191112-45-5Relevant academic research and scientific papers
Enantioselective synthesis of allenes by catalytic traceless petasis reactions
Jiang, Yao,Diagne, Abdallah B.,Thomson, Regan J.,Schaus, Scott E.
supporting information, p. 1998 - 2005 (2017/02/15)
Allenes are useful functional groups in synthesis as a result of their inherent chemical properties and established reactivity patterns. One property of chemical bonding renders 1,3-substituted allenes chiral, making them attractive targets for asymmetric synthesis. While there are many enantioselective methods to synthesize chiral allenes from chiral starting materials, fewer methods exist to directly synthesize enantioenriched chiral allenes from achiral precursors. We report here an asymmetric boronate addition to sulfonyl hydrazones catalyzed by chiral biphenols to access enantioenriched allenes in a traceless Petasis reaction. The resulting Mannich product from nucleophilic addition eliminates sulfinic acid, yielding a propargylic diazene that performs an alkyne walk to afford the allene. Two enantioselective approaches have been developed; alkynyl boronates add to glycolaldehyde imine to afford allylic hydroxyl allenes, and allyl boronates add to alkynyl imines to form 1,3-alkenyl allenes. In both cases, the products are obtained in high yields and enantioselectivities.
Ru- and Pd-catalysed synthesis of 2-arylfurans by one-flask heck arylation/oxidation
Schmidt, Bernd,Geissler, Diana
supporting information; experimental part, p. 4814 - 4822 (2011/10/09)
2,5-Disubstituted furans were synthesized by one-flask Heck arylation/oxidation sequences. The starting materials are 2-substituted 2,3-dihydrofurans, conveniently available by RCM/isomerization sequences, and arenediazonium salts. These react in ligand-free Heck reactions to afford 2,5-disubstituted 2,5-dihydrofurans, which are oxidized to the corresponding furans without isolation or intermediate workup. The oxidation is conveniently achieved with chloranil or DDQ, depending on the substrate.
An olefin metathesis/double bond isomerization sequence catalyzed by an in situ generated ruthenium hydride species
Schmidt, Bernd
, p. 816 - 819 (2007/10/03)
The direct conversion of allyl ethers to cyclic enol ethers using an olefin metathesis/double bond migration sequence is described. Ruthenium carbene complexes were activated to catalyze the double bond migration step by addition of hydride sources, such
Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(I)-mediated reactions with dicyclohexylcarbodiimide
Duffy, Michael G.,Grayson, David H.
, p. 1555 - 1563 (2007/10/03)
(Z)-1,4-dihydroxyalk-2-enes were converted into 2,5-dihydrofurans and alkane-1,4-diols were converted into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas. The reaction involved protonation of the carbodiimide by acidic phenol followed by reaction with alkanol. Pd/CaCo3-quinoline catalyst system was employed in the presence of a little triethylamine to overcome partial hydrogenolysis.
