Phosphorus Pentoxide in Organic Synthesis, XXIX. Synthesis of 4‐Arylamino‐5,6,7,8‐Tetrahydro‐1 H ‐Pyrazolo[3,4‐ b ]Quinolines and the Corresponding N‐Mannich Bases | Zendy

Nielsen Søren V. | Zendy; Pedersen Erik B. | Zendy

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Phosphorus Pentoxide in Organic Synthesis, XXIX. Synthesis of 4‐Arylamino‐5,6,7,8‐Tetrahydro‐1 H ‐Pyrazolo[3,4‐ b ]Quinolines and the Corresponding N‐Mannich Bases

Author(s) -

Nielsen Søren V.,

Pedersen Erik B.

Publication year - 1986

Publication title -

liebigs annalen der chemie

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.825

H-Index - 155

eISSN - 1099-0690

pISSN - 0170-2041

DOI - 10.1002/jlac.198619861006

Subject(s) - chemistry , cyclohexanone , phosphorus pentoxide , yield (engineering) , formaldehyde , reagent , dehydrogenation , hydrochloride , mannich reaction , medicinal chemistry , organic chemistry , catalysis , materials science , metallurgy

4‐Arylamino‐5,6,7,8‐tetrahydro‐1 H ‐pyrazolo[3,4‐ b ]quinolines 2 have been synthesized from ethyl 5‐amino‐1 H ‐pyrazole‐4‐carboxylate ( 1 ) and cyclohexanone by heating in a reagent mixture of P 4 O 10 , N,N ‐dimethylcyclohexylamine, and an appropriate arylamine hydrochloride (8 – 52% yield). Reaction of 2 with formaldehyde and secondary amines afforded the Mannich bases 3 in 45 – 94% yield. Attempts to prepare the 5,6,7,8‐dehydrogenated analogues of 2 using a previously adopted method failed.

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