ChemInform Abstract: Chemoselective Cyclocondensation of α‐Acylacetamidines with 2‐Methylsulfanyl‐4,6‐dichloropyrimidine‐5‐carbaldehyde.

Abstract

Fused pyrimidine derivatives R 0515Chemoselective Cyclocondensation of α-Acylacetamidines with 2-Methylsulfanyl-4,6-dichloropyrimidine-5-carbaldehyde. -(RYAZANOV, S. G.; SELIVANOV, S. I.; DAR'IN, D. V.; LOBANOV, P. S.; POTEKHIN, A. A.; Russ. J. Org. Chem. 44 (2008) 2, 288-291; St. Petersburg State Univ., St. Petersburg 198904, Russia; Eng.) -A. Forchert 01-169

Competitive formation of condensed azines and dihydropyridines in the reaction of ethyl 3,3-diaminoacrylate with o-halo carbaldehydes

“…However, it also agrees with our proposal that it is the product of oxidation of the secondary intermediate, most likely formed after addition of one molecule of the enediamine carbon nucleophilic center to the formyl group and cyclization by addition of the amino group to position 4. The aldehyde 11 reacts with the same chemoselectivity as the chloropyrimidinecarbaldehyde 2 [2] and, in fact, the carbon nucleophilic center takes part in the stage of aromatic nucleophilic substitution of the halogen and the nitrogen atom of the enediamine forms a bond with the formyl group. This result confirms the proposal that the effect of the two ortho substituents is to hinder the approach to the formyl group and this determines the reaction course despite the lowered activity of the ring.…”

“…Aldehyde 11 reacts with the enediamine 3 by the same route as its analog -4,6-dichloro-2-methylsulfanylpyrimidine-5-carbaldehyde (2) [2]. Only the single pyrido[4,3-d]pyrimidine product 12 was separated.…”

“…The reaction of aldehyde 7a with enediamine 3 gave the benzo[c] [2,7]naphthyridine 8a in 77% yield. Its NOESY correlation spectrum showed strong cross peaks between the signal for the methylene in the carbethoxy fragment and the H-10 proton doublet (7.97 ppm).…”

“…In our recent study of the reaction of α-acylacetamidines (which exist in solution in the tautomeric enediamine form) with 2-fluoro-5-nitrobenzaldehyde (1) and 4,6-dichloro-2-methylsulfanylpyrimidine-5-carbaldehyde (2) the main reaction products are isoquinolines and pyrido [4,3-d]pyrimidines respectively [1,2]. α-Acylacetamidines react as C,N-dinucleophiles.…”

Cyclocondensation of 3,3-diamino-1-phenylpropenone with pyridine and quinoline N-oxides containing an electrophilic group in position 3

“…In reactions with aromatic aldehydes and esters containing an active halogen atom in the ortho position studied in our previous work [5][6][7], benzoylacetamidine acts as a C,N-dinucleophile. The reactions with aromatic dielectrophiles are chemoselective: the carbon nucleophilic site replaces the halogen atom in the ring, while the amino group reacts with the exocyclic electrophilic group.…”