Prato reaction

Prandtl mixing length hypothesis, 11 779 Prandtl number, JJ 746, 809 13 246-247 Praseodymium (Pr), J4 631t, 634t electronic configuration, J 474t Praseodymium bromide, physical properties of, 4 329 Prater equation, 25 270, 299 Prater number, 25 299, 300-301, 303 effect on maximum dimensionless intrapellet temperature, 25 304, 309 effect on maximum intrapellet temperature, 25 306 Prato reaction, 12 244 Pratsinis aluminum nitride, 17 212 Pravachol, 5 143... 

Scheme 15 Reaction of Cgo with azomethine ylide the Prato reaction...

The Prato reaction was also found to take place in the solid-state reaction. Thus, the reaction of Cgo with J -methyl- or i -ethylglycine in the presence of paraformaldehyde or with various substituted benzaldehydes was examined under the HSVM conditions (1 h), and was found to give a moderate yield (20-30%) of fulleropyrrolidine 37 together with around 50% recovery of Cgo (Scheme 16) [47]. The effect of the molar ratio of the reagents was examined in detail and a C6o glycine aldehyde ratio of 1 1 1 to 1 2 2 was found to be optimum. 

Scheme 16 Solid-state Prato reaction of Qo under HSVM conditions...

Table 4.8 Porphyrin aldehydes subjected to the Prato reaction with sarcosin.

Further donors, mainly based on aniline or ferrocene, were subjected to the sarcosin-based Prato reaction. The bisaldehydes 224 [260] or 227 [250] react with two CgQ-molecules, leading to dumbbell shaped dimers (Table 4.9). The Cgo dimer obtained from 224 could be considered as an A-D-A triad but the CV-data indicate that the dimer behaves electrochemically as two independent donor-acceptor units. 

Figure4.12 TTF and extended TTF was attached to C q via the Prato-reaction in order to get dyads suitable for long-lived charge-separated states.

Fulleropyrrolidines bearing one or two TFMPO-groups have been synthesized via the Prato reaction [289, 290]. The biradical adduct 248 was formed by condensation of the corresponding TEMPO aldehyde 246 and the TEMPO-functionalized amino acid 247 (Scheme 4.39) [289]. Probably due to steric hindrance, the yields of this reaction are modest. 

For the formation of 15 (Figure 6.9) a different mechanism has been proposed [62]. Reaction of singlet oxygen with the corresponding amine (iminodiacetic methylester) leads - after two H-abstractions - to an azomethine ylide as a key intermediate. This ylide can add to the double bond via a [3-i-2]-cycloaddition related to the Prato reaction (Section 4.3.4). 

The synthesis and characterization of the first N-tritylpyrrolidino derivative of Sc3N Cyg utilizing the Prato reaction was successfully produced in 2007 (Cai et al. 2007). On the basis of NMR spectra and DPT calculations, Cai and coworkers concluded that the two monoadducts obtained corresponded to the addition to two different type B [6,6] bonds (called c-f and b-d). The X-ray diffraction of one of the obtained compounds (c-f addition) confirmed that the 1,3-dipole was attached to a [6,6] bond (Cai et al. 2007). It is interesting to remark here that the cyclopropanation reaction of Sc3N C7g and diethyl bromomalonate yielded one mcmoadduct and one dominant symmetric bisadduct, which corresponded to the same type B [6,6] addition (Cai et al. 2008). The photochemical addition reaction of adamantylidene to Lat Cyg was produced on both a [6,6] and a [5,6] bond (Cao et al. 2008). 

Fig. 25.7 Covalent functionalization of sp -hybridized carbons (a) Diels-Alder reaction (b) Prato reaction (c) diazo-nium chemistry (d) alkylation of graphene oxide/activated graphenes (e) azidation halogenations (g) nitrene addition and (h) Bingel reaction (Reprinted with permission from Schaetz et al. 2012, Copyright 2012 American Chemical...

Perfluorinated BSubPc bearing axial m-formylphenoxy group 196 [99] was used for preparation conjugates with fullerene (Scheme 51) as tunable molecular scaffolds for intramolecular electron and energy transfer processes [110]. The azome-thine ylide formed by treatment of the formyl derivative 196 with A -methylglycine gives the conjugate with fullerene 197 (44 %) in a dipolar 1,3-cycloaddition (Prato reaction). 

Fulleropyrrolidines are synthesized through the addition of azomethine ylides as 1,3-dipolar compounds to fullerene (Scheme 3.7). This reaction is known as the Prato reaction. There are several methods of generating azomethine ylides. In the Prato reaction, a decarboxylation route is employed with the use of easily available aldehydes and a-amino acid derivatives. Both starting materials undergo dehydrative condensation to give 5-oxazolidinones, which generate azomethine ylides with elimination of CO2. Azomethine ylides react with Cgo and produce fulleropyrrolidines in moderate yields. 

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