نتایج جستجو برای: ene reaction
تعداد نتایج: 416165 فیلتر نتایج به سال:
The formation of 1 out of 64 stereoisomers, i.e. controlling the creation of 6 stereocenters, of important optically active bicyclo[3.3.1]non-2-ene compounds, has been achieved using organocatalysis; the reaction proceeds with excellent stereocontrol and can be carried out with the generation of enantiopure products using chromatography-free procedures.
Intramolecular carbonyl ene reactions of highly activated enophiles can be catalysed by H-bonding thio-ureas to give tertiary alcohols in high yields without extensive isomerisation side products. An asymmetric variant of this reaction was realised using a chiral thiourea but was limited by low enantioselectivity (up to 33% e.e.) and low turnover frequencies.
The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accompli...
Supercritical carbon dioxide can be employed as an environmentally friendly alternative to conventional organic solvents for the synthesis of a variety of carboxylic amides. The addition of amines to ketenes generated in situ via the retro-ene reaction of alkynyl ethers provides amides in good yield, in many cases with ethylene or isobutylene as the only byproducts of the reaction. Reactions wi...
The total synthesis of (+)-asteriscanolide starting from two commercially available materials has been accomplished in 19 steps with a 3.8% overall yield. The key reaction is a chiral ene-vinylcyclopropane substrate induced Rh(I)-catalyzed [(5+2)+1] cycloaddition that efficiently constructs the [6.3.0] carbocyclic core with complete asymmetric induction.
Enyne alcohols can react as precursors of either dienes or dienophiles with different substrates after hydroxylation and isomerization by gold catalysis. As such, oxa-bridged tricyclo[5.2.2.02,6]-undec-8-ene-3,5-dione derivatives have been obtained by the Diels–Alder reaction and tetrahydro-1H-furo[3,4-c]pyran derivatives could be accessed by the hetero-Diels–Alder cycloaddition.
The title compound, C(16)H(16)Cl(2)N(2), was synthesized by the condensation reaction between 4,5-dichloro-o-phenyl-ene-diamine and (1R)-(-)-camphorquinone in boiling acetic acid. The two crystallographically independent mol-ecules in the unit cell are related by a pseudo-inversion center.
The synthesis of (-)-Indolizidine 167B has been achieved from optically active (R)-3-(pyrrol-1-yl)hex-1-ene. The key step is a highly regioselective hydroformylation reaction and a one-pot intramolecular cyclization providing a general approach to the indolizine nucleus.
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