21856-89-3Relevant articles and documents
Identification and optimization of novel pyrimido-isoxazolidine and oxazine as selective hydride donors
Khan, Imran A.,Balaramnavar, Vishal M.,Saxena, Anil K.
, p. 10122 - 10129,8 (2012)
Two novel carbon skeletons (3S,3a′R)-6′-(methylthio)-5′, 7a′-dihydro-1′H-spiro[indoline-3,3′-isoxazolo[3,4-d] pyrimidine]-2,4′(3a′H)-dione (11a) and 3-(methylthio)-4a,5,7,11c- tetrahydropyrimido[4′,5′:3,4][1,2]oxazino[6,5-b]indol-1(2H)-one (12a) are characterized as hydride donors. The generation of these hydride sources during the spiroannulation reaction between isatin (4) and pyrimidine (5) through the free radical mechanism, was confirmed by (i) the increase in the stoichiometric yields of 11 and 12 when the same reaction was carried out in the presence of free radical initiators (e.g., mCPBA) and (ii) the formation of oxazepine (14) when AIBN was used as free radical initiator. The PKIE [K H/KD] values 4.5 and 4.9 obtained when deuterated 11a (d) was used in the presence of TFA and TFA-d, respectively, suggest the hydride transfer step to be the rate determining step. These hydrides donors selectively reduce aldehyde in the presence of other reducible groups.
Sime3-based homologation-epoxidation-cyclization strategy for ladder THP synthesis
Heffron, Timothy P.,Jamison, Timothy F.
, p. 2339 - 2342 (2003)
(Matrix presented) A trimethylsilyl (SiMe3) group is the basis of a strategy that emulates the three fundamental proposed processes in ladder polyether biosynthesis: chain homologation, stereoselective epoxidation (>95% ee or >95:5 dr), and endo-selective, stereospecific (inversion) hydroxyepoxide cyclization (>95:5 endo:exo, >95% dr). A tris-THP was synthesized in 18 total operations from commercial materials using this approach.
Expansion of substrate scope for nitroxyl radical/copper-catalyzed aerobic oxidation of primary alcohols: A guideline for catalyst selection
Iwabuchi, Yoshiharu,Nagasawa, Shota,Sasaki, Ryota,Sasano, Yusuke,Yamaichi, Aoto
, p. 488 - 497 (2021/05/27)
Four distinctive sets of optimum nitroxyl radical/copper salt/additive catalyst combinations have been identified for accommodating the aerobic oxidation of various types of primary alcohols to their corresponding aldehydes. Interestingly, less nucleophilic catalysts exhibited higher catalytic activities for the oxidation of particular primary allylic and propargylic alcohols to give α,β-unsaturated aldehydes that function as competent Michael acceptors. The optimum conditions identified herein were successful in the oxidation of various types of primary alcohols, including unprotected amino alcohols and divalent-sulfur-containing alcohols in good-to-high yields. Moreover, N-protected alaninol, an inefficient substrate in the nitroxyl radical/ copper-catalyzed aerobic oxidation, was oxidized in good yield. On the basis of the optimization results, a guideline for catalyst selection has been established.
Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
, p. 782 - 792 (2019/01/03)
Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
Revisiting Sodium Hypochlorite Pentahydrate (NaOCl·5H 2 O) for the Oxidation of Alcohols in Acetonitrile without Nitroxyl Radicals
Hirashita, Tsunehisa,Sugihara, Yuto,Ishikawa, Shota,Naito, Yohei,Matsukawa, Yuta,Araki, Shuki
, p. 2404 - 2407 (2018/11/23)
Sodium hypochlorite pentahydrate (NaOCl·5H 2 O) is capable of oxidizing alcohols in acetonitrile at 20 °C without the use of catalysts. The oxidation is selective to allylic, benzylic, and secondary alcohols. Aliphatic primary alcohols are not oxidized.
