Cyclohexyl analogue

Until now, only a few effective ligands of this type have been identified (Fig. 25.4). Kagan and co-workers [5] prepared one of the few chiral diphosphines with only planar chirality and obtained 95% ee for the hydrogenation of DM IT with LI (Table 25.1, entry 1.1.), but enantioselectivities for several enamide derivatives were below 82% ee (the best results were with the cyclohexyl analogue of LI). For the reactions with DM IT or MAC, the cationic Rh-kephos complex showed comparable or better performance than corresponding duphos catalysts. 

Seem, R. C., H. Cole, Jr., and N. L. Lacasse. Suppression of ozone injury to Phaseolus vulgaris Pinto III with triarimol and its monochlorophenyl cyclohexyl analogue. Plant Dis. Rep. 56 386-390, 1972. 

A. Cyclohexyl Analogues Are Phenyl Groups Necessary for Anticancer... 

Table 1. Microtubule Disassembly Inhibitory Activity and Cytotoxicity of Cyclohexyl Analogues 16-18 and 20...

The in vivo antitumor activities of 23a and 23d were evaluated against B16 melanoma in B6D2F1 mice.39 Taxoids (0.4 mL/mouse) were administered intravenously (i.v.) on days 5, 7, and 9. Results are as follows for 23a, T/C = 5% (20 mg/kg/day), time for median tumor to reach 1000 mg (days) = 26.03, log10 cell kill = 1.97 for 23d, T/C = 8% (12.4 mg/kg/day), time for median tumor to reach 1000 mg (days) = 27.54, log10 cell kill = 2.25. The results clearly indicate that, unlike the cyclohexyl analogues, both analogues are very active in vivo and their activities are equivalent to that of docetaxel in the same assay. 

The cyclohexyl analogue was prepared by addition of isothiocyanate 7 to the six-membered aminocyclitol hydrochloride 434 to give the adduct 435, which was treated... 

However, not everyone was convinced by the existence of the non-classical carbocation. H. C. Brown 1977 pointed out that the norbornyl compounds are compared with cyclopentyl rather than with cyclohexyl analogues, 2.21 (eclipsing strain), and in such a comparison the endo-isomev is abnormally slow, the exo-isomer being only 14 times faster than cyclopentyl analogues. He also pointed out that the formation of racemic product is due to two rapidly equilibrating classical carbocation species (Scheme 2.17). The interconversion of enantiomeric classical carbocation species must be very rapid on the reaction timescale. 

Finally, ortho effects involving the radical cations of various nitro-substituted alkylphe-nols are mentioned here. In these cases, two sequential ortho effects have been observed. For example, the El mass spectra of 2-ethyl-4,6-dinitrophenol and its 2-cyclohexyl analogue exhibit pronounced peaks for the formation of [M — H20] + and [M — H2O — OH]+ ions and the spectrum of 2-isopropyl-4,6-dinitrophenol even indicates that the secondary fragmentation step is faster than the primary one, because an ion abundance ratio [M — H2O - OH]+/[M - H20] + = 25 was found . 

The last member of the family [NbCl(Tp )(c-CnH2n-i)] (n = 3-6) has been also recently reported [NbCl(c-C4H7)(Tp )(MeC=CMe)] is similar to cyclopentyl and cyclohexyl analogues, and very different from the cyclopropyl derivatives. The cyclobutyl complex exhibits an a-C-H agostic interaction in the dominant isomer, with no evidence for the a-C-C agostic character found for the smaller ring that seems to be unique for the cyclopropyl complex.41... 

Of these, the most practical commercially would be the one based on amides. Terephthalamide (easily made from inexpensive dimethyl terephthalate) and its cyclohexyl analogue have been converted to isocyanates via N chloro compounds (2.25).65... 

O Brien (1971) pointed out that the majority of insecticidal carbamates are aromatic, suggesting the involvement of n-n interactions in binding them to the enzyme. Thus compound 7 is about 1000 times as active as its cyclohexyl analogue. 

Branching of the hydrocarbon chain near the basic nitrogen atom is unfavourable. The cyclohexyl analogue for instance is significantly less potent than the corresponding cyclohexylmethyl and cyclohexylethyl derivatives (Table 11). 

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