Application scheme

Fig. 61 Application scheme according to the data pair method — Vj to V3 = standard solutions, U] to U3 = sample solutions...

Fig. 7 Linomat C (Camag) for on-line transfer of column eluate fractions to TLC/HPTLC plates (A) and application scheme (B).

It is also interesting to note that the in situ use of some bis-imidazolium salts allowed the presence of several common oxidants in the reaction medium and the possibility to work in open-air vessels, a result of significant relevance to indnstrial applications (Scheme 6.10) [48]. 

The nonacarbonyldiiron-induced transformation of oxazabicyclo[2.2.2] octenes (12) into condensed azetidinones is intriguing mechanistically but will obviously have limited synthetic application (Scheme 15).37 The /(-lactam (14a), among other products, is isolated directly from the iron carbonyl reaction but the dimethyl analog (14b) is obtained by pyrolysis of an isolable intermediate <7-7r-allyl complex (13b). 

Phthalocyanines 244 and hemiporphyrins 245 and 246 are aromatic systems. Extended conjugation confers special properties to these molecules that make them building blocks for new molecular organic materials with useful electric and nonlinear optical applications (Scheme 85).288... 

Among the best known and most versatile hosts are the various cydodextrins [1,2] of which a-, P- and y-cyclodextrins are the most available. These are cyclic oligosaccharides built up of six, seven, or eight glucopyranose units, respectively. These compounds can be prepared by enzymatic hydrolysis of starch. The undoubtedly most important member of the cyclodextrin family is P-cyclodextrin (P-CD) which has become a cheap and easily available chemical, suitable for large scale applications. Schemes... 

For instance, Kochi and co-workers [89,90] reported the photochemical coupling of various stilbenes and chloranil by specific charge-transfer activation of the precursor donor-acceptor complex (EDA) to form rrans-oxetanes selectively. The primary reaction intermediate is the singlet radical ion pair as revealed by time-resolved spectroscopy and thus establishing the electron-transfer pathway for this typical Paterno-Biichi reaction. This radical ion pair either collapses to a 1,4-biradical species or yields the original EDA complex after back-electron transfer. Because the alternative cycloaddition via specific activation of the carbonyl compound yields the same oxetane regioisomers in identical molar ratios, it can be concluded that a common electron-transfer mechanism is applicable (Scheme 53) [89,90]. 

Subsequent development of this general approach was directed to the in situ formation of ions 14 from various precursors. As a result, a series of three-component one-pot syntheses of salts 16 has been created. The reactions of aldehydes with nitriles or amides to form amidoalkyl ions 14 are most applicable (Scheme 2) (70JAP70/24582 71S92 74G1181). The... 

The zirconium-promoted addition of diethylzinc to an alkynybrinc derivative is also possible,102,103 and allows for several interesting synthetic applications (Scheme 37).104... 

Suitably substituted tropylium salts offer an alternative to condensation with active methylene compounds (cf. Section IV,A,4,c) even if the application of tropones fails. Thus, 6-chloro derivative 266c (82CB3756) or thioether 605 (Scheme 163 91KGS1432) were used to get, respectively, sesquifulvalenes and heptafulvene 606. O-Functionalized compounds are likewise applicable (Scheme 110 cf. 73CRV293, p. 308). 

Figure 2 shows the separation of bromophos-ethyl and dimethoate on an HPTLC pre-coated plate silica gel 60 (left) and on an HPTLC pre-coated plate RP-18 (right). The application scheme was the same in both cases, namely from left to right ... 

The most recent method developed for the nA —> An approach relies on dynamic covalent bond formation using a metathesis reaction. In this case, reactions are typically under thermodynamic control, providing the potential for increased selectivity in product formation. The initial examples using alkyne metathesis toward the formation of SPMs were reported by Adams, Bunz, and coworkers using the precatalyst [Mo(CO)6] [27,28], but rather low yields of the desired products (4) limited general applicability (Scheme 6.2). Recent efforts by Moore and coworkers using a Mo(VI)-alkylidyne catalyst, however, have refined this process such that precipitation-driven reactions now provide moderate to excellent results (see Scheme 6.24) [29]. 

This reaction was used for the in situ generation of a base upon irradiation, a process of significance in imaging applications (Scheme 13.10) [38],... 

The aim of this technique is precisely the same as DPV Fig. 10.14 shows the pulse application scheme. The form of the voltammograms (peaks) was deduced theoretically19. As in DNPV, the great advantage is the reduction in time during which electrolysis occurs. 

Transmetalation of the allyllithium intermediates allowed access to the cuprate manifold of reactivity. The rapid construction of a linear triquinane, 229, using this methodology demonstrates the potential for synthetic application (Scheme 70). 

It is important to recall that the reactivity pattern of phosphoies is very different from that of the related S, N, and O ring systems due to their limited aromatic character. For example, electrophilic substitution takes place only with a handful of phosphoies that have been specifically tailored via increasing the bulkiness of the P substituent (see Section 3.15.10.4, Scheme 83). In fact, electrophiles react at the phosphoms atom affording a panel of neutral and cationic CN 4 derivatives (Scheme 8). Phosphoies are also versatile synthons for the preparation of other heterocyclic systems via Diels-Alder reactions. The cycloaddition can involve the dienic moiety of the phosphole ring or can occur following a 1,5-shift of the P-substituent (Scheme 8). Finally, phosphoies can be transformed into phospholide ions, which are powerful nucleophiles that have found a variety of applications (Scheme 8). All these facets of phosphole reactivity are presented in this section. It should also be noted that CN 3 phosphoies exhibit a rich coordination chemistry toward transition metals (see Section 3.15.12.2). 

Provided that a reasonable and useful product profile (see Table 2, above) has been established, the general aim of the project and the most relevant objectives have already been decided. As with most research projects, these will most likely address the efficacy, this time with more qualifications concerning the exact indication, the type of product, its formulation and application scheme. 

With the turn of the century, new products with broad-spectrum activity comparable to the best azoles are entering the market (trifloxystrobin, pyraclostrobin). To find their share in the already highly sophisticated application schemes and developed markets, they need to be presented to the customer as complete, broad-spectrum products, preferably incorporating anti resistance tools. In many instances suspoemulsion formulations will be a cornerstone to combine all required pieces of today s fimgicidal armory in one product. 

The preparation of acid azides from thiocarboxylic acids/HNa or from acyl chlorides with dibenzyldi-methylammonium azidosulfonate has not yet found broad application (Scheme 42). 

Automatic scanning instruments are usually coupled to integrators or the integration is carried out by built-in microprocessors. With computer integrators, the user is tied to the application scheme provided by the integrator (arrangement of standards and samples on the plate). At times this scheme is not the most suitable one for the thin-layer chromatography. 

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