Examples General Synthesis

Because authors have approached similar topics from different viewpoints, index entries to those topics may appear under several headings. Thus a reader interested in, for example, the synthesis of acetyl-3Tf-azepin-2-ones should refer both to general entries (e.g. Azepinones, Azepin-2-ones, 3JT-Azepin-2-ones) and to specific entries (e.g. 3JT-Azepin-2-one, 3-acetyl- 3f7-Azepin-2-one, 7-acetyl-). 

In their general synthesis of quinoline-2,5,8(lf/)-triones, Avendano and coworkers use this modified protocol to access the key 2,5-dimethoxyanilide systems 11 required in their synthetic plan." For more examples, see reference 11 and references cited within. 

All the halide exchange reactions mentioned above proceed more or less quantitatively, causing greater or lesser quantities of halide impurities in the final product. The choice of the best procedure to obtain complete exchange depends mainly on the nature of the ionic liquid that is being produced. Unfortunately, there is no general method to obtain a halide-free ionic liquid that can be used for all types of ionic liquid. This is explained in a little more detail for two defined examples the synthesis of [BMIM][(CF3S02)2N] and the synthesis of [EMIM][BF4]. 

In general, isotopic exchange is both expensive and difficult. In the case of many room-temperature ionic liquids, however, the manufacture of deuterated ionic liquids is relatively easily achievable. For example, the general synthesis of l-allcyl-3-methylimidazolium salts is shown in Scheme 4.1-1 [2]. This methodology allows maximum flexibility in the deuteration on the imidazolium cation that is, it can be either ring or side chain deuteration or both. 

Polyphosphonates are well-known flame-retardant materials [110] and are generally prepared by melt [111,112], interfacial [113-115] and solution polycondensation methods [116]. A typical example of synthesis is the polycondensation of bifunctional organophosphorus compounds, such as dichlorophenylphosphine oxide, with bisphenols [117,118]. 

Although the introduction of a substituent at both C-a and C-P may be expected to destabilize the transoid state of rearrangement due to additional 1,2-allylic interactions, the tendency to form an -double bond exclusively is retained in the synthesis of trisubstituted olefins as well. The first such report, shortly following the initial Evans report , was made by Grieco who achieved a completely stereospecific general synthesis of ( )-y-substituted methallyl alcohols, including the synthesis of racemic ( )-nuciferol (45, equation 24) . Subsequently, other examples of nearly or completely stereospecific syntheses of ( )-) , y-substituted allylic alcohols have also been pub-lished - " . On the other hand, in the synthesis of y,y-disubstituted allylic alcohols a diminished stereoselectivity has been observed. In this case, the /Z ratio depends on the... 

The glass plate was exposed to microwave irradiation, eluted, and viewed by standard TLC visualization procedures to assess the results of the reaction. In this particular example, the synthesis of an arylpiperazine library (Scheme 4.25) was described, but the simplicity and general utility of the approach for the rapid screening of solvent-free microwave reactions may make this a powerful screening and reaction optimization tool. The synthesized compounds were later screened for their antimicrobial activity without their removal from the TLC plate utilizing bioautogra-phical methods [84],... 

Our strategy for the synthesis of a-hydroxylated lactone lignans might be extended to the general synthesis of a-hydroxylated lignans, when either of the alkylation steps is changed to an aldol addition. For example, berchemol... 

Ferrisilicate zeolites wherein iron ions replace silicon in the lattice framework have potential as catalyst in various conversion processes. During the past decade ferrisilicate analogs of sodallte, MFI, M, MTT, EUO, MTW, FAU, BETA, MOR and LTL have been synthesised and characterised by various physicochemical techniques as well as catalytic reactions. After a review of the general synthesis procedures a list of criteria is presented to confirm the location of Fe in the zeolite framework. Examples are provided to illustrate the utility of the various characterisation techniques. 

Abou-Gharbia and co-workersdescribed a general synthesis of 5,5-diphenyl-2-substituted-4(57f)-oxazolones as an extension of their earlier work. Reaction of diphenylketene with a series of A-acylsulhlimines lOa-d produced an intermediate A-acyl a-lactam that then rearranged to afford lla-d in 56-80% yield (Scheme 6.5). Examples are shown in Table 6.1 (Fig. 6.2). 

Electrochemical studies on V(II) complexes have been relatively few compared to the quantity of work on higher oxidation states. The recent discovery of a general synthesis has improved the availability of data on derivatives of vanadocene [15, 16]. For example, Ef values of L2V decrease in the order L = indenyl (—2.38 V versus Cp2Fe/TFlF)> Cp (—2.72 V versus... 

It should be pointed out that while the dihalocyclopropane-allene conversion discussed here represents the best general synthesis of allenes, occasional problems due to the formation of side products have been reported. An example is the formation of the bicyclobutane (16) along with the expected allene (equation 53).166 The method is especially unsuitable for the synthesis of tetrasubstituted allenes. Steri-cally demanding substituents on the dihalocyclopropanes are believed to be responsible for the change of course of the reaction. 

A new, efficient and general synthesis of 4-amino-3-arylcinnolines has been described recently, starting from arylhydrazines and aryl trifluoromethyl ketones, and the following is a typical example. Addition of a THF solution of the hydrazone formed from phenylhydrazine and 2-trifluoroacetylthiophene to 5 equivalents of KHMDS in THF at -78°C, then slow warming of the mixture to room temperature and stirring at room temperature for several hours, gave 4-amino-3-(2-thienyl)cinnoline in 68% yield after work-up (quench with ether, then a wash with brine). 

Reaction of vinyl sulfoxides with dichloroketene has been found to result in a new general synthesis of y-lactones. With phenyl ( >P-styryl sulfoxide, for example, the product, obtained in 65% yield, is the lactone 1. 

Allenic alcohols T reatment of the propargylic alcohol 1 with lithium aluminum hydride does not lead to the expected vinyl allenic alcohol 2 (3,99). However, addition of solid iodine to the intermediate aluminate does effect the desired elimination to give 2. This result was unexpected because addition of a solution of iodine in THF lends to a vinyl iodide (3). This sequence provides a general synthesis of (hydroxymcthyl)allcncs (second example). 

The use of metal ions as kinetic synthetic templates is extremely widespread, and is an excellent way in which to bring about the organisation of a number of reacting components in order to direct the geometry of the product. Because some metal ions, such as the transition metals, often have preferred coordination geometries (e.g. tetrahedral, square planar, octahedral etc), changes in metal ion may have a profound effect on the nature of the templated product. Metal-ion-templated syntheses may be classified more generally as examples of self-assembly with covalent postmodification. For example, the synthesis of the artificial siderophore 10.2 is effected by the use of an octahedral Fe3+ template.8 In this case, the macrobicyclic product is obtained as the Fe3+ complex from which it is difficult to separate. 

In addition to pyrolysis, transamination, and dehydrohalogenation with tertiary amines several other reactions have been described which yield access to the 1,3,2-diazaboracycloalkane system. For example, Abel and Bush 19> reported the ready replacement of silicon by boron in certain heterocyclic systems as illustrated in Eq. (6). It seems quite likely that this procedure can be developed into a general synthesis. On the other hand, the interaction of trialkylboranes with bis(l,3-diphenylimidazolid-... 

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