78926-09-7Relevant articles and documents
Visible-Light-Induced [4+2] Annulation of Thiophenes and Alkynes to Construct Benzene Rings
Song, Chunlan,Dong, Xin,Wang, Zhongjie,Liu, Kun,Chiang, Chien-Wei,Lei, Aiwen
supporting information, p. 12206 - 12210 (2019/07/31)
The [4+2] annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible-light induced [4+2] annulation of thiophenes and alkynes, to afford benzene rings, is presented. Under simple and mild reaction conditions, the ready availability and structural diversity of thiophenes and alkynes permit the facile synthesis of several substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain the high regioselectivity of the reaction.
Nickel-Catalyzed Reductive Cleavage of Carbon-Oxygen Bonds in Anisole Derivatives Using Diisopropylaminoborane
Igarashi, Takuya,Haito, Akira,Chatani, Naoto,Tobisu, Mamoru
, p. 7475 - 7483 (2018/07/21)
The catalytic removal of a methoxy group on an aromatic ring allows this group to be used as a traceless activating and directing group for aromatic functionalization reactions. Although several catalytic methods for the reductive cleavage of anisole derivatives have been reported, all are applicable only to π-extended aryl ethers, such as naphthyl and biphenyl ethers, while monocyclic aryl ethers cannot be reduced. Herein, we report a nickel-catalyzed reductive cleavage reaction of C-O bonds in aryl ethers using diisopropylaminoborane as the reducing agent. Unlike previously reported methods, this reducing reagent allows effective C-O bond reduction in a much wider range of aryl ether substrates, including monocyclic and heterocyclic ethers bearing various functional groups.
Gold(I)-phosphine catalyst for the highly chemoselective dehydrogenative silylation of alcohols
Ito, Hajime,Takagi, Katsuhiro,Miyahara, Takahiro,Sawamura, Masaya
, p. 3001 - 3004 (2007/10/03)
(Chemical Equation Presented) A gold(I) complex of Xantphos AuCl(xantphos) catalyzes the dehydrogenative silylation of alcohols with high chemoselectivity and solvent tolerance. It is selective for the silylation of hydroxyl groups in the presence of alke
Solvent-modulated Pd/C-catalyzed deprotection of silyl ethers and chemoselective hydrogenation
Ikawa, Takashi,Hattori, Kazuyuki,Sajiki, Hironao,Hirota, Kosaku
, p. 6901 - 6911 (2007/10/03)
Recently we have reported undesirable and frequent deprotection of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. The deprotection of silyl ethers is susceptible to significant solvent effect. TBDMS and TES protecting groups were selectively cleaved in the presence of acid-sensitive functional groups such as TIPS ether, TBDPS ether and dimethyl acetal under hydrogenation condition using 10% Pd/C in MeOH. In contrast, chemoselective hydrogenation of reducible functional groups such as acetylene, olefin and benzyl ether, proceeds in the presence of TBDMS or TES ethers in AcOEt or MeCN.
Effective silylation of carboxylic acids under solvent-free conditions with tert-butyldimethylsilyl chloride (TBDMSCL) and triisopropylsilyl chloride (TIPSCL)
Firouzabadi, Habib,Iranpoor, Naser,Shaterian, Hamid Reza
, p. 71 - 81 (2007/10/03)
Varions types of carboxylic acids can be converted effectively to their corresponding TBDMS and TIPS esters using TBDMSCI and TIPSCI in the presence of imidazole under solvent-free conditions. The advantage of this modified method in comparison with that reported by Corey is the elimination of DMF, which eliminates aqueous work-up. The method is not a time-consuming process and the reactions proceed spontaneously. By this method, absolute chemoselectivity for the protection of carboxylic acid functions in the presence of 2°, 3° hydroxyl groups are observed.
Alkoxyallylsilanes: Functional protecting groups
Balduzzi, Sonya,Brook, Michael A.
, p. 1617 - 1622 (2007/10/03)
Allyl-t-butylmethylsilyl groups were shown to function as alcohol protecting groups whose hydrolytic stability was greater than t- butyldimethylsilyl (TBS) and Si(SiMe3)3 (sisyl) groups. Pseudo-first-order rate constants for the acid
The photolytic and hydrolytic lability of sisyl (Si(SiMe3)3) ethers, an alcohol protecting group
Brook,Balduzzi,Mohamed,Gottardo
, p. 10027 - 10040 (2007/10/03)
The tris(trimethylsilyl)silyl (sisyl) group is a photolabile protecting group for primary and secondary alcohols. Sisyl (tris(trimethylsilyl)silyl) ethers 2b-11b of a number of primary and secondary alcohols 2a-11a were prepared in yields ranging from 70-97%. The resulting silyl ethers were stable to aqueous bases, Grignard reagents and Wittig reagents as would be expected for bulky alkoxysilanes. They were also stable to selected fluoride salts including CsF. The sisyl ethers could be cleaved using photolysis at 254 nm in under 30 minutes to give the starting alcohols in yields ranging from 62-95%. The photolytic behaviour of sisyl ethers was examined in more detail using 2,3-dimethyl-1,3-butadiene as a silylene trap. The regiochemistry of the oligosilane fragmentation to silylenes was shown to be dependent upon the alkoxy group. The hydrolytic stability of three was compared with the analogous t-butyldimethylsilyl ethers. The relative stability of the two silyl groups can be altered by choice of solvent: in acetic acid/water the ease of hydrolysis followed the order ROSi(SiMe3)3 > ROSiMe2t-Bu; the inverse order was observed in CDCl3 using p-TsOH·H2O. Pseudo-first-order rate constants for the acidic hydrolysis of primary, benzylic, and secondary sisyl ether in AcOH/THF/H2O were determined to be 3.74 x 10-2 s-1, 1.94 x 10-2 s-1, and 1.30 x 10-2 s-1, respectively. The analogous rate constants for the TBS ethers were determined to be 6.04 x 10-3 s-1, 3.53 x 10-3 s-1, and 3.49 x 10-3 s-1, respectively.
A novel method for direct conversion of tetrahydropyranyl ethers into t-butyldimethylsilyl ethers with t-butyldimethylsilyl triflate and dimethyl sulfide
Kim,Kee
, p. 2899 - 2900 (2007/10/02)
Direct conversion of THP ethers into TBS ethers has been achieved with TBSOTf and dimethyl sulfide in dichloromethane.
Co2(CO)8 CATALYZED REACTIONS OF STYRENE OXIDE WITH TRIALKYLSILANES
Kang, Kyung-Tae,Weber, William P.
, p. 5415 - 5416 (2007/10/02)
The dicobalt octacarbonyl catalyzed reaction of styrene oxide with trialkylsilanes yields a mixture of 1-phenyl-2-trialkylsiloxyethane and Z- and E-1-phenyl-2-trialkylsiloxyethene.The ratio of these products can be controlled.
