One-Step Synthesis of Substituted 3,5-Dicyanospiro-4-(piperidine-4^′)-1H,4H-dihydropyridine-2-thiolates and 2,6-Diamino-3,5-dicyanospiro-4-[(piperidine-4′) or (2′-oxoindole-3′)]-4H-thiopyrans

Abstract

A new, one-step method for the synthesis of substituted 3,5-dicyanospiro-4(piperidine-4′)-1H,4H-dihydropyridine-3-thiolates and 2,6-diamino-3,5-dicyanospiro-4-[(piperidine-4′) or (2′ -oxoindole-3′)]-4H-thiopyrans using a multicomponent reaction of N-substituted piperidine-4-ones and isatins with derivatives of cyanoacetic acid is described. The regioselectivity of this reaction can be controlled by varying the substituents at the nitrogen atom of the piperidine-4-ones. The multicomponent reaction of N-alkylpiperidine-4-ones with malononitrile and cyanothioacetamide gives spiro-4-(1′ -alkylpiperidine-4′)-1H,4H-dihydropyridine-2-thiolates, whereas a similar reaction of N-(acyl)alkoxycarbonylpiperidine-4-ones leads exclusively to spiro-4-(1′ -(acyl)alkoxycarbonylpiperidine-4′)-4H-thiopyrans.

Keywords:

• Cyanothioacetamide
• malononitrile
• multicomponent reaction
• spiroheterocycles
• thiopyrans

Dedicated to Professor Marian Mikołajczyk, CBMiM PAN in Łódź, Poland, on the occasion of his 70th birthday.

We thank the Presidium of the Russian Academy of Sciences (P-8, 2007) for partial financial support of this work.