresponding trisaccharyl imidate donor was directly glycosidated with the primary hydroxyl group of the ceramide part, producing protected HLG-2 in relatively high yield, global deprotection of which furnished ganglioside HLG-2 in highly pure form.

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“…[21] Oxidation to the aldehyde and treatment with the appropriate lithium acetylide provided diastereomeric mixtures of propargylic alcohols 5.…”

Section: Resultsmentioning

confidence: 99%

[1,3]‐Transfer of Chirality during the Nicholas Reaction in γ‐Benzyloxy Propargylic Alcohols

Díaz

Ramírez

Martı́n

2006

Chemistry A European J

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A highly regio- and stereoselective intramolecular [1,5]-hydrogen-transfer process is described. Treatment of gamma-benzyl-protected Co2(CO)6-alpha,gamma-acetylenic diols with BF3 x OEt2 provides bis-homopropargylic alcohols. The reaction occurs within seconds, tolerates a wide range of functionalities, and provides good yields. When the ether group is located at a stereochemically defined carbon atom, the rearrangement occurs with high stereoselectivity, transferring the chirality of the carbinol center to the newly created stereocenter. The cleavage of the benzyloxy group is totally regioselective when additional benzyl ethers are present. The scope and limitations of this novel process in densely substituted substrates are evaluated, and possible competitive reactions and/or stereochemical influences are also described. A mechanism based on a highly ordered chair-like transition state substantiated by a theoretical study is also included.

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A Facile Cleavage of Benzylidene Acetals With Diisobutylaluminum Hydride

Cited by 196 publications

References 6 publications

Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of β-catenin/TCF4- and E2F-mediated gene transcription

Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of β-catenin/TCF4- and E2F-mediated gene transcription

A First Total Synthesis of Ganglioside HLG‐2

[1,3]‐Transfer of Chirality during the Nicholas Reaction in γ‐Benzyloxy Propargylic Alcohols

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