Heterocyclics spiroheterocyclics

A mixture of Meldrum s acid or barbituric acid derivatives, urea and aldehyde gave 99, stereoselectively. Reaction of 2-methylene indoline derivatives with l-nitroso-2-naphthol gave 100. Spiroheterocycles 101 were prepared from a mixture of isatin and aromatic or heterocyclic... 

Isatin-3-imines 822 are versatile precursors for the synthesis of spiroheterocycles. They were prepared by grinding together an equimolar mixture of isatin and aromatic or heterocyclic amine. Subsequent treatment with mercaptoacetic acid using inorganic supports such as montmorillonite KSF, alumina, or silica gel in an open vessel upon MWI gave spiro compounds 823 within 5-7 min. The montmorillonite KSF is the best solid support, giving the best yields (92-97%) in the shortest time and easiest work-up (Scheme 156) (030PP401). 

A triethylamine-catalyzed MCR with isatin 241 to synthesize a spiroheterocycle 243 in excellent yield was reported by Kumar and Arya (Scheme 6.35) [68], Eighteen different spiro-heterocycles were synthesized using this method with variation of the diketone 241 and the 2-aminobenzothiazole 242. 

M.l. Emmanuel, L.L. Frye, E.R. Hickey, W. Liu, T.M. Morwick, D.M. Spero, S. Sun, D.S. Thomson, Y.D. Ward, E.R.R. Young, Novel spiroheterocyclic compounds [morpholine-4-carboxylic acid amides of heterocyclic cyclohexylalanine and neopentylglycine derivatives and their analogs], useful as reversible inhibitors of cysteine proteases such as cathepsin S, PCT Int. Appl. 2001 (2001) 361pp W02001019816. 

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