Ketosulfones cyclic

Potassium salts of cyclic ketosulfones of various size 310 (n = 6, 8, 12) reacted with phenyl (Z)-l-propenyl selenone affording cyclic ketosulfones 311 of various ring sizes (n + 1) having a vinyl group at the 3-position391. 

For example, it was reported in several independent articles that multicomponent treatment of 5-amino-3-methylpyrazles with 1,3-cyclohexandiones and aldehydes under refluxing in EtOH [82, 83], in DMF with methanol [84], or with application of continuous-flow microwave-assisted procedure in DMSO [85] yielded exclusively pyrazoloquinolinones 50 (Scheme 23). On the other hand, the treatment of 3-unsub-stituted 5-aminopyrazoles with cyclic p-diketones or ketosulfones gave mixtures of Hantzsch dihydropyridines 51 and Biginelly dihydropyrimidines 52 in different ratios [86]. 

The reaction of the a,5-dianion of the cyclic ketosulfone with dichloroisobutene results in formation of the bridged [3 + 4]-type cycloaddition product in good yield (Scheme 20)32. 

Ketosulfones like (117) and (118) are readily alkylated and acylated. The alkylation may occur either at carbon or at oxygen depending on the reaction conditions (Scheme 51). Furthermore, one-pot alkylation using suitable dihaloalkanes occurs to yield cyclic products such as the cyclopropyl sulfone (119), as shown in Scheme 51. 

Anilide 2a catalysed asymmetric intramolecular Michael reaction of formyl enones to chiral cyclic keto-aldehydes in excellent yields with good stereoselectivity (eqn. (1) in Scheme 6.3). The intramolecular Michael addition of a ketosulfone to an unsaturated ketone (eqn. (2) in Scheme 6.3) catalysed by 15e has heen used as a key step in the synthesis of the carbon tricyclic framework of Lycopodine. The same sulfonylprolinamide served as catalyst in the construction of all-carhon substituted quaternary stereocentre via Robinson-type annulation process (eqn. (3) in Scheme 6.3). 

Conceptually, the acetone component could be replaced with any carbonyl conqmund containing an adjacent methylene groi which will undergo enamine formation. Carbonyl variations, iriiich we found to readily undergo this reaction widi 4-chloroaniline and BTF in dry acetonitrile, are aliphatic linear, branched and cyclic ketones, pyruvates, P-ketoesters, P-ketosulfones and 1,3-diones. Biacetyl did not provide product under these conditions. Aldehydes and acetophenones required pre-formation of the enamine intermediate prior to BTF addition and tended to proceed in lower yields. Eighty exanqiles were chosen to test steric, electronic and lipophilic properties. In cases where the carbonyl conqionent was unsymmetrical and could produce two isomeric enamines, multiple dihydropyridine products were formed. 

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