Phenylethanal reaction

Only a few secondary /3-deuterium KIEs have been measured for homolytic reactions and the mechanistic utility of these, invariably small, KIEs is limited. The first secondary /3-deuterium KIE for a radical reaction was published by Seltzer and Hamilton in 1966. They found a small (kH/k0)p = 1.052 (= 1.017 per D) for the thermal decomposition of the azo-bis(l-phenylethane) (reaction (40)) at 105°C in ethylbenzene and concluded that it was due to hyperconjugation... 

Pis commonly have been synthesized from reactions of pyromellitic dianhydride [26265-89-4] (PMD A) or 3,3H,4 -benzophenone tetracarboxyUc dianhydride [2421-28-5] (B IDA) with a number of diamines like 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-amino-3-methylphenyl)propane, I,I-bis(4-aminophenyl)-I-phenylethane, and 1,1-his(4-amino-3-methy1pheny1)-1-phenylethane (5). The PMDA-based Pis were thermally more stable than the corresponding Pis obtained from BTDA. 

What product would you expect from a nucleophilic substitution reaction of (R)-l-bromo-l-phenylethane with cyanide ion, C=N, as nucleophile Show the stereochemistry of both reactant and product, assuming that inversion of configuration occurs. 

As far as the reactions with benzyl chlorides are concerned (74), the oxidative addition of benzyl chloride and substituted benzyl chlorides to palladium atoms yields rj -benzylpalladium chloride dimers. The parent compound, bis(l,2,3-7 -benzyl)di-/i,-chloro-palladium(II), quantitatively adds four molecules of PEts by first forcing the rj -benzyl-iy -benzyl transformation, with subsequent breakage of the Pd-Cl bridges to form trans-bistPEtsKbenzyDchloroPddI). The spectral characteristics of the parent molecule are indicative of the allylic type of bonding. Similar i7 -benzyl compounds were formed from 4-methylbenzyl chloride, 2-chloro-l,l,l-trifluoro-2-phenylethane, and 3,4-dimethylbenzyl chloride. 

The solvent-free 0-silylation reaction can also be accomplished selectively. For example, when l-methyl-l-phenylethane-l,2-diol (39) was treated with 27 at 60 °C for 5 h, its primary hydroxyl group was silylated to give 40 in 70% yield. 

The asymmetric hydrosilylation that has been most extensively studied so far is the palladium-catalyzed hydrosilylation of styrene derivatives with trichlorosilane. This is mainly due to the easy manipulation of this reaction, which usually proceeds with perfect regioselectivity in giving benzylic silanes, 1-aryl-1-silylethanes. This regioselectivity is ascribed to the formation of stable 7t-benzylpalladium intermediates (Scheme 3).1,S Sa It is known that bisphosphine-palladium complexes are catalytically much less active than monophosphine-palladium complexes, and, hence, asymmetric synthesis has been attempted by use of chiral monodentate phosphine ligands. In the first report published in 1972, menthyldiphenylphosphine 4a and neomenthyldiphenylphosphine 4b have been used for the palladium-catalyzed reaction of styrene 1 with trichlorosilane. The reactions gave l-(trichlorosilyl)-l-phenylethane 2 with 34% and 22% ee, respectively (entries 1 and 2 in Table l).22 23... 

Recently, Schaumann et al. 153,154 an(j Bienz et tf/.155,156 have developed dependable routes for the resolution of racemic functionalized organosilanes with Si-centered chirality using chiral auxiliaries, such as binaphthol (BINOL), 2-aminobutanol, and phenylethane-l,2-diol (Scheme 2). For instance, the successive reaction of BINOL with butyllithium and the chiral triorganochlorosilanes RPhMeSiCl (R = /-Pr, -Bu, /-Bu) affords the BINOL monosilyl ethers 9-11, which can be resolved into the pure enantiomers (A)-9-ll and (7 )-9-11, respectively. Reduction with LiAlFF produces the enantiomerically pure triorgano-H-silanes (A)- and (R)-RPhMeSiH (12, R = /-Pr 13, -Bu 14, /-Bu), respectively (Scheme 2). Tamao et al. have used chiral amines to prepare optically active organosilanes.157... 

Not unexpectedly, alkylation of the double carbonylated complex proceeds via a base-catalysed interfacial enolization step, but it is significant that the initial double carbonylation step also involves an interfacial reaction, as it has been shown that no pyruvic acid derivatives are obtained at low stirring rates. Further evidence comes from observations of the cobalt-catalysed carbonylation of secondary benzyl halides [8], where the overall reaction is more complex than that indicated by Scheme 8.3. In addition to the expected formation of the phenylacetic and phenylpyruvic acids, the reaction with 1-bromo-l-phenylethane also produces 3-phenylpropionic acid, 2,3-diphenylbutane, ethylbenzene and styrene (Scheme 8.4). The absence of secondary carbonylation of the phenylpropionylcobalt tetracarbonyl complex is consistent with the less favourable enolization of the phenylpropionyl group, compared with the phenylacetyl group. 

The dehydrohalogenation of 1- or 2-haloalkanes, in particular of l-bromo-2-phenylethane, has been studied in considerable detail [1-9]. Less active haloalkanes react only in the presence of specific quaternary ammonium salts and frequently require stoichiometric amounts of the catalyst, particularly when Triton B is used [ 1, 2]. Elimination follows zero order kinetics [7] and can take place in the absence of base, for example, styrene, equivalent in concentration to that of the added catalyst, is obtained when 1-bromo-2-phenylethane is heated at 100°C with tetra-n-butyl-ammonium bromide [8], The reaction is reversible and 1-bromo-l-phenylethane is detected at 145°C [8]. From this evidence it is postulated that the elimination follows a reverse transfer mechanism (see Chapter 1) [5]. The liquidrliquid two-phase p-elimination from 1-bromo-2-phenylethanes is low yielding and extremely slow, compared with the PEG-catalysed reaction [4]. In contrast, solid potassium hydroxide and tetra-n-butylammonium bromide in f-butanol effects a 73% conversion in 24 hours or, in the absence of a solvent, over 4 hours [3] extended reaction times lead to polymerization of the resulting styrene. 

Table 9.1). The rate of dehydrobromination from the intermediate bromoalkenes follows the pattern 2-bromoalkenes > Z-l-bromoalkenes > E- -bromoalkenes the corresponding chloro derivatives react more slowly. For optimum yield, the reaction temperature should be <100°C to reduce decomposition of the catalyst, and the concentration of base should be kept low to prevent isomerization of the resulting alkynes. [3-Elimination of HBr from 1,2-dibromo-1 -phenylethane can be controlled to yield 1-bromo-l-phenylethene in 83% yield [15]. The addition of alcohols and diols have a co-catalytic effect on the elimination reaction, as the alkoxide anions are transferred more effectively than the hydroxide ions into the organic phase [13]. 

Asymmetric ferrocenyl ligands bearing different donor atoms connected through a chiral carbon atom have been used by many groups for different enantioselective reactions. Diferrocenyl dichalcogenides 107-109 were synthesized by Uemura et al. and tested in the ATH of acetophenone in the presence of [lr(cod)Cl]2 in PrOH/NaOH to give (Rj-phenylethan-l-ol at moderate conversions and enanh-oselechvities (Scheme 4.49) [95]. 

Early claims to have prepared 4-hydroxy-4H-imidazoles from benzami-dine hydrochloride (27) and 2,3-butanedione (28), or phenylethane-1,2-dione (29), appear to be substantially correct (Scheme 9). Although this work has not been repeated, analogous intermediates have been observed subsequently in related reactions. Waugh and co-workers recognized that 30 might well have been the rearranged isomer 31. (see Section IV,A,l,b). 

Higher diastereoselectivities in ring opening of bicyclic anhydrides are obtained through their diphenylboryl trifluoromethanesulfonate catalyzed reaction with (7 )-l-diphenylboryloxy-2-methoxy-l-phenylethane in toluene at 0CC98. 

When enantiomerically pure (/ )- and (S)-ll were reacted with racemic 1-bromo-l-phenylethane (13), d.r. s of 97 3 were obtained. The somewhat lower d.r. obtained on reaction of the resolved complexes was explained as a mass action effect during the course of the reaction the reactive enantiomer of the haloalkane is depleted relative to the less reactive enantiomer. 

Phenylacetaldehyde can be obtained in high yield by vapor-phase isomerization of styrene oxide, for example, with alkali-treated silica-alumina [147]. Another process starts from phenylethane-l,2-diol, which can be converted into phenylacetaldehyde in high yield. The reaction is performed in the vapor phase in the presence of an acidic silica alumina catalyst [148]. 

To a flask containing 6.9 gm (0.05 mole) of phenylethane-l,2-diol in 25 ml of chloroform is added dropwise at room temperature 5.95 gm (0.05 mole) of thionyl chloride. After the initial reaction in which hydrogen chloride is evolved, the solution is refluxed for 1 hr. The solution is cooled, washed with water, then with 2 % sodium bicarbonate solution, dried, and distilled to afford 5.7 gm (62%) b.p. 62°-64°C (0.15 mm), n 4-6 1.5421. 

Reaction of AT-fluorobis(trifluoromethylsulfonyl)amine (Id) with alkenes gives various products, depending on the reaction conditions and the structure of the substrate. In solvents of higher nucleophilicity such as water, acetic acid, aqueous hydrochloric acid, and 70 % hydrogen fluoride/pyridine, a-fluorohydrins or their acetates, a-chloro-fl-fluoroalkanes or a,/ -difluoroal-kanes, e.g. 14. are obtained.146 Reaction of styrene and ( >l-phenylpropene with Id in dich-loromethane/acetic acid gives l-acetoxy-2-fluoro-l-phenylethane and -propane, in 92 and 99 % yield, respectively, the latter product in a ratio (erythrojthreo) 1 l.146... 

Thioketals are readily prepared by treating the corresponding ketone with ethanedithiol and propane-1,3-dithiol. The 12-ketone fails to react with monothiols such as ethanethiol or thiophenol92 or with the bulkier 1-phenylethane-1,2-dithiol or tetralin-2,3-dithiol.93 The A9(11)-12-ketone readily forms a thioketal on reaction with ethanedithiol.28 The selective protection of 11,12-diones (83) as the 12-monothioketals (84) is possible due to the poor reactivity of the 11-ketone.46,10... 

Exercise 22-41 Write reasonable mechanisms for the different oxidation reactions of cyclooctatetraene with mercuric ethanoate in ethanoic acid, methanol, and water solutions. Notice that compounds of the type Hg(OR)2 appear to act in some cases as OR-donating agents and also that the oxide produced from cyclooctatetraene and peroxyacids (Section 15-11C) rearranges readily in the presence of acids to phenylethanal. 

Irradiation of t-1 with saturated tertiary aliphatic amines in nonpolar solvents results only in isomerization of t-1 (113, 118,131). In contrast, irradiation in polar aprotic solvents results in the formation of a t-l-amine adduct (63), 1,2-di-phenylethane (64), and 1,2,3,4-tetraphenylbutene (65), as shown in eq. 22 for the reaction with triethylamine. 

A third pathway for oxime formation is given by tautomerization of nitroso compounds possessing an a-hydrogen (equation 9). Such a process involves an intramolecular redox reaction, in which the nitrogen undergoes a formal two-electron reduction, while the a-carbon is oxidized. Kinetic analysis of this conversion, as performed with a set of a-substituted 2-nitroso-l-phenylethane compounds, has revealed sensitivity toward both the bulkiness of the substituents and the initial concentration of the nitroso dimers128. For instance, tautomerization of 2-nitroso-l-phenylpropane to 28 has been proposed to play a role in the metabolism of methamphetamine by fortified rat liver tissue129. 

C. l-Broino-2-phenylethane reactant undergoes a one step substitution reaction. 

Application of Accelerating Rate Calorimetry (ARC) in Evaluating a Reaction with a Potentially Explosive Nitro Compound. One of our process development projects required the preparation of 2-hydroxy-l-nitro-2-phenylethane via the addition of sodium methoxide to a mixture of one mole of benzaldehyde and one mole of nitromethane in methanol (Scheme 1). 

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