One-pot conditions

Hie reactions of 4-chloropyridines and quinolines 17 with benzotriazoles 18 in a modified Graebe-Ullman synthesis give excellent yields of Y arbolines and their benzo-fused derivatives 20. Excellent yields for preparation of the penultimate benzotriazole precursors 19 are reported as well. In the optimized one-pot conditions, the combined neat substrates are heated with microwave irradiation (MW) for short (7-10 min) durations. The crude 19 is treated with H4P2O7 and irradiated futher (4-6 min). The resultant y-carbolines 20 were methylated to form the quaternary salts. These were tested and found to lack DNA intercalation properties <96JOC5587>. 

Scheme 8.27 presents a highly stereoselective one-pot tandem 1,4-addition-ISOC for the construction of functionalized carbocycles. Addition of Grignard reagents to nitroalkenes and subsequent ISOC are carried out in one pot. The advantages of ISOC over INOC, namely, greater stereoselectivity and adaptability to one-pot conditions, have been demonstrated in Scheme 8.27.138... 

The main advantages of the GS/MW process are the rapid increase of temperature, the retention of organic molecules, and the possibility of performing some reactions under one-pot conditions. 

The fabrication of well-ordered arrays of well-defined nanoparticles or clusters is of fundamental and technological interest. As this is a difficult task, different techniques have been employed. An elegant approach would be to link well-defined building blocks in a chemically straightforward procedure yielding a monodisperse or a completely homogeneous material. We succeeded now to cross-link assembled nanosized metal-oxide-based clusters/composites - novel supramolecular entities - under one-pot conditions. 

S.9.7 Synthetic Applications. By the condensation of an ary-laldehyde in alkaline aqueous medium with an arylmethylketone followed by oxidation wiA hydrogen peroxide, 7- and 3, 4 -substituted flavonols were synthesized under one-pot conditions.An example is... 

Bromomalonate, selected as the pronucleophile, is proposed to undergo deprotonation by the diaryl prolinol catalysts lej to give the corresponding reactive enolate involved in the conjugate addition with different electron-poor alkenes (Scheme 7.9). The intramolecular alleviation proceeds with more nucleophilic indandione-derived enolate, under one-pot conditions, in... 

Applying the same two-step one-pot conditions to 4-SFs-anihne (11) and 1,1,1-trifluoroacetone, allowed one to obtain 2-CF3-5-SF5-indole (43) in 42% yield (Scheme 11). 

Mediated by CF3SO3H, ethynyl ketene-5,5-acetals 66 and 69, the highly reactive dienophiles can react in a one-pot condition with various arylamines and aldehydes, giving the corresponding quinolines in good yield via regiospecific aza-Diels-Alder reaction. ... 

A green one-pot preparation of nitroalkenes has been developed for example, ben-zaldehyde and nitromethane give pure nitrostyrene in 95% isolated yield in toluene, after 4h reflux (or 79% without toluene). A dual-catalyst system of iron trichloride and piperidine (both 10 mol%) simultaneously activates electro- and nucleophiles, without affecting many sensitive groups. The one-pot conditions can be extended by the addition of, for example, indole to give 3-alkylindole (74) via Michael addition of the initial nitrostyrene product. Similar one-pot tandem approaches yield 3-nitrochromenes and A-arylpyrroles. 

The third two-step version of the Gewald reaction allows the reaction of alkyl-aryl or cycloalkyl ketones which exhibit limited reactivity under the one-pot conditions, a >9-Unsaturated nitrile 9 as a product of Knoevenagel-Cope condensation is ahead prepared and isolated and then treated with sulfur and amine... 

The application of the one-pot conditions to (Z,Z)-substrate 199 was not as clean as the reactions of either 195 or 197 (Scheme 53). By subjecting 199 to a stepwise sequence where aminohydroxylation was followed by cyclization, the authors were able to conclude that the problematic step for the use of 199 was the oxidative cyclization to 201 rather than the aminohydroxylation to 200. Similar problems were found for the (Z, )-diene that corresponds to 199. 

Experimental data revealed that racemization rate (fRsa) decreases in the one-pot conditions indicated that the compounds present in the one-pot reaction sequence, particularly the esterified product, appear to inhibit the Ru(0FI)3/Al203 racemization catalyst. The amount of the enzyme catalyst is not influencing the racemization rate. 

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