1625-49-6

Upstream product

• 75-07-0 acetaldehyde 
• 565-62-8 3-methylpent-3-en-2-one 
• 74-88-4 methyl iodide 
• 1567-73-3 (E)-3-methylpent-3-en-2-one 
• 32596-24-0 1,2,3-trimethylcyclobutane 
• 19493-09-5 Methylenetriphenylphosphorane 
• 2065-66-9 methyl-triphenylphosphonium iodide 
• 53496-45-0 4-hydroxy-3-methyl-pentan-2-one 

Downstream Products

• 345930-78-1 3,4-dimethyl-1-nitro-1-(1-phenylpentyl)-3-cyclohexene 

Relevant academic research and scientific papers

Regio- and enantioselective linear cross-dimerizations between conjugated dienes and acrylates catalyzed by new Ru(0) complexes

New naphthalene complexes of Ru(0) with various Ru(π6-naphthalene)(cyclic diene) (3) ligands catalyze linear cross-dimerization between conjugated dienes and acrylates. One of the noteworthy catalysts is the dibenzocyclooctatetraene complex 3d,

Importance of the role of secondary orbital interactions in the Diels-Alder reaction. Regioselectivity in the catalyzed and uncatalyzed reactions of juglone and aliphatic dienes

The regioselectivities in the uncatalyzed and catalyzed Diels-Alder (DA) reactions of juglone with piperylene (penta-1,3-diene) or 2,3-dimethylpenta-1,3-diene have been investigated, employing Lewis acids such as boron trifluoride (BF3) and sterically hindered aluminium catalysts in order to verify the role of the secondary orbital interactions (SOI). While the results of the uncatalyzed and catalyzed reactions using BF3 or aluminium trimethoxide agree with the prediction made by the frontier molecular orbital (FMO) theory considering SOI, steric repulsion of the aluminium catalysts causes orderly changes to the ratios of the product regioisomers, which could be interpreted by diminution of SOI. The transition states are located by AM1 calculations and their energies are estimated by CDNO/2-CI and ab initio 6-31G* calculations. The regioselectivities observed in the experiments are explained by comparison of their energies. A zwitterionic mechanism in the catalyzed reaction was strongly supported and the molecular orbital feature suggests the contribution of SOI which would stabilize the transition state to control the reaction pathway.

Cyclobutene photochemistry. Steric effects on the photochemical ring opening of alkylcyclobutenes

Quantum yields for photochemical ring opening and cycloreversion in hydrocarbon solution have been determined for the direct photolysis (214 nm) of six 1,2-dimethylcyclobutene derivatives which contain methyl groups at C3, and C4 in numbers varying from zero to four. As the hydrogens on C3/C4 of the parent compound (1,2-dimethylcyclobutene) are replaced with increasing numbers of methyl groups, the total quantum yield for ring opening increases to a maximum of ～0.3 and then decreases with further methyl substitution. The quantum yields for ring opening (φtotal) of hexamethylcyclobutene and 1,2-dimethylcyclobutene are nearly the same, and the lowest in the series. The maximum occurs with trans-1,2,3,4-tetramethylcyclobutene; φtotal for the cis-isomer is significantly lower, but both yield an approximate 1:1 mixture of formally allowed and forbidden diene isomers. A similar trend is observed in the relative quantum yields for ring opening and cycloreversion throughout the series. The results are interpreted in terms of a combination of bond strength and steric effects on the efficiency of the ring-opening process. Increasing methyl substitution causes an increase in φtotal through the first three members of the series owing to progressive weakening of the C3-C4 bond. Compounds containing cis-dimethyl substitution exhibit substantially reduced quantum yields for ring opening, relative to what would be expected based on bond strength effects alone. This is proposed to be due to steric effects on the efficiency of the process, suggesting that the initial stages of the photochemical ring opening of cyclobutene involve disrotatory motions on the excited singlet state potential energy surface.

The Mechanism of 1,4-Addition of Dibromomethylene

Dibromomethylene produced from the Seyferth reagent (PhHgCBr3) may react as a free species or while complexed with Lewis bases.Recent reports of the long-sought 1,4-addition to dienes of dibromomethylene, produced from the Seyferth reagent, to form five-membered rings therefore could be based on reactions of either free or complexed carbenes.These modes of reaction may be distinguished by product ratio dependence on the diene concentration, on the solvent basicity, and on the basicity of additives.We have found that the addition of Seyferth-generated dibromomethylene to the exo dienes 1 and 2 gives a ratio of 1,2- and 1,4-addition that is independent of all these considerations of concentration, solvent, and additive.These observations lend strong support to the assertion that 1,4-addition occurs by a concerted, symmetry-allowed pathway.When the carbane source is 11,11-dibromo-1,6-methanoannulene, addition to 1,2-dimethylenecyclohexane (1) gives the same proportion of 1,4-addition as for the Seyferth reagent, indicating a free carbene in both cases.Addition of dibromomethylene from the annulene to the sterically congested 2, however, gives a much augmented proportion of 1,4-addition, in fact the major pathway of the first time.This observation may indicate a complexed carbene in this case.

Chemical process

Novel 2,4-dihydrocarbylspiro[5.5]undeca-1,4,8-trien-3-one compounds are prepared by reacting an N,N-dihydrocarbyl,2,6-dihydrocarbyl-4-aminomethylphenol with a conjugated diene and an alkyl halide in a liquid solvent medium.

Cycloadditions of Allyl Cations, 29. Acid Catalyzed Reactions of 2,3-Dimethyl-3-penten-2-ol and Cyclopentadiene in Two Phases. Formation of Seven- and Five-membered Rings

2,3-Dimethyl-3-penten-2-ol (3) and cyclopentadiene were stirred in dilute aqueous sulfonic acid/pentane, giving 2,3,4,4-tetramethylbicycloocta-2,6-diene (4), the epimeric 3-methylene isomers 5a, b and, for the first time, also a five-membered ring, namely 2,3,4,4-tetramethylbicycloocta-2,6-diene (6) in 69 - 73percent overall yield.The major bicyclic diene 4 was conveniently isolated as crystalline silver nitrate complex (C12H18)2*AgNO3 (41 - 44percent).In a modified approach the two phase reaction was carried out at 0 deg C, the resulting alcohols were separated by chromatography and cyclized at 50 deg C, giving an increased proportio n of the thermodynamically more stable, novel bicyclic isomer 6 (4 : 6 = 2.6 : 1).