By Thermal Rearrangement

Trichlorosilane. The primary production process for trichlorosilane is the direct reaction of hydrogen chloride gas and sihcon metal in a fluid-bed reactor. Although this process produces both trichlorosilane and sihcon tetrachloride, production of the latter can be minimi2ed by proper control of the reaction temperature (22). A significant amount of trichlorosilane is also produced by thermal rearrangement of sihcon tetrachloride in the presence of hydrogen gas and sihcon. 

Trimethyl isocyanurate [827-16-7] can be synthesized in 60% yield by the reaction of CA with dimethyl sulfate in alkaline medium (13) or with diazomethane (63) and in essentially quantitative yield by thermal rearrangement of trimethyl cyanurate [877-89-4]. Isomerization of alkyl cyanurates to the corresponding isocyanurates is frequendy observed (11,64). 

When 6-APA is diazotized in the absence of an anion more nucleophilic than water, or when a 6-diazopenicillanate is treated with aqueous nonnucleophilic acid, 6o -hydroxy-penicillanates are produced (67HCA1327, 74JOC1444). Esters of these compounds can be formed either by acylation, or by thermal rearrangement of the corresponding N-... 

Other convenient routes to carboranes, selected from the growing number of recently reported syntheses, are as follows. Monocarbon carboranes can be prepared in good yield by the transition-metal catalysed hydroboration of alkenes followed by thermal rearrangement of the intermediate product, c.gP" ... 

Scientists at DuPont Merck Pharmaceuticals [31] had also developed a new process to prepare 37, based on a modification of the Corey-Fuchs method, from cyclopropylaldehyde, prepared by thermal rearrangement of butadiene monoxide. 

Michael addition of amidoxime 7 to DMAD, followed by thermal rearrangement. 

Other organosilicon polymer precursors for ceramics have either been prepared or improved by means of transition metal complex-catalyzed chemistry. For instance, the Nicalon silicon carbide-based ceramic fibers are fabricated from a polycarbosilane that is produced by thermal rearrangement of poly(dimethylsilylene) [18]. The CH3(H)SiCH2 group is the major constituent of this polycarbosilane. 

The process has been applied to the synthesis of a A9-19-nor-10-azatesto-sterone 378 by cycloaddition of nitrile oxide 377 to MCP followed by thermal rearrangement of the adduct (Scheme 52) [94]. 

The single crystal X-ray structure of the enantiopure tetrahydro oxepin-2-one 61, a mimic of steroidal androgens, has been reported <06ZN(B)111>. A new procedure has been described for the synthesis of substituted furano-fused oxepines based on expoxidation of strained fused cyclobutenes followed by thermal rearrangement <06OL5183>. 

The cyclononadiene in (4.72) is obtained by thermal rearrangement of the photoadduct of a cyclobutene carboxylic acid ester and cyclopentene 484). 

The anodic oxidation of 7-MeO-CHT in MeOH results in the formation of benzalde-hyde dimethyl acetal through a ring contracting rearrangement, whereas 3-MeO-CHT and 1-MeO-CHT are prepared by thermal rearrangement of 7-MeO-CHT and afford 7,7-diMeO-CHT in 83% and 85% yields, respectively, upon the anodic oxidation. The hydrolysis of 7,7-diMeO-CHT in 5% aqueous H2SO4 gives tropone in 85% yield (equation 17). 

Additional C-S substituted derivatives are formed by thermal rearrangements of phenylthiocyanate-trichloroborane and chloromethylthiocyanate-trichloroborane adducts respectively ... 

The related derivative (79), obtained by thermal rearrangement of the /V-oxide of (78), also exhibits excellent prodrug properties [110], This compound, when administered orally to mice, liberates excellent levels of norfloxacin and is slightly more effective in mouse protection tests than (78) and significantly better than norfloxacin. 

In both cyclic and acyclic dienes which can achieve the necessary geometry the [1, 5] shift is commonly observed because the activation energy is lowest for the transition states involving minimal distortion. This is particularly so in cyclopentadienes and indenes. The preference for [1, 5] over [1, 3] shifts is demonstrated by thermal rearrangement of 1-duterioindene. At 200°C, deuterium became scrambled over all three non-benzenoid carbons. 

Symmetrical 5,5-dialkyl dithiocarbonates have been obtained by thermal rearrangement of the corresponding (9,5-dialkyl esters in the presence of Aliquat [43]. This procedure is not suitable for the preparation of unsymmetrical 5,5-dialkyl dithiocarbonates, as it has been reported that disproportionation of the products can lead to a mixture of the symmetrical and unsymmetrical esters. Alternatively, they can be prepared by a base-catalysed disproportionation of 5-alkyl-O-methyl dithiocarbonates [44] (Table 4.9). These methods for the synthesis of the 5,5-dialkyl esters are more convenient than the traditional procedures from the thiol and phosgene. 

Spruce meal and beech blocks were modified by using a mixture of perfluoroalkyl ethanol and MDI. Improved dimensional stability and water repellency were reported (Engonga etal., 1999). In order to avoid the handling problems associated with the use of most isocyanates, the generation of isocyanates within the wood by thermal rearrangement of acyl azides has been studied (Gdrardin etal., 1995) (Figure 4.8). This is potentially a... 

Hydroxythiadiazoles can be converted into chloro compounds by the usual methods, for example with POCI3. The 0-acylation of the sodium salt of hydroxythiadiazoles with dimethylthiocarbamoyl chloride followed by thermal rearrangement of the thiolcarbamate and hydrolysis is a convenient route to l,2,5-thiadiazole-3-thiones <73CJC2349>. 

Elemenone (359), a compound which co-occurs with germacrone (358) in Bulgarian zdravetz oil and which can be formed from germacrone (358) by thermal rearrangement, has recently been synthesized by a route (Scheme 34) in which the... 

Examples of the synthesis of fused-ring azetidines by ring closure onto a preformed azetidine are uncommon, in contrast to approaches used for the preparation of fused ring azetidinones (see Sections 5.12.3, 5.11.4.4 and 5.10.4.3). The l,3-diazabicyclo[3.2.0]hep-tane derivative (48) was prepared (72JOC516) by cyclization with DCC of the carbamoyl-azetidine followed by thermal rearrangement of the intermediate thiazolidinone (Scheme 6). 

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