tert-Butyl isocyanide as a convertible reagent in Ugi reaction: Microwave-assisted preparation of 5,6-dihydropyrazolo[1,5-a]pyrazine-4,7-diones

Synlett

Volumn , Issue 2, 2009, Pages 260-262

  Nikulnikov, Mikhail ^a,b   Tsirulnikov, Sergey ^a   Kysil, Volodymyr ^c   Ivachtchenko, Alexandre ^c   Krasavin, Mikhail ^a,b  

^a Chemical Diversity Research Institute   (Russian Federation)

^b TULA STATE LEV TOLSTOY PEDAGOGICAL UNIVERSITY   (Russian Federation)

^c CHEMDIV INC   (United States)

Author keywords

Convertible isocyanides; Microwave assisted cyclization; Post Ugi MCR cyclization; Ugi multicomponent reaction

Indexed keywords

EID: 62349093669     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-108766     Document Type: Article

References (20)

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17. Other reaction conditions that were screened and proved inefficient for post-MCR cyclization of 3 included conventional heating in AcOH, conventional and microwave heating in TFA, as well as using base promoters (KOt-Bu, NaH) in various solvents (e.g., THF, DMF, dioxane). tert-Butyl isonitrile was chosen on the basis of its commercial availability in large quantities. However, we are also finding it superior to other isocyanides in the present post-MCR cyclization. These finding will be disclosed in a separate communication.
18. Parallel evaporation of volatiles from the microwave reactor tube was carried out using GeneVac® equipment.
19. No further purification and characterization (except LC-MS analysis) of the crude Ugi reaction products 3 were performed.
20. 2S: C, 65.50; H, 3.50; N, 10.47. Found: C, 65.54; H, 3.60; N, 10.51.