Indene number

Work on the thiazolopyridines has been centered on the 2-methyl derivatives and their conversion into cyanine dyes. Takahashi et al. prepared a number of substituted thiazolo[5,4-6]pyridines (109 Y =.MeO,i6 EtO, Cl,i6 and EtgNi ), all of which form methiodides (110) as evidenced by the high reactivity of the 2-methyl group. A parallel will be seen between these compounds and the l,4-diaza-3fi -indenes. Kiprianov reports the interesting observation that the etho-toluene- -sulfonate of 109 (Y = H) does not contain a reactive methyl group presumably when Y is H the steric and electronic... 

Because of the yield of only 16% in the synthesis of 239, the overall yields of cycloadducts with reference to indene according to Scheme 6.54 are rather low, however. A substantial improvement was achieved by the development of a one-pot procedure, which starts from indene and takes advantage of its dibromocarbene adduct (254) (Scheme 6.55). This was prepared at -60 °C with tetrabromomethane and MeLi as source for the carbene and remained unchanged in solution up to temperatures around 0 °C [92]. If an activated alkene and MeLi were added sequentially to such a solution at -30 C, cydoadducts of 221 were isolated in a number of cases in relatively good yields. In Scheme 6.55, this procedure is illustrated by the example of 1,3-cyclopentadiene, which furnished the [4 + 2]-cydoadducts 255 and 256, both as a mixture with endo exo= 2 1, in the ratio of 8 1 in 23% yield with reference to indene [67]. Analogously, the products from 221 and styrene, 1,3-butadiene [92] and 2,3-dimethylbutadiene [66], namely the compounds 240, 241, 246-249 and 250-253, were obtained in yields of 40, 24 and 25%, respectively, by means of the one-pot procedure from indene. 

Styrene and indene derivatives (Scheme 2, Y = Ph) are dimerized to l,4-dimethoxy-l,4-diphenylbutanes or 1,4-diphenylbutadienes (Table 7, numbers 1 and 2) [52]. The product distribution is in some cases strongly dependent on the anode potential and the supporting electrolyte. Dimerization is promoted by a-substituents that stabilize the intermediate radical cation, for example, phenyl, vinyl, alkoxy, dialkylamino groups. IJ-Alkyl substituents strongly decrease the yield of dimers and favor formation of dimethoxy-lated monomers. 

Cyclic olefins and diolefins form much more aerosol than 1-alkenes that have the same number of carbon atoms (for example, cyclohexene 1-hexene, and 1,7-octadiene 1-octene). The same effect of chain length and double-bond position is observed for diolefins (1,7-octadiene > 1,6-heptadiene > 1,5-hexadiene, and 1,7-octadiene 2,6-octadiene). Heavier unsaturated cyclic compounds, such as indene and terpenes, form even more aerosol. 

In between these extremes lie a large number of CVM treatments which use combinations of different cluster sizes. The early treatment of Bethe (1935) used a pair approximation (i.e., a two-atom cluster), but this cluster size is insufficient to deal with fhistration effects or when next-nearest neighbours play a significant role (Inden and Pitsch 1991). A four-atom (tetrahedral) cluster is theoretically the minimum requirement for an f.c.c. lattice, but clusters of 13-14 atoms have been used by de Fontaine (1979, 1994) (Fig. 7.2b). However, since a comprehensive treatment for an [n]-member cluster should include the effect of all the component smaller (n — 1, n — 2...) units, there is a marked increase in computing time with cluster size. Several approximations have been made in order to circumvent this problem. 

The cluster site approximation, CSA, has the great advantage that the required number of equations to handle the necessary variables is given by the product Cn (Oates and Wentl 1996) as compared to the exponential value C" aassociated with a full CVM treatment (Inden and Pitsch 1991). The CSA is a variant of the quasichemical model proposed by Li as early as 1949, where the number of clusters that are considered to contribute to the entropy are reduced by excluding all clusters that share edges or bonds. Kikuchi (1977) has deduced the consequential changes in entropy for an f.c.c. structure (Eqs 7.32 and 7.33), which places CSA intermediate... 

Equation (8.14) leads to a value for 4> = 0.25 at which is of comparable magnitude to the values assumed by Inden (1981a), although it clearly does not include any dependence on the co-ordination number z. 

Other bicyclic ozonide examples are given in Scheme 37. The number of examples available reflects the inherent stability of this type of trioxolane ring system. The x-ray structures of several of these 1,2,4-trioxolanes have been discussed in Section 4.16.3.1. Substituted indene derivatives... 

Monitoring data on 2,3-benzofuran in environmental media are scarce. Potential human exposure to 2,3-benzofuran may occur by ingestion of foods treated with coumarone-indene resin however, migration of 2,3-benzofuran from this resin has not been confirmed. Occupational exposure to 2,3-benzofuran may occur in several energy-related industries, and individuals living in the vicinity of hazardous waste sites at which this compound has been detected may also be exposed. The EPA has identified 1,177 NPL sites. 2,3-Benzofuran has been found at 5 of the sites evaluated for the presence of this chemical (View 1989). However, it is not known how many of the 1,177 NPL sites have been evaluated for 2,3-benzofuran. As more sites are evaluated by the EPA, the number may change. The frequency of the sites in the United States at which... 

No regulations or advisories that apply specifically to 2,3-benzofuran were located. 2,3-Benzofuran is one component of coumarone-indene resin and a number of regulations and guidelines have been established for coumarone-indene resin by various national agencies. These values are summarized in Table 7-1. 

Reaction of atomic carbon with alkenes generally involves both DBA and vinyl C—H insertion. An interesting example is the reaction of C atoms with styrene in which the major products are phenylallene (21) and indene (22). The synthesis of a number of specifically deuterated styrenes and the measurement of the deuterium isotope effects on the 21/22 ratio led to the conclusion that 21 was formed by DBA followed by ring expansion and by C—H(D) insertion into and followed by rearrangement of the resultant frawi-vinylcarbene (23). The indene was formed by C—H(D) insertion into Xb followed by cyclization of the resultant cw-vinylcarbene (24) (Eq. 18). An examination of the product ratios and their label distributions when atoms are used leads to the conclusion that the ratio of C=C addition to C—H insertion is 0.72 1 in this case. 

A number of gem-dibromocyclopropane derivatives has been reacted with aromatic compounds in the presence of aluminum chloride or ferric chloride providing indenes in yields up to 80%. To rationalize this interesting anellation process it has been proposed that the cyclopropyl cation formed under the influence of the Lewis acid collapses to an allylic ion, which then functions as the alkylating agent [179],... 

Analytical pyrolysis with field ionization mass spectrometry (online Py-FIMS) or in combination with GC/MS (Curie point Py-GC/MS) led to a significant increased number of identified subunits (e.g., Bracewell et al., 1989 Schulten et al., 2002). In addition, the application of tetramethylammonium hydroxide (TMAH) methylation, followed by GC/MS, was successfully applied. The most abundant pyrolysis products identified are benzene, phenol and furan derivatives, aliphatic and carboxylic compounds, and indene derivatives (Schulten et al.,2002). New approaches have been used for the quantification of n-alkyl fatty acids of DOM and isolated fractions in the form of individual compounds after solvent extraction followed by derivatiza-tion with TMAH. 

Figure 2-13 Raman spectrum of indene. The wavenumbers of the numbered bands are listed in Table 2-7.

Collins et al. have studied a number of reactions in excess tetralin at 400°C (15). They reported 99% conversion of indene to indane after 1 hour and conversion of cyclohexene and 1-cyclohexenylbenzene to cyclohexane and cyclohexylbenzene after 18 hours. At 400°C values in Table V predict nearly complete (>90%) hydrogenation of both indene and 1-cyclohexenylbenzene after 1 hour and a conversion of cyclohexene to cyclohexane at a rate of 40% per hour. Molecular disproportionation is a feasible pathway for these reactions. 

The trithionium salts also condense with the weak C—H acids cyclopentadiene, indene, and fluorene, but again only when the latter are present as their sodium salts. As we have already pointed out, however, the reactions with such strong bases are rather unpredictable, and the desired 1,2-dithiafulvalenes (146) may be obtained (if at all) only in very low yields, together with a large number of by-products. The formation of some of these by-products is attributed to the fact that the 1,2-dithiafulvalenes, like the sesqui-fulvalenes, also react as fulvenes and add on strong bases.112... 

The asymmetric oxidation of indene to the corresponding epoxide (Equation 24) is carried out commercially by Sepracor on a small scale. Chiral indene oxide is an intermediate in the synthesis of crixivan (an HIV protease inhibitor). Reaction is carried out at 5°C with moderately high turnover numbers in the presence of an exotic donor ligand ( P3NO , 3-phenylpropylpyridine N oxide) and sodium hypochlorite as the terminal oxidant. A similar epoxidation of a simple cis olefin (Equation 25) leads to an enantiomerically pure amino-alcohol used in the synthesis of taxol, a potent anticancer drug. 

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