Trans-2-phenyl-3-

Thietanes can also be prepared by ring contraction of higher-membered heterocyclic rings. Thermolysis of the dithiolane dioxide 129 in benzene leads to trans-2-phenyl-3-benzoylthietane (130) and benzalacetophenone (Eq. 20). 

Photolysis of trans-2-phenyl-3-benzoylthietane yields both cis- and trans-l,3-diphenyl-2-ethenyl ketone and polymeric thioformaldehyde instead of the anticipated thiophene derivative. 

The rates of radical-forming thermal decomposition of four families of free radical initiators can be predicted from a sum of transition state and reactant state effects. The four families of initiators are trarw-symmetric bisalkyl diazenes,trans-phenyl, alkyl diazenes, peresters and hydrocarbons (carbon-carbon bond homolysis). Transition state effects are calculated by the HMD pi- delocalization energies of the alkyl radicals formed in the reactions. Reactant state effects are estimated from standard steric parameters. For each family of initiators, linear energy relationships have been created for calculating the rates at which members of the family decompose at given temperatures. These numerical relationships should be useful for predicting rates of decomposition for potential new initiators for the free radical polymerization of vinyl monomers under extraordinary conditions. 

Predictive equations for the rates of decomposition of four families of free radical initiators are established in this research. The four initiator families, each treated separately, are irons-symmetric bisalkyl diazenes (reaction 1), trans-phenyl, alkyl diazenes (reaction 2), tert-butyl peresters (reaction 3) and hydrocarbons (reaction 4). The probable rate determining steps of these reactions are given below. For the decomposition of peresters, R is chosen so that the concerted mechanism of decomposition operates for all the members of the family (see below)... 

Since the quantum chemical calculations used to parameterize equations 6 and 7 are relatively crude semiempirical methods, these equations should not be used to prove or disprove differences in mechanisms of decomposition within a family of initiators. The assumption made in the present study has been that the mechanism of decomposition of initiators does not change within a particular family of initiators (reactions 1-4). It is generally accepted that trow5-symmetric bisalkyl diazenes (1) decompose entirely by a concerted, synchronous mechanism and that trans-phenyl, alkyl diazenes (2) decompose by a stepwise mechanism, with an intermediate phenyldiazenyl radical (37). For R groups with equal or larger pi-... 

C14H12O2S, trans-Phenyl styryl sulfone [( )-(2-Phenylethenyl)sulfonylbenzene]... 

The reaction of xenon difluoride with a series of cis- and trans-phenyl substituted alkenes was examined in detail. 1,1-Diphenylethene, l,1-diphenyl-2-fluoroethene and 1.1-diphenyl-propene form vicinal 1,2-difluoro derivatives in 65 95% yield in dichloromethane solution with hydrogen fluoride as the catalyst.29-32 Two possible mechanisms were discussed.33... 

A requirement for the enone rearrangement is the presence of a rc-moiety at carbon-4 (i.e. at the 7-carbon). The rearrangement proceeds with migration of this group to C-3 (the -carbon). The preferred stereochemical course leads preferentially to the 6-endo phenyl configuration (i.e. trans phenyl groups here). The overall reaction is shown in equation 3... 

Analogous products were reported for t-1 and 2-methyl-4,5-di-hydrofuran. Subsequent investigation of the former reaction by Kaupp and co-workers (104) established that 42 and 44 rather than 43 are the two stereoisomeric products. Cycloadducts with trans phenyl groups analogous to 42 and 44 were obtained with several other cyclic ethers (104). 

All the other cycloadditions, such as the [4+2] cycloadditions of allyl cations and anions, and the [8+2] and [6+4] cycloadditions of longer conjugated systems, have also been found to be suprafacial on both components, wherever it has been possible to test them. Thus the trans phenyl groups on the cyclopentene 2.65 show that the two new bonds were formed suprafacially on the rrans-stilbene. The tricyclic adducts 2.61, 2.77, 2.79, and 2.83, and the tetracyclic adduct 2.82, show that both components in each case have reacted suprafacially, although only suprafacial reactions are possible in cases like these, since the products from antarafacial attack on either component would have been prohibitively strained. Nevertheless, the fact that they have undergone cycloaddition is important, for it is the failure of thermal [2+2], [4+4] and [6+6], and photochemical [4+2], [8+2] and [6+4] pericyclic cycloadditions to take place, even when all-suprafacial options are open to them, that is significant. 

Some of the major drugs in the category of MAOs include phenelzine, 50, moclobemide, 51, toloxatone, 52, and others. Tranylcypromine (trans-phenyl-cyclopropylamine), 53, was one of the first MAO inactivators approved for clinical use [6]. 

C12H15N04 cotarnine 82-54-2 25.00 1.1892 2 24305 C12H17NO 2-cis-hydroxymethyl-4-trans-phenyl-1 -cyclohe. .. 23 3 1 04 ... 

The third synthesis, by Crombie et al., utilizes the base-catalysed condensation of the trans,trans-phenyl farnesyl sulphone (10) with trans,trans-Qthy farneso-ate to give the ester (11) as a major product via the intermediate (12). Lithium aluminium hydride reduction again yielded presqualene alcohol (1). In each case the labelled synthetic alcohol, as its pyrophosphate, was incorporated by yeast subcellular particles into squalene in ca. 68 % yield. The minor synthetic isomers were not incorporated. 

N-Phenyl-/y-naphthylamine, 336, 846 trans Phenyl-o-nitrocinnamic acid, 1200 Phenylnitromethane, 691, 822 vPh iylnonanoic acid, 707-708 Phenylnorcarane, endo- and exo-, 1250-1251 Phenylosazones, 694,1099 5-Phenyl-1,4-pentadienaI, 669 8-Phenyl-2,4-pentadienic anhydride, 794... 

Fig. 10. Lipase. Stereospecific transesterification of methyl trans- -phenyl glycidate, precursor of the side chain of Taxol [135]...

Table 8.3 summarizes the energetic residts for the five cases as obtained from MM3 molecular mechanics treatment of the first intermediate in the mini-crystal lattice. Again, we note that the species formed by migration of the trans-phenyl... 

Enone Cis-Phenyl Migration Trans-Phenyl Migration... 

Reversible C-S bond cleavage of diaryl sulfide is known. Treatment of Ni(cod)2 with phenyl p-tolyl sulfide in the presence of PEt3 results in the C-S bond cleavage at room temperature, giving a mixture of h a 5-(benzenethiolato)(/5-tolyl)nickel(II) and trans-(phenyl)(/ -toluenethiolato)nickel(II) (Eq. 3.37) [146]. Heating of the reaction mixture leads to the equilibration suggesting reversible oxidative addition/reductive elimination (Scheme 3.77). 

Both unimolecular cyclizations and condensation reactions have been used to effect closure of the 1,4-dioxocin ring. Although these are discussed separately below, the condensation reactions presumably occur in a stepwise manner, and thus formally are perhaps better considered to be cyclization reactions also. Photoinduced remote cyclization of ketoethers (157 R = H, Me) affords the corresponding dioxocanones (151) in 48% (R = H) and 76% (R = Me) yield, apparently via an intermediate i/-atom abstraction via a ten-membered ring-transition state (Scheme 42). Compound (151 R = H) is obtained as a single stereoisomer, presumably with trans phenyl groups, while (151 R = Me) is obtained as a ca. 1 1 mixture of cis and trans isomers <91CC1617>. 

Comparison of antibacterial activity of the four 2 -methyl enantiomers has shown that cis analogs are much more potent than the trans. There is relatively little difference between enantiomers but the VR, IS isomer is significantly more active. In the case of both 2 -trans-phenyl enantiomers, the most active one (rs, 2 R) is only 4 times as active as its enantiomer. 

Yamaguchi T, Harada N, Ozaki K, Hayashi M, Arakawa H, Hashiyama T (1999) Synthesis of Taxoids 4. Novel and Versatile Methods for Preparation of New Taxoids by Employing cis- or trans-Phenyl Glycidic Acid. Tetrahedron 55 1005... 

C1bHi9NO2, 1-Methyl-4-trans-phenyl-4-benzyl-5-hydroxy-pyrrolidine-2-one, 44B, 199... 

On the other hand, bulky ligands in c/s-position exhibit large steric effects. Thus, in the reaction (2.8.8), the replacement of trans-phenyl by trans-mesityl (mesitylene = 1,3,5-trimethylbenzene) leads to a rate decrease by a factor of 30, but if phenyl is in ds-position the rate decrease factor is about 10 ... 

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