title: Efficient method for the deprotection of tert-butyldimethylsilyl ethers with TiCl4-Lewis base complexes: application to the synthesis of 1beta-methylcarbapenems.
abstract: TiCl4-Lewis base (AcOEt, CH3NO2) complexes smoothly deprotected tert-butyldimethylsilyl (TBDMS) ethers. The reaction velocity with these complexes, which seemed less reactive due to the influence of Lewis bases, was considerably greater than that with TiCl4 alone. Selective desilylations between aliphatic and aromatic TBDMS ethers (1 and 5), between 1 and benzyl, allyl, tosyl, methoxyphenyl, and chloroacetyl ethers (13, 14, 15, 16, and 17), and between TBDMS and TBDPS ethers (18 and 19) were successfully performed. Desilylation of TBDMS-aldol, acyloin, and beta-lactam analogues 9-12 proceeded smoothly due to anchimeric assistance by the neighboring carbonyl groups. The present method was successfully applied to the practical synthesis of 1beta-methylcarbapenems 20a'-f'.
authors.affiliation: Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Iida
authors.forename: Hiroki
authors.initials: H
authors.lastname: Okazaki
authors.forename: Tomonori
authors.initials: T
authors.lastname: Misaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Sunagawa
authors.forename: Akira
authors.initials: A
authors.lastname: Sasaki
authors.forename: Yoo
authors.initials: Y
authors.lastname: Tanabe
mesh_terms: D015780:Carbapenems / Q000138:chemical synthesis* / Q000737:chemistry; D004987:Ethers / Q000737:chemistry*; D015394:Molecular Structure; D009573:Nitrites / Q000737:chemistry*; D017646:Organosilicon Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*
chemical_list: D015780:Carbapenems; D004987:Ethers; D009573:Nitrites; D017646:Organosilicon Compounds; C009660:t-butyldimethylsilyl compounds; C025096:titanium tetrachloride; C037538:methyl nitrite; D014025:Titanium