15051-90-8Relevant articles and documents
Benzoxaborole Catalyst for Site-Selective Modification of Polyols
Kusano, Shuhei,Miyamoto, Shoto,Matsuoka, Aki,Yamada, Yuji,Ishikawa, Ryuta,Hayashida, Osamu
supporting information, p. 1598 - 1602 (2020/02/11)
The site-selective modification of polyols bearing several hydroxyl groups without the use of protecting groups remains a significant challenge in synthetic chemistry. To address this problem, novel benzoxaborole derivatives were designed as efficient catalysts for the highly site-selective and protecting-group-free modification of polyols. To identify the effective substituent groups enhancing the catalytic activity and selectivity, a series of benzoxaborole catalysts 1a–k were synthesized. In-depth analysis for the substituent effect revealed that 1i–k, bearing multiple electron-withdrawing fluoro- and trifluoromethyl groups, exhibited the greatest catalytic activity and selectivity. Moreover, 1i-catalyzed benzoylation, tosylation, benzylation, and glycosylation of various cis-1,2-diol derivatives proceeded with good yield and site-selective manner.
Chiral benzazaboroles as catalysts for enantioselective sulfonylation of: Cis -1,2-diols
Kuwano, Satoru,Hosaka, Yusei,Arai, Takayoshi
supporting information, p. 4475 - 4482 (2019/05/16)
A newly developed benzazaborole smoothly catalyzed the enantioselective sulfonylation of cis-1,2-diols. Using a chiral benzazaborole/NMI co-catalyst system, various sulfonate esters were prepared in high yields with good enantioselectivities.
Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: Expansion of substrate scope and mechanistic studies
Lee, Doris,Williamson, Caitlin L.,Chan, Lina,Taylor, Mark S.
supporting information; experimental part, p. 8260 - 8267 (2012/07/14)
Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
Bronsted acid-catalyzed dihydroxylation of olefins in aqueous medium
Rosatella, Andreia A.,Afonso, Carlos A.M.
supporting information; experimental part, p. 2920 - 2926 (2012/01/03)
The trans-dihydroxylation of olefins occurs efficiently by aqueous hydrogen peroxide catalyzed by p-toluenesulfonic acid at 50°C, allowing the catalyst reuse and an outstanding substrate functional group tolerance such as tert-butoxycarbonylamino (BocNH), benzyloxycarbonylamino (CbzNH), benzyloxy (OBn), tosyloxy (OTs), hindered ketal, (2-trimethylsilyl)ethoxymethoxy (OSEM), benzylamino (NBz), benzyloxy (OBz) and free amino acid. Copyright
Catalytic regioselective sulfonylation of α-chelatable alcohols: Scope and mechanistic insight
Martinelli, Michael J.,Vaidyanathan, Rajappa,Pawlak, Joseph M.,Nayyar, Naresh K.,Dhokte, Ulhas P.,Doecke, Christopher W.,Zollars, Lisa M. H.,Moher, Eric D.,Khau, Vien Van,Kosmrlj, Berta
, p. 3578 - 3585 (2007/10/03)
This paper describes a convenient protocol for the regioselective sulfonylation of α-chelatable alcohols. Typically, the reaction of α-heterosubstituted alcohols with 1 equiv of p-TsCl and 1 equiv of Et3N in the presence of 2 mol % of Bu2SnO leads to rapid, regioselective, and exclusive monotosylation. The pKa of the amine was correlated to the reaction rate. A plausible mechanism for this reaction has been proposed on the basis of 119Sn NMR studies.
Selective monosulfonylation of internal 1,2-diols catalyzed by di-n- butyltin oxide
Martinelli, Michael J.,Vaidyanathan, Rajappa,Van Khau, Vien
, p. 3773 - 3776 (2007/10/03)
The reaction of internal 1,2-diols with catalytic n-Bu2SnO, p-TsCl (1.05 equiv.) and Et3N (1.1 equiv.) led to selective monotosylation. In the case of cyclic substrates, the cis-1,2-diol moiety appeared best suited for optimal results, supporting the intermediacy of a five-membered chelate. (C) 2000 Elsevier Science Ltd.
Selective Sulfonylating Agents
Guthrie, R. D. (Gus),Thang, San
, p. 2133 - 2136 (2007/10/02)
A variety of bulky sulfonyl chlorides have been investigated as sulfonylating reagents for polyol systems in an endeavour to find a selective reagent that would also give rise to a reactive sulfonate ester group.
NUCLEOPHILIC CHARACTERISTICS OF NUCLEOFUGIC ANIONS IN THE CLEAVAGE OF EPOXIDES BY PROTIC ACIDS AND NITRONIUM FLUOROBORATE
Zefirov, N. S.,Kirin, V. N.,Yur'eva, N. M.,Zhdankin, V. V.,Kozmin, A. S.
, p. 1264 - 1279 (2007/10/02)
The cleavage of ethylene, propylene, and cyclohexene oxides by protic acids RCOOH (R= CH3, CF3) in the presence of sources of nucleophilic anions (the lithium or tetrabutylammonium salts of perchloric or substituted sulfonic acids) leads to the formation not only of 2-hydroxyalkyl carboxylates but also of significant amounts of 2-hydroxyalkyl perchlorates and sulfonates.In the reactions of the same oxides with nitronium fluoroborate and the above-mentioned salts in methylene chloride 2-perchloryl- and 2-sulfonyloxyalkyl nitrates are formed with high yields; these are the products from opening of the epoxide ring and subsequent combination of the perchlorate and substituted sulfonate ions.The investigated processes extend the range of reactions involving the concurrent combination of nucleofugic anions and can be used as a method for the production of β-hydroxy- and β-nitroxyalkyl perchlorates and sulfonates.
Reaction Manifolds of Alkenes with benzene: Stereospecific syn-1,2-Ditosyloxylation of the Carbon-Carbon Double Bond and Other Processes
Rebrovic, Louis,Koser, Gerald F.
, p. 2462 - 2472 (2007/10/02)
The treatment of various alkenes with benzene (1) in CH2Cl2 gives moderate yields of the corresponding vic-bis(tosyloxy)alkanes (2).When cis- and trans-2-butenes, cis- and trans-2-pentenes, cis-3-hexene, cis-4-octene, and cyclohexene are reactants, the tosyloxy ligands are introduced with syn stereospecifity.With cis- and trans-stilbenes, however, a mixture of meso- and dl-1,2-diphenyl-1,2-bis(tosyloxy)ethanes results from either alkene.Some alkenes react with 1 in a different way.Thus, trans-3-hexene and trans-4-octene with 1 give low yields of 2,5-bis(tosyloxy)-3-hexene and 3,6-bis(tosyloxy)-4-octene, respectively.Evidence is presented that the formation of the bis(tosyloxy)alkenes proceeds via initial oxidation of the trans alkenes by 1 to conjugated dienes and subsequent conjugate ditosyloxylation of the dienes.In a few cases, molecular rearrangements occur.Thus, norbornene with 1 gives 2,7-bis(tosyloxy)norbornane, among other products, while 1,1-diphenylethylene gives deoxybenzoin (major product) and (β,β-diphenylethenyl)phenyliodonium tosylate.The reaction of styrene with 1 depends on the medium; when CH2Cl2 is present, the product is 1-phenyl-1,2-bis(tosyloxy)ethane, but in the absence of solvent, the product is 1,1-bis(tosyloxy)-2-phenylethane.Most alkenes react with 1 to give p-toluenesulfonic acid as a byproduct, and, in rare instances, (iodoxy)benzene is obtained.A mechanism for the vic-ditosyloxylation of alkenes by 1, consistent with the observed syn stereospecificity, is proposed.
