852471-30-8

Upstream product

• 116228-40-1 4-iodo-1-[(4-methylphenyl)sulfonyl]-1H-pyrazole 
• 98-80-6 phenylboronic acid 
• 98-59-9 p-toluenesulfonyl chloride 
• 116228-41-2 4-bromo-1H-pyrazol-1-yl(4-methylphenyl)sulfone 

Downstream Products

• 10199-68-5 4-phenyl-1H-pyrazole 
• 457925-19-8 4-phenyl-1-[3-(phenylselanyl)propyl]-1H-pyrazole 
• 10183-74-1 withasomnine 

Relevant academic research and scientific papers

Direct synthesis of pyrazolo[5,1-a]isoindoles via intramolecular palladium-catalyzed C-H bond activation

An efficient, direct synthesis of pyrazolo-[5,1-a]isoindoles employing a palladium-catalyzed intramolecular C-H bond activation of 1-(2-halobenzyl) pyrazoles has been developed. The use of lithium chloride (LiCl) was found to be essential in these reactions, to suppress further C-H bond activation at the C-3 position of pyrazolo[5,1-a]isoindole, when C-3 is unsubstituted. This protocol can be applied to the synthesis of a pyrazolo[5,1-a]isoquinoline possessing a six-membered central ring system and a fully substituted pyrazolo[5,1-a]isoindole using sequential intra- and intermolecular C-H bond activation.

Bu3SnH-mediated radical cyclisation onto azoles

Alkyl radicals have been cyclised onto pyrroles, imidazoles and pyrazoles, and acyl radicals cyclised onto pyrroles, using Bu3SnH-, (TMS)3SiH- and Bu3GeH-mediated aromatic homolytic substitution for the synthesis of bicyclic N-heterocycles. The reactions yield intermediate π-radicals that lose hydrogen in the?rearomatisation step of the aromatic homolytic substitution. Mechanistic studies of these rearomatisation steps indicate aromatic homolytic substitution in which the initiator or breakdown products from the inhibitor are responsible for the H-abstraction step.

Pyrazolyl derivatives, preparation process and intermediates of this process as medicinal products and pharmaceutical compositions containing them

The present invention relates to the novel derivatives of formula (I) in which A is, if it is present, a (C1-C6) alkyl, a (C3-C6) alkenyl, a (C3-C6) alkynyl, a (C3-C7) cycloalkyl or a (C5-C7) cycloalkenyl, R1 is an NR6R7, (C4-C7) azacycloalkyl, (C5-C7) azacycloalkenyl, (C5-C9) azabicycloalkyl or (C5-C9) azabicycloalkenyl group; A-R1 is such that the nitrogen of R1 and the nitrogen in the 1-position of the pyrazole are necessarily separated by at least two carbon atoms, R3 is an H, halogen, OH, SH, NH2, ORc, SRc, SORa, SO2Ra, NHCHO, NRaRb, NHC(O)Ra, NHC(S)Ra or NHSO2Ra, R4 is an aryl or heteroaryl; and R5 is an H, halogen, CF3, CHF2, CH2F, linear or branched (C1-C6) alkyl or (C3-C7) cycloalkyl to their racemates, enantiomers and diastereoisomers and to their mixtures, their tautomers and to their pharmaceutically acceptable salts.

Radical cyclisation onto pyrazoles: Synthesis of withasomnine

A novel synthetic protocol for the synthesis of [1,2-b]-fused bicyclic pyrazoles has been developed using radical cyclisation. The protocol uses cyclisation of pyrazole-1-(ω-alkyl) radicals generated from 1-[ω-(phenylselenyl)alkyl]-pyrazole precursors. The pyrazole natural product, withasomnine (3-phenyl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole), and larger ring analogues have been synthesised in good yield using the protocol. A Bu3SnH-mediated oxidative cyclisation mechanism is facilitated by azo or Et3B radical initiators acting as oxidants of the intermediate π-radicals.