127708-33-2

Upstream product

• 930-68-7 cyclohexenone 
• 542-92-7 cyclopenta-1,3-diene 
• 152668-34-3 Methyl cis-6-chloro-2-hexenoate 
• 51804-12-7 Methyl 6-chloro-2-hexynoate 

Downstream Products

• 1236179-64-8 2-oxapentacyclo[6.4.0.0(1,4).0(3,7).0(5,9)]dodecane 

Relevant academic research and scientific papers

Chiral oxazaborolidine - Aluminum bromide complexes are unusually powerful and effective catalysts for enantioselective Diels - Alder reactions

Treatment of the chiral oxazaborolidine 1 with AlBr3 generates the 1:1 complex 3, which is an even more potent Lewis acid catalyst than protonated 1 (i.e., 2) for enantioselective Diels-Alder reactions. Only 4 mol % of catalyst 3 is required to achieve yields and enantiomeric purities of 90% over a broad range of achiral dienes and dienophiles. The ligand from which 3 is derived can be recovered easily and with high efficiency. The method is illustrated by 22 examples. Copyright

Silylium ion-catalyzed challenging Diels-Alder reactions: The danger of hidden proton catalysis with strong Lewis acids

The pronounced Lewis acidity of tricoordinate silicon cations brings about unusual reactivity in Lewis acid catalysis. The downside of catalysis with strong Lewis acids is, though, that these do have the potential to mediate the formation of protons by various mechanisms, and the thus released Bronsted acid might even outcompete the Lewis acid as the true catalyst. That is an often ignored point. One way of eliminating a hidden proton-catalyzed pathway is to add a proton scavenger. The low-temperature Diels-Alder reactions catalyzed by our ferrocene-stabilized silicon cation are such a case where the possibility of proton catalysis must be meticulously examined. Addition of the common hindered base 2,6-di-tert-butylpyridine resulted, however, in slow decomposition along with formation of the corresponding pyridinium ion. Quantitative deprotonation of the silicon cation was observed with more basic (Mes)3P to yield the phosphonium ion. A deuterium-labeling experiment verified that the proton is abstracted from the ferrocene backbone. A reasonable mechanism of the proton formation is proposed on the basis of quantum-chemical calculations. This is, admittedly, a particular case but suggests that the use of proton scavengers must be carefully scrutinized, as proton formation might be provoked rather than prevented. Proton-catalyzed Diels-Alder reactions are not well-documented in the literature, and a representative survey employing TfOH is included here. The outcome of these catalyses is compared with our silylium ion-catalyzed Diels-Alder reactions, thereby clearly corroborating that hidden Bronsted acid catalysis is not operating with our Lewis acid. Several simple-looking but challenging Diels-Alder reactions with exceptionally rare dienophile/enophile combinations are reported. Another indication is obtained from the chemoselectivity of the catalyses. The silylium ion-catalyzed Diels-Alder reaction is general with regard to the oxidation level of the α,β-unsaturated dienophile (carbonyl and carboxyl), whereas proton catalysis is limited to carbonyl compounds.

Experimental Diels-Alder reactivities of cycloalkenones and cyclic dienes explained through transition-state distortion energies

Quantum chemical calculations are used to investigate the experimentally measured reactivities of cyclic dienes and cycloalkenones in the Diels-Alder reaction. The interaction energies (red) are nearly constant; differences arise in changes in distortion energies of both dienophile (blue) and diene (green; see picture, Ea=activation energy; values in kcal mol-1). Copyright

Strained to the limit: When a cyclobutyl moiety becomes a thermodynamic sink in a protolytic ring-opening of photogenerated oxetanes

(Equation Presented). Strained polycyclic oxetanes generated photochemically from the Diels-Alder adducts of cyclic dienes and enones undergo deep skeletal rearrangements under protolytic ring-opening conditions offering expeditious access to chlorohydrins and other products of unique skeletal topology.

Intramolecular Nucleophilic Acyl Substitution Reactions of Halo-Substituted Esters and Lactones. New Applications of Organosamarium Reagents

Intramolecular nucleophilic acyl substitution reactions involving a broad range of halo substituted carboxylic acid derivatives have been accomplished in excellent yield employing samarium(II) iodide as the reductive coupling agent.Although particular substrates cyclized most effectively in THF in the presence of tripiperidinophosphine oxide, carboxylic acid esters, the focus of this report, cyclize equally well without such an additive in the presence of a catalytic quantity of iron(III) complexes.Thus a comprehensive series of halo substituted esters were cyclized in excellent yield to the corresponding 4-, 5-, and 6 -membered carbocycles.The reaction is extremely mild and selective as demonstrated by experiments wherein alkyl chlorides, acetals, and olefins remain completely intact under the reaction conditions.In addition to introducing a convenient procedure for preparing stereodefined spirocyclic systems, a new ring expansion sequence has been developed that appears extremely general for the preparation of various ring systems.

Effect of micellar medium on photoannelation vs energy transfer in the system excited cyclohex-2-en-1-one-cyclopentadiene

The relative ratio of enone-CPD adducts and C15H18 formed in the photochemical reaction between cyclohex-2-en-1-one and its 4,4 dimethyl derivative and CPD in different media suggest that an exciplex is responsible for 2+2 photoannelation and energy transfer and a transoid or twisted enone for photo Diels-Alder reaction.

Diels-Alder Reactions of Cycloalkenones. 14. Endo Diastereoselectivity of 2-Cyclohexenones in Reactions with Cyclopentadiene

Aluminium chloride catalyzed Diels-Alder reactions of 2-cyclohexenones with cyclopentadiene are described.Structure analysis of the adducts by standard means and 13C NMR spectroscopy is presented.The endo-exo diastereoselectivity of the above and earlier reactions is discussed.