메뉴 건너뛰기




Volumn 61, Issue 52, 2005, Pages 12227-12237

Efficient chemoselective deprotection of silyl ethers using catalytic 1-chloroethyl chloroformate in methanol

Author keywords

1 Chloroethyl chloroformate; Catalytic; Chemoselective; Desilylation; Silyl ethers

Indexed keywords

1 CHLOROETHYLCHLOROFORMATE; ACID; ALCOHOL DERIVATIVE; FORMIC ACID DERIVATIVE; METHANOL; SILANE DERIVATIVE; UNCLASSIFIED DRUG;

EID: 28444478009     PISSN: 00404020     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tet.2005.10.043     Document Type: Article
Times cited : (26)

References (84)
  • 33
    • 28444476319 scopus 로고    scopus 로고
    • note
    • Determined from GC analysis using HP-5 column (Crosslinked 5% PH ME Polysiloxane).
  • 34
    • 28444468540 scopus 로고    scopus 로고
    • note
    • We examined the selective TES cleavage over TBDMS with lower amount of thionyl chloride (0.01, 0.02, 0.025 mol%), and the results were still less desirable than those obtained with 1-chloroethyl chloroformate (83-89% yield vs 93-95%, respectively).
  • 35
    • 28444460474 scopus 로고    scopus 로고
    • note
    • Per suggestion from one of the reviewers, commercially available 1.25 M HCl in methanol (Fluka) was examined in the desilylation. By employing varying amounts of HCl in methanol from 0.025, 0.05, 0.1, to 0.2 mol%, we obtained mono-desilylated alcohol (Table 1, 1 ) in 85, 89, 86, and 76% yields, respectively, along with diols. These yields were 8-21% lower than those obtained with CEC. When a very small amount (∼0.01 mol%) of methanolic HCl was employed, the yield of TES removal was less than 6%, and most starting material was recovered. We also carried out selective TBDMS removal over TIPS with 8a with varying amount of HCl, and yields were 73-83%, which are again lower than those obtained with CEC.
  • 36
    • 21544460203 scopus 로고    scopus 로고
    • For recent reports on successful application of in situ generated hydrogen halides to selective organic transformations, see: (a) C.-E. Yeom, S.Y. Lee, Y.J. Kim, and B.M. Kim Synlett 2005 1527
    • (2005) Synlett , pp. 1527
    • Yeom, C.-E.1    Lee, S.Y.2    Kim, Y.J.3    Kim, B.M.4
  • 44
    • 3042662232 scopus 로고    scopus 로고
    • Use of Pd/C at desilylation exhibited remarkable commercial supplier-dependent disparity. See: (a) T. Ikawa, H. Sajiki, and K. Hirota Tetrahedron 60 2004 6189
    • (2004) Tetrahedron , vol.60 , pp. 6189
    • Ikawa, T.1    Sajiki, H.2    Hirota, K.3
  • 48
    • 0000054361 scopus 로고    scopus 로고
    • Reports on chemoselective cleavage of aliphatic TES over phenolic one are rare and in case of TBDPS, only a few examples have been reported, see: (a) T. Oriyama, Y. Kobayashi, and K. Noda Synlett 1998 1047
    • (1998) Synlett , pp. 1047
    • Oriyama, T.1    Kobayashi, Y.2    Noda, K.3


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.