Rapid synthesis of tetrahydro-4H-pyrazolo[1,5-a]diazepine-2-carboxylate

Tetrahedron Letters

Volumn 44, Issue 31, 2003, Pages 5867-5870

  Cvetovich, Raymond J ^a   Pipik, Brenda ^a   Hartner, Frederick W ^a   Grabowski, Edward J J ^a  

^a MERCK RESEARCH LABORATORIES   (United States)

Author keywords

Aminohydrazines; Hydroxyhydrazines; Pyrazole formation; Pyrazolo diazepine

Indexed keywords

ALCOHOL DERIVATIVE; AMINE; CARBOXYLIC ACID DERIVATIVE; DIAZEPINE DERIVATIVE; DICARBOXYLIC ACID DERIVATIVE; OXAZEPINE DERIVATIVE; OXAZINE DERIVATIVE; PROPRANOLOL DERIVATIVE; PYRAZINE DERIVATIVE; PYRAZOLODIAZEPINE; PYRAZOLOOXAZEPINE; PYRAZOLOOXAZINE; PYRAZOLOPYRAZINE; TETRAHYDRO 4H PYRAZOLO[1,5 A]DIAZEPINE 2 CARBOXYLATE; UNCLASSIFIED DRUG;

ARTICLE; CRYSTALLIZATION; ISOLATION AND PURIFICATION; POLYMERIZATION; QUANTUM YIELD; SYNTHESIS;

STAPHYLOCOCCUS PHAGE 3A;

EID: 0038645674     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(03)01417-5     Document Type: Article

References (15)

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8. 5: C, 54.77; H, 6.27; N, 5.81. Found: C, 54.73; H, 6.27; N, 5.74.
9. NMR and analytical data for compounds 2b-f can be found in Supplementary Data. The supplementary data is available online with the paper in ScienceDirect.
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15. Methyl 4-oxo-5,6,7,8-tetrahydro-4H-pyrazolo[1,5-a][1,4]diazepine-2-carboxylate ( 4b ). Enaminoketone 5 (1.22 g, 5.0 mm) was dissolved in methanol (10 mL) and added 3-hydrazino-1-propylamine bis-Tosic acid salt ( 7k ) (2.22 g, 5.1 mm). 2N aq HCl (0.5 mL) was added and the mixture was stirred 8 h. This was partitioned between methylene chloride (20 mL) and aq bicarbonate (20 mL). The aqueous phase was extracted with methylene chloride (3×20 mL), and the extracts were evaporated to solids (0.80 g). The solids were dissolved into acetonitrile at 60°C and DBU (10 μl) was added to complete cyclization. After evaporation, lactam 4b was isolated and found to be identical to known lactam. Additional experimental, NMR and Analytical data for compounds 3a,b, 4a, 8, 9, and 10 can be found in the Supplementary Data.