65095-04-7

Upstream product

• 3412-44-0 (1E)-1,3-diphenylpropene 
• 908094-04-2 phenyldiazomethane 
• 122-78-1 phenylacetaldehyde 
• 100-39-0 benzyl bromide 
• 100-52-7 benzaldehyde 
• 29443-54-7 1,1-diiodo-2-phenylethane 
• 2612-38-6 1,1-dibromo-2-phenylethane 
• 1666-17-7 (E)-N′-benzylidene-4-methylbenzenesulfonohydrazide 

Downstream Products

• 62668-02-4 (E)-1,3-diphenyl-2-propen-1-ol 
• 5381-80-6 1,3-diphenylpropane-1,2-diol 

Relevant academic research and scientific papers

A novel catalytic cycle for the synthesis-of epoxides using sulfur ylides: Application to base sensitive aldehydes

Epoxidation of base sensitive aldehydes can be achieved by a new catalytic cycle which requires the slow addition of a diazocompound to a solution of an aldehyde containing catalytic quantities of a sulfide and catalytic quantities of rhodium acetate.

Simple diastereoselectivity on addition of α-haloalkyl grignard reagents to benzaldehyde

The addition of α-haloalkyl Grignard reagents to benzaldehyde occurs with simple diastereoselectivity substantially higher than that of the corresponding lithium reagents. Reaction in the presence of dimethyl-aluminum chloride suppresses subsequent Oppenauer oxidation of the resulting Mg-alkoxides by excess benzaldehyde.

A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities

A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.

Discrimination of enantiotopic iodine atoms by an iodine/magnesium exchange reaction

An enantioselective iodine/magnesium exchange reaction between the diiodoalkane 4 and a chiral Grignard reagent 12 has been realized at -78°C in THF. The resulting α-iodoalkylmagnesium reagents 13 are configurationally stable under these conditions and during trapping by a benzaldehyde/dimethylaluminium chloride system to furnish the iodohydrins 19 and epoxides 9.

A Novel Catalytic Cycle for the Synthesis of Epoxides Using Sulfur Ylides

A novel, neutral catalytic cycle for the synthesis of epoxides from carbonyl compounds and diazo compounds using catalytic quantities of transition metal salts and sulfides has been developed.In this catalytic cycle, the diazo compounds is decomposed by the transition metal salt to give a metallocarbene, and this is picked up to the sulfide to give a sulfur ylide, which then reacts with the aldehyde to give an epoxide and returns the sulfide back into the catalytic cycle.To obtain good yields of epoxides it is necessary to maintain a low concentration of the diazo compound (by slow addition), otherwise dimerisation of the diazo compound is the dominant reaction.Factors affecting the outcome of the reaction were studied.The reactions are relatively insensitive to solvent, but are sensitive to the structure of the sulfide, the metal salt and the concentration.Unhindered sulfides give good yields of epoxides with any metal salt, but with hindered sufides higher yields are obtained with Cu(acac)2 than with Rh2(OAc)4.The yields of epoxides are sensitive to sulfide concentration especially when using substoichiometric amounts of sulfides.Higher concentration leads to faster rates of formation and subsequent reaction of the sulfur ylides, and consequently to higher yields.This novel catalytic cycle has also been applied to base-sensitive aldehydes.We found that our new catalytic cycle for epoxidation gives much improved yields of epoxides compared to those obtained by traditional sulfur ylide chemistry and is tolerant to a wide variety of sensitive functional groups.Ketones also participate in the catalytic cycle, although they give reduced yields of epoxides compared to aldehydes and require a slightly elevated temperature. - Keywords: catalysis; diazo compounds; epoxidations; sulfur ylides; synthetic methods

A NOVEL CATALYTIC CYCLE FOR THE SYNTHESIS OF EPOXIDES USING SULFUR YLIDES, AND APPLICATION TO THE SYNTHESIS OF CYCLOPROPANES AND AZIRIDINES.

We have developed a new catalytic cycle for the synthesis of epoxides from carbonyl compounds and diazocompounds.These reactions are mediated by catalytic quantities of rhodium acetate (0.01 eq.) and dimethyl sulfide (0.2 eq.).In this catalytic cycle, phenyl diazomethane is decomposed by rhodium acetate to give a metallocarbene and this reacts with the sulfide to give a sulfur ylide which in turn reacts with the aldehyde to give an epoxide and returns the sulfide back into the catalytic cycle.The use of catalytic amounts of chiral sulfides gives non-racemic epoxides.It has been found that other diazocompounds can be used in the catalytic cycle e.g.N,N-diethyl diazoacetamide.In addition, it has been found that substitution of aldehydes for enones furnishes cyclopropanes, and substitution with imines gives aziridines.For the preparation of terminal epoxides, diazomethane could not be used instead of phenyl diazomethane.Instead, it was discovered that terminal epoxides could be prepared using diethyl zinc, chloroiodomethane, dimethyl sulfide and an aldehyde.A second catalytic cycle for epoxidation has therefore been developed.Key Words catalytic, asymmetric synthesis, sulfur ylide, epoxide, aziridine, cyclopropane, rhodium acetate, Simmons Smith.

Solvent Microstructure Effect on Reaction Stereochemistry; Ring Opening of Chalcone Oxides

The stereochemistry and kinetics of acid-catalysed ring-opening reactions of epoxides are reported.Predominant inversion is found in the usual hydroxylic solvents.As the nucleophilicity of the solvent diminishes and acidity increases, the stereochemistry changes to predominant retention.Electron-donating substituents also tend to favour retention.In mixed solvents, the solvent microstructure is altered, leading to net retention for nucleophiles such as methanol.The exception is dioxane-methanol, which gives enhanced inversion.Molecular mechanics calculations indicate an electrostatic preference for the retention route, but a steric preference for inversion.The activation parameters indicate a negative entropy for both inversion and retention paths.Possible reasons are discussed for the entropy of the retention route being in the range normally found for A2 reactions.

Stereospecific Desulfinylation of α,β-Epoxy Sulfoxides with Butyllithium. A New Synthesis of Epoxides and Allylic Alcohols from Carbonyl Compounds

Desulfinylation of α,β-epoxysulfoxides, easily prepared from carbonyl compounds and 1-chloroalkyl phenyl sulfoxide, with 1 equivalent of butyllithium at low temperature gave epoxides in good yields.The similar α,β-epoxy sulfoxides having an arylmethyl gro