23850-78-4Relevant academic research and scientific papers
Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
Lambert, Tristan H.,Steiniger, Keri A.
supporting information, p. 8013 - 8017 (2021/10/25)
The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
Intermolecular sp3-C-H Amination for the Synthesis of Saturated Azacycles
Betz, Kerry N.,Chiappini, Nicholas D.,Du Bois
supporting information, p. 1687 - 1691 (2020/01/09)
The preparation of substituted azetidines and larger ring, nitrogen-containing saturated heterocycles is enabled through efficient and selective intermolecular sp3-C-H amination of alkyl bromide derivatives. A range of substrates are demonstrated to undergo C-H amination and subsequent sulfamate alkylation in good to excellent yield. N-Phenoxysulfonyl-protected products can be unmasked under neutral or mild basic conditions to yield the corresponding cyclic secondary amines. The preparative convenience of this protocol is demonstrated through gram-scale and telescoped multistep procedures. Application of this technology is highlighted in a nine-step total synthesis of an unusual azetidine-containing natural product, penaresidin B.
Vinylidene Homologation of Boronic Esters and its Application to the Synthesis of the Proposed Structure of Machillene
Fordham, James M.,Grayson, Matthew N.,Aggarwal, Varinder K.
supporting information, p. 15268 - 15272 (2019/10/21)
Alkenyl boronic esters are important reagents in organic synthesis. Herein, we report that these valuable products can be accessed by the homologation of boronic esters with lithiated epoxysilanes. Aliphatic and electron-rich aromatic boronic esters provided vinylidene boronic esters in moderate to high yields, while electron-deficient aromatic and vinyl boronic esters were found to give the corresponding vinyl silane products. Through DFT calculations, this divergence in mechanistic pathway has been rationalized by considering the stabilization of negative charge in the C?Si and C?B bond breaking transition states. This vinylidene homologation was used in a short six-step stereoselective synthesis of the proposed structure of machillene, however, synthetic and reported data were found to be inconsistent.
Efficient and convenient epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6]
Hu, Yu-Lin,Liu, Yi-Wen,Li, De-Jiang
, p. 2179 - 2184 (2015/10/19)
A simple, efficient, and eco-friendly procedure for the epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6] has been developed. The reactions were carried out with alkene, Co(OAc)2 (0.1 mmol), [C12py][PF6] (10 mL), and H2O2 (30 %, 11 mmol) at room temperature for 2-6 h. This atom-economical protocol affords the target products in good to high yields (88-98 %). The products can be separated by a simple extraction with organic solvent, and the catalytic system can be recycled and reused without loss of catalytic activity. Graphical abstract: A simple, efficient, and eco-friendly procedure for the epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6] has been developed.[Figure not available: see fulltext.]
Regioselectivity and diasteroselectivity in Pt(II)-mediated "green" catalytic epoxidation of terminal alkenes with hydrogen peroxide: Mechanistic insight into a peculiar substrate selectivity
Colladon, Marco,Scarso, Alessandro,Sgarbossa, Paolo,Michelin, Rino A.,Strukul, Giorgio
, p. 7680 - 7689 (2008/02/05)
Recently developed electron-poor Pt(II) catalyst 1 with the "green" oxidant 35% hydrogen peroxide displays high activity and complete substrate selectivity in the epoxidation of terminal alkenes because of stringent steric and electronic requirements. In the presence of isolated dienes bearing terminal and internal double bonds, epoxidation is completely regioselective toward the production of terminal epoxides. Insight into the mechanism is gained by means of a reaction progress kinetic analysis approach that underlines the peculiar role of 1 in activating both the alkene and H 2O2 in the rate-determining step providing a rare example of nucleophilic oxidation of alkenes by H2O2.
Synthesis and Insecticidal Activity of Oxazaphospholidines, Oxathiaphospholanes, and Thiazaphospholidines
Wu, Shao-Yong,Hirashima, Akinori,Takeya, Ryuko,Eto, Morifusa
, p. 2911 - 2918 (2007/10/02)
Fifty-five new five-membered cyclic organophosphorus compounds including oazaphospholidines, thiazaphospholidines, and oxathiaphospholanes were synthesized, which have substituents at 4- or/and 5-positions besides at the 2-position.The thiazaphospholidines showed the highest insecticidal activity followed by oxathiaphospholanes and oxazaphospholidines.The position preference of substituents in insecticidal activity was most obvious in the oxazaphospholidines.It was preferable for insecticidal activity to have the substituent near the more basic atom: the 4-position for thiazaphospholidine and oxazaphospholidine, the 5-position for oxathiaphospholane, with the exception of 4- or 5-phenyl oxazaphospholidine.
Dissociations of Positively Charged Aliphatic Epoxides. I. Structure Elucidation of the η-Cleavage Products
Bouchoux, Guy,Hoppilliard, Yannik,Jaudon, Pascale
, p. 98 - 102 (2007/10/02)
Dissociative ionization of 1,2-epoxy n-alkanes gives rise to abundant + ions of structure +.This conclusions is drawn from metastable ion analysis and from collosional activation spectra.This fragmentation involves the C-C ring opening and a 1,4-H migration leading to the corresponding enol ether +. precursor of + fragment.The same isomerization scheme applies to 1,2-epoxy methyl substituted alkanes and 2,3-epoxy n-alkanes.
THE SYNTHETIC UTILITY OF DIOXYPHOSPHORANES IN ORGANIC SYNTHESIS
Robinson, Philip L.,Kelly, Jeffery W.,Evans, Slayton A.
, p. 15 - 24 (2007/10/02)
Diethoxytriphenylphosphorane, DTPP, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild and efficient cyclodehydration of diols to cyclic ethers in neutral media.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively, with DTPP.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes in the presence of DTPP and the reaction conditions dictate whether epoxides, ketones, or allylic alcohols are obtained.
Diethoxytriphenylphosphorane: A Mild, Regioselective Cyclodehydrating Reagent for Conversion of Diols to Cyclic Ethers. Stereochemistry, Synthetic Utility, and Scope
Robinson, Philip L.,Barry, Carey N.,Kelly, Jeffery W.,Evans, Slayton A.
, p. 5210 - 5219 (2007/10/02)
Diethoxytriphenylphosphorane, Ph3P(OEt)2, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild cyclodehydration (40-110 deg C) of diols to cyclic ethers in neutral media.The regioselectivity in the closure of (S)-(+)-propane-1,2-diol and (R)-(-)-pentane-1,4-diol with Ph3P(OEt)2 is high (81-82 percent) while the cyclodehydration of (S)-(+)-phenylethane-1,2-diol gives racemized (+/-)-styrene oxide.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively with Ph3P(OEt)2.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes (or ?-dioxyphosphoranes) in the presence of Ph3P(OEt)2, and, depending on conditions, the 1,3,2-dioxaphospholanes are selectively converted to epoxides, ketones or allylic alcohols.The carbonyl compounds arise from 1,2-hydride and 1,2-methyl migrations; the allylic alcohols are derived from thermolytic eliminations. trans-1,2-Cyclohexanediols afford essentially quantitative yields (>95 percent) of the cyclohexene oxides while cis-1,2-cyclohexanediol gives the stable 1,3,2-dioxaphospholane with Ph3P(OEt)2 which decomposes under thermal conditions to cyclohexanone (90 percent).Ph3P(OEt)2 is extremely useful for conversion of "sensitive" 1,2-diols to acidic and /or thermally labile epoxides as demonstrated by the quantitative conversion of 9,10-dihydro-trans-9,10-phenanthrenediol to 9,10-dihydrophenanthrene oxide and 2α,10-pinanediol to 2α,10-epoxypinane.
Cyclodehydration and Chlorination of Simple Diols with Triphenylphosphine and tert-Butyl Hypochlorite
Barry, Carey N.,Evans, Slayton A.
, p. 2825 - 2828 (2007/10/02)
The reagent triphenylphosphine-tert-butyl hypochlorite converts 1,4-diols into the corresponding tetrahydrofurans and 1,2-diols into a mixture of the regioisomeric chlorohydrins and the epoxides at -78 deg C followed by warming to ambient temperature (ca. 30 deg C).Symmetrical diols give largely chlorohydrins and dichlorides.
