Furyl groups

Throughout this paper Fu stands for a 2-furylic group, /. ... 

Silanes with heterocyclic residues were also found to be reactive (Equation (20)), although the most likely reason is the in situ cleavage of the heterocyclic residue in the presence of hydrated TBAF to form silanols.290-292 Similarly, among various arylgermanes, only those containing 2-furyl groups were reactive in cross-coupling reactions.293... 

Insertion of thienyl or furyl groups into alkyllead compounds can be carried out using organolithium reagents. Thus, organolead(IV) tricarboxylates can be prepared as follows via tin(IV) precursors ... 

The electronic character of aromatic groups at the a-C of nitrones affects both, the yields and the stereoselections (Table 2.28). Electron-rich aromatic groups increase enantioselectivities but decrease the yields (entries 1-3). Electron-deficient ones slightly decrease enantioselectivities but increase the reaction rates (entries 4 and 5). The electronic properties of A-bound aromatic groups of nitrones has almost no obvious impact on the enantio-selections (entries 6-10). Both, electron-deficient and electron-rich aromatic groups afford good enantioselectivities and diastereoselectivities. Nitrone with a A-bound furyl group furnishes, in moderate yield, the best ee but the lowest diastereoselectivity (entry 9). a-Alkyl and A-alklyl nitrones fail to react (entries 11 and 12). 

Italian workers have reported extensive studies on the evaluation of a values for thienyl and furyl groups. These are collected in Table XII. The am, Om, and am values reveal the electron-withdrawing inductive effect of the rings, while as expected from the previous discussion of this section, these substituents fall into that small category whose op, oj>, and Op values are all different, revealing an ability to both accept and donate electrons by resonance under the appropriate incentives. 

TABLE 3. Photoproducts and yield from the photolysis of the furylated group 14 catenates in cyclohexane ... 

Mannich reaction of the piperidine derivative (30) with 3-formylfuran gave a mixture of the four stereoisomeric quinolizidin-2-ones, cf. (31). The major product [as (31), but with a /3-furyl group] was isomerized with base to the most stable ftms-quinolizidinone (31), which on Wolff-Kishner reduction afforded a mixture of alkaloids (27) and (21). 

Azetidines having a 4-methoxyphenyl, styryl, or 2-furyl group at C(2) and a benzyl or allyl substituent on nitrogen, when exposed to diethylaluminium chloride, give alkenes, stereoselectively through a fragmentation process (Scheme 29) <1999JOC9596>. 

The 2-furyl group has been characterized as a substituent in classical Hammett-type studies involving the ionization of substituted benzoic acids, the ionization of substituted phenols, and the solvolysis of 1-arylethyl acetates. The a values found (<7 +0.06, dp +0.02 +0.11, [Pg.402]

The fatigue resistance was improved when the furyl group was replaced with indole or oxazole [29, 30]. The coloration/decoloration cycles of oxazolyl fulgide 26 could be repeated more than 500 times in toluene, even in the presence of oxygen. The fatigue resistance strongly depends on the aryl groups. 

Table XV gives values of the constants for 5-substituted 2-thienyl and 2-selenienyl groups (70G777), the a constants for the 5-substituted 2-thienyl groups (65RTC1169), as well as the and constants for 5-substituted 2-furyl groups (74CCC1711 77CCC105).

To calculate the ffp constants for 5-substituted 2-furyl groups Fisera et al. used the pX, values of substituted benzoic acids (34) with 5-substituted 2-furyl... 

The ffm constants for 5-substituted 2-furyl groups have been estimated from the pX, values for furylpyridinium cations (35) (77CCC105). Equation (30) was used to calculate the constants (64JCS3591). 

Figure 1 Example of colorless adducts and colored purple pigments detected in model solution containing (-fepicatechin (Rj= H, R2= OH) or (+)-catechin (Rj- OH, R2= H), malvidin 3-0-glucoside and acetaldehyde (R= CH3), glyoxylic acid (R= COOH), furfural (R-furyl group),...

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