63776-27-2

Upstream product

• 5407-91-0 1,4-diphenylbutan-1-one 
• 16282-16-9 1,2-diphenyl-butan-1-one 
• 42436-86-2 2-phenylcyclobutanone 
• 98-80-6 phenylboronic acid 

Downstream Products

• 5407-91-0 1,4-diphenylbutan-1-one 
• 1432045-45-8 1,2-diphenyl-6-(triisopropylsilyl)hex-5-yn-1-one 
• 865113-51-5 4-azido-1,4-diphenyl-butan-1-one 

Relevant academic research and scientific papers

Manganese-catalyzed oxidative azidation of cyclobutanols: Regiospecific synthesis of alkyl azides by C-C bond cleavage

A novel, manganese-catalyzed oxidative azidation of cyclobutanols is described. A wide range of primary, secondary, and tertiary alkyl azides were generated in synthetically useful yields and exclusive regioselectivity. Aside from linear alkyl azides, oth

Intramolecular O-H...O hydrogen-bond-mediated reversal in the partitioning of conformationally restricted triplet 1,4-biradicals and amplification of diastereodifferentiation in their lifetimes

The photoreactivity and nanosecond transient phenomena have been investigated for a rationally designed set of ketones 4-9 in order to gain comprehensive insights concerning the influence of intramolecular hydrogen bonding on (i) the lifetimes of triplet 1,4-biradicals and (ii) the partitioning of the latter between cyclization and elimination. Comparisons of the photochemical results and lifetime data for the biradicals of ketones 6 versus 8 and 7 versus 9 revealed a remarkable influence of hydrogen bonding when superimposed upon steric factors: while 6 and 7 yielded cyclobutanols in poor yields, cyclization was found to be overwhelmingly predominant for 8-anti and moderately so for 9-anti, with a high stereoselectivity in the formation of cyclobutanols (>95% for 8-anti). The diastereochemistry in the case of 8 permitted the occurrence of fragmentation or cyclization almost exclusively (>90% cyclization for 8-anti and >75% elimination for 8-syn). Significantly, the intramolecular hydrogen bonding in the biradicals of 8 and 9 was found to reverse their partitioning between cyclization and elimination compared with the behavior of the biradicals of ketones 3; the ketones 8-anti and 9-anti underwent cyclization in benzene, predominantly leading to cyclobutanols with syn stereochemistry between the C2 and C3 substituents. In accordance with photoproduct profiles, an unprecedented ～2-fold difference in the lifetimes of the intermediate diastereomeric triplet biradicals of ketones 8 in nonpolar solvents (e.g., τsyn = 123 ns and τanti = 235 ns in cyclohexane) was observed via nanosecond laser flash photolysis, while no such difference in lifetimes was found for the triplet biradicals of acetoxy ketones 9. The intriguing diastereodifferentiation in the lifetimes of the diastereomeric triplet 1,4-biradicals of 8 and the product profiles of ketones 6, 7, and 9 are best reconciled via a unified mechanistic picture in which superposition of steric factors over varying magnitudes of O-H...O hydrogen bonding selectively facilitates a particular pathway. In particular, the diastereodifferentiation in the photochemical outcomes for the diastereomers of ketone 8 and in the lifetimes of their triplet biradicals can be understood on the basis of rapid deactivation of the 8-syn triplet biradical via fragmentation and slow cyclization of the 8-anti triplet biradical from chair- and twist-boat-like hydrogen-bonded conformations, respectively. The photolysis in polar aprotic solvents such as DMSO and pyridine was found to reverse the chemoselectivity, yielding reactivity paralleling that of ketones 3, for which the steric factors between the C2 and C3 substituents control the photochemical outcome.

Addition/ring-opening reaction of organoboronic acids to cyclobutanones catalyzed by rhodium(I)/P(t-Bu)3 complex

An addition/ring-opening reaction of aryl- and alkenylboronic acids to cyclobutanones took place in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine, affording ring-opened ketones. Mechanistically, the reaction proceeded through the addition of an organorhodium species to the carbonyl group of a cyclobutanone and a subsequent ring-opening of the resulting rhodium cyclobutanolate through β-carbon elimination. A deuterium-labeling experiment revealed that an alkylrhodium species generated by the β-carbon elimination underwent successive β-hydride elimination/re-addition processes to form the η3-oxaallylrhodium intermediate, which was readily protonated to afford the product.

Base-catalysed Ring Opening of 1,2-Diphenylcyclobutanols

Cis- and trans-1,2-diphenylcyclobutanol have been prepared by literature methods and structural assignment confirmed by an X-ray crystal structure determination of the cis isomer.In the crystal structure, the four-membered ring has a pucker angle of 29 deg and the hydroxy group is pseudoequatorial with respect to the puckered ring.In aqueous base, both isomers rearrange to 1,4-diphenylbutan-1-one.Rates of this reaction in buffered aqueous dioxane have been measured.The isomers are almost equally reactive, kcis/ktrans ca. 0.7 at 25 deg C, although empirical force field calculations suggest that the cis isomer is more strained by 3.5 kcal mol-1.The solvent isotope effect, kH2O/kD2O is 0.68, and discrimination isotope effect (kH/kD) in protonation of the benzylic site of the product is 0.99 +/- 0.05.These ring openings are compared with those of the related cyclopropanols and with the corresponding reaction in a close acyclic analogue.

Diverse photochemistry of sterically congested α-arylacetophenones: ground-state conformational control of reactivity

The effects of α and ortho substituents on the photoreactivity of various α-(o-tolyl)- and α-mesitylacetophenones have been measured. In general, both types of substitution lower the efficiency of cyclization to 2-indanol derivatives in solution. 1,3-Rearrangement of an α-mesityl group to group to form enol ethers and α-cleavage to radicals compete to various degrees, in some cases becoming dominant. Quenching studies in solution show that all three reactions occur from the same n,π* triplet state; α-substitution lowers rate constants for δ-hydrogen abstraction and increases those for α-cleavage and 1,3-rearrangement. X-ray crystal analysis and MMX calculations both show that any additional substitution at the α-carbon of α-aryl (phenyl, tolyl, or mesityl) ketones favors conformers in which the α-aryl group have rotated 120° away from eclipsing the carbonyl. In agreement with this, α-phenyl and α-(o-tolyl) ketones undergo γ-hydrogen abstraction (Norrish type II reaction) with rate constants almost as large as those of the nonarylated ketones. NMR line-broadening studies show that, in most of the α-mesityl ketones, the rate constants for rotation around the mesityl-α-carbon bond (104-106 s-1) are much slower than triplet decay. The same is true for rotations around the carbonyl-α-carbon bond in the α-arylisobutyrophenones. Considered of the spectroscopic evidence, triplet lifetimes, and calculated rotational barriers indicates that ground-state conformational preferences determine which excited-state reactions can occur in most of these ketones. Many of the ketones that cyclize in low yield in solution do so in much higher yield when irradiated as solids, presumably because α-cleavage to radicals becomes mostly revertible. The solid-state reactivity demonstrates that hydrogen abstraction can occur from what are supposedly nonideal geometries; in particular, large values (60-70°) for the dihedral angle and rate constants for hydrogen abstraction in solution plane of the carbonyl π system. The relationship between this angle and rate constants for hydrogen abstraction in solution is discussed. Rate constants for α-cleavage reveal the separate influences of steric congestion and conjugation of the developing benzyl radicals. The 1,3-aryl migration to oxygen appears to arise from initial CT complexation of the α-aryl to the carbonyl; subsequent bonding of oxygen to the benzene ring apparently relieves steric congestion. The 50:50 initial mixture of Z and E enol ethers suggests that the rearrangement is adiabatic, generating enol ether in its twisted triplet state. A large enhancement of indanol yields by alcoholic solvents is suggested to involve protonation of the same CT complex.

Modification of Photochemical Reactivity by Cyclodextrin Complexation: Alteration of Photochemical Behavior via Restriction of Translational and Rotational Motions. Alkyldeoxybenzoins

The photochemical behavior of alkyldeoxybenzoins has been investigated in isotropic organic solvents, in aqueous cyclodextrin solutions, and when they are bound to cyclodextrin in the solid state.Norrish type I and type II reactions occur in these media and the product distributions resulting from these primary processes are dependent on the medium.While in organic solvents the type I and the type II products are obtained in equal amounts, in the aqueous cyclodextrin solution the type II products are formed in large excess.In the solid state the type II products constitute more than 90percent of the product distribution.Ratios of products resulting via elimination and cyclization from the type II 1,4-diradical are also altered by the host cyclodextrin.Conformational and super-cage effects have been invoked to rationalize the dramatic alteration of the photobehavior of alkyldeoxybenzoins by the cyclodextrin.