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Synlett
Volumn , Issue 4, 2009, Pages 603-606
Tandem one-pot acetalation-acetylation for direct access to differentially protected thioglycosides and O-glycosides with p-toluenesulfonic acid
Author keywords

Acetals; Glycosides; Oligosaccharides; Protecting group; Tandem
Indexed keywords

EID: 62349087420     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-1087913     Document Type: Article
Times cited : (14)
References (49)
  • 37
    • 0031566322 scopus 로고    scopus 로고
    • Compound 4 was obtained by literature procedure reported in: Ahn, Y. M.; Gray, G. R. Carbohydr. Res. 1997, 298, 279.
    • Compound 4 was obtained by literature procedure reported in: Ahn, Y. M.; Gray, G. R. Carbohydr. Res. 1997, 298, 279.
  • 38
    • 62349109891 scopus 로고    scopus 로고
    • Unprotected thioglycosides 5-10 were derived from the corresponding peracetyl thioglycosides by Zemplèn deacetylation. Peracetyl thioglycosides were prepared by literature procedure reported in ref. 20.
    • Unprotected thioglycosides 5-10 were derived from the corresponding peracetyl thioglycosides by Zemplèn deacetylation. Peracetyl thioglycosides were prepared by literature procedure reported in ref. 20.
  • 39
    • 62349101186 scopus 로고    scopus 로고
    • Compound 12 was obtained by literature procedure reported in: Kondo, H.; Ichikawa, Y.; Wong, C.-H. J. Am. Chem. Soc. 1992, 114, 8148.
    • Compound 12 was obtained by literature procedure reported in: Kondo, H.; Ichikawa, Y.; Wong, C.-H. J. Am. Chem. Soc. 1992, 114, 8148.
  • 40
    • 62349098024 scopus 로고    scopus 로고
    • Preparatory procedures of compounds 3 and 11 were described in supporting information.
    • Preparatory procedures of compounds 3 and 11 were described in supporting information.
  • 43
    • 62349112515 scopus 로고    scopus 로고
    • General One-Pot Benzylidenation-Acetylation Procedure for the Preparation of 2 and 13-20 TsOH (10-32 mol, Table 1) was added into a stirring mixture of carbohydrate substrate (1.0 equiv of methyl α-D-glucopyranoside, 3-8, 10, or 11) and PhCH(OMe)2 (1.5 equiv) in MeCN under N2. Upon complete conversion into benzylidene acetal intermediate as assessed by TLC, Ac 2O (1.5 equiv per OH, total OH equals to the sum of OH of acetal intermediate plus MeOH released from acetalating reagent) was added, and the reaction temperature was brought up to 40 or 50°C (Table 1, Specific reaction conditions are detailed in the supporting information. Upon complete acetylation as assessed by TLC, excess EtOAc (4 x of MeCN used) was added to the mixture, which was then washed with sat. NaHCO3, brine, dried over MgSO4, and concentrated for purification by flash column chromatography over SiO2. El
    • 2. Elution with EtOAc-hexane mixture afforded the compounds 2 and 13-20.
  • 44
    • 62349092640 scopus 로고    scopus 로고
    • General One-Pot Isopropylidenation-Acetylation Procedure for Preparation of 21-24 TsOH (5-10 mol, Table 1) was added into a stirring mixture of unprotected thioglycoside (1.0 equiv of 5, 6, 9, or NANA ester 12, and Me2CH(OMe)2 (1.5 equiv) in acetone. The mixture was stirred at r.t. or 40°C under N2. Upon complete conversion into glycosyl ketal intermediate as assessed by TLC, Ac2O (1.5 equiv per OH, total OH equals to OH from glycosyl acetal intermediate plus MeOH released from acetalating reagent) was added, and the reaction temperature was brought up to 35 or 40°C (Table 1, Specific reaction conditions for preparation of compounds 21-24 were detailed in the supporting information. Upon complete acetylation as assessed by TLC, excess EtOAc (4 x of MeCN used) was added to the mixture, which was then washed with sat. NaHCO3, brine, dried over MgSO4, and concentrated for
    • 2. Elution with EtOAc-hexane mixture afforded compounds 21-24.
  • 49
    • 62349122105 scopus 로고    scopus 로고
    • For acid-catalyzed one-pot acetalation-acetylation, unnecessary prolonged reaction time would compromise the yield of reaction due to the cleavage of the acetal function
    • For acid-catalyzed one-pot acetalation-acetylation, unnecessary prolonged reaction time would compromise the yield of reaction due to the cleavage of the acetal function.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.