1886-71-1Relevant academic research and scientific papers
Dibutyltin oxide catalyzed selective sulfonylation of α-chelatable primary alcohols
Martinelli, Michael J.,Nayyar, Naresh K.,Moher, Eric D.,Dhokte, Ulhas P.,Pawlak, Joseph M.,Vaidyanathan, Rajappa
, p. 447 - 450 (2008/02/11)
(equation presented) The reaction of substituted glycols with catalytic dibutyltin oxide, stoichiometric p-toluenesulfonyl chloride, and triethylamine in CH2Cl2 resulted in the complete and rapid sulfonylation at the primary alcohol. The α-heterosubstituted primary alcohol moiety appeared optimal for best results, supporting the intermediacy of a five-membered chelate. The role of the amine is discussed, in addition to catalyst requirements and solvent effects.
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.
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.
Functionalization of Alkenes and Alkynes with benzene. Bis(tosyloxy)alkanes, Vinylaryliodonium Tosylates, and Alkynylaryliodonium Tosylates
Koser, Gerald F.,Rebrovic, Louis,Wettach, Richard H.
, p. 4324 - 4326 (2007/10/02)
benzene (1) reacts with various alkenes to give bis(tosyloxy)alkanes and with various alkynes to give either vinylaryliodoniumtosylates or alkynylaryliodonium tosylates.In the presence of 1, 1,1-diphenylethylene undergoes oxidative rearrangement and phenyliodination.
