Aryl derivatives analogs

Alkyl and 6-aryl derivatives of 3,5-dioxo-2,3,4,5-tetrahydro-l,2,4-triazine or of its thio analogs have been mentioned before in this review (e.g., Section II,B,2,a). Some of theih contained functional... 

This chapter covers recent information on the preparation, physical properties, and reactions of quinoxaline and its C-alkyl, C-aryl, iV-alkyl, and A-aryl derivatives as well as their respective ring-reduced analogs. In addition, it includes methods for introducing alkyl or aryl groups (substituted or otherwise) into quinoxalines already bearing substituents and the reactions specific to the alkyl or aryl groups in such compounds. For simplicity, the term alkylquinoxaline in this chapter is intended to include alkyl-, alkenyl-, alkynyl-, and aralkylquinoxalines likewise, arylquino-xaline includes both aryl- and heteroarylquinoxalines. 

The Si NMR chemical shifts for several Tg derivatives are shown in Table 2. The alkyl derivatives fall in the range —54 to —57ppm, while the aryl derivatives are more upheld from —66.9 to —68.9 ppm, as expected for aryl versus alkyl substituents. Bassindale et al. have derived a relationship, = 0.82 x Tg/ allowing an estimation of the chemical shift for unknown Tg derivatives from the known values for the much more common Tg analogs. The solid-state Si NMR spectrum for Tg[OSiMe3]g shows five signals for the silsesquioxane silicon atoms. 

Benzamides constitute a fourth dass of HDAC inhibitors. One example, MS-275, is a phenylenediamine derivative that exhibits robust HDAC inhibition in patients with advanced myeloid leukemia as well as refractory solid tumors or lymphoma in Phase I studies [72]. MS-275 is currently in Phase II trials. In a recent study aimed at optimizing the benzamide scaffold, several bis-(aryl) type analogs were synthesized and evaluated for their activity against a panel of HDACs [85]. Moradei et al. found that a thienyl substitution para to the free amino group in the phenylenediamine core rendered inhibitors specific for HDACsl, 2 with potency superior to that of MS-275. Isoform-specific inhibitors should aid in dissecting the roles of HDACs in normal cellular fundioning and cancer. 

Similarly to their 2-aryl-substituted analogs <1996CHEG-II(6)301>, 2-methyl- and 2-benzyl-5-phenyl-l,3-oxazine-4,6(57T)-diones 26B proved to be less favored tautomers than the corresponding 4-hydroxy-l,3-oxazin-6-ones 26A in (003)280. H NMR measurements showed the ratio of the tautomers 26A and 26B to be 55 45 for the 2-methyl- and 60 40 for the 2-benzyl-substituted derivative <2005ARK(xv)88>. 

Alkenyl and alkynyl R4Pb and RePb2 compounds tend to be less stable thermally than alkyl analogs. Furthermore, they also exhibit poorer hydrolytic stability and stability to air. Thus, tetravinyllead is sensitive to water. The failure to successfully isolate tetraallyllead may be as much due to its hydrolytic and air instability as to its thermal instability. Alkyl and aryl derivatives which are substituted extensively with fluorine atoms also tend to be hydrolytically unstable, particularly... 

In common with everyone else at that time, I believed that the transition metals formed no alkyl or aryl derivatives, except perhaps analogs of the mysterious phenylchromium compounds, and the alkyl-bromogold compounds, e.g., AuEt2Br and AuEtBr2, which had been formulated as halogen-bridged compounds (III or IV) (47). 

The bismuthonium ylides (45, X = CH2,0) react with aryl or alkyl aldehydes to give a variety of products, depending on the ylide, the aldehyde (RCHO) and the conditions. The products include cyclopropane derivatives (46), furan derivatives analogous to 46 but with a furan ring replacing the cyclopropane ring, and in some cases (from 45, X = O and... 

Any pattern of nomenclature for the complex hydrides should be capable of extension to the complex alkyl and aryl derivatives. The last two examples indicate how this is accomplished. In strict analogy the alkyl groups should be designated methylo, ethylo, etc., but this may depart too much from custom and imply too definite a conviction as to the nature of the carbon-metal bond. 

The aromatic ring in the "address" portion of naltrindole and its analogs is important for antagonist activity at 8 receptors. The tetra-hydroindole derivate is much less potent, as are several 6-aryl derivatives (195). The 7(.E)-benzylidine analog of naltrexone, 7-benzyli-denenaltrexone (BNTX, 44, Fig. 7.8), however, is a potent 8 antagonist (193,342). It has... 

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