Exploratory Investigations Probing a Preparatively Versatile, Pyridinium Salt Photoelectrocyclization−Solvolytic Aziridine Ring Opening Sequence

Abstract

A novel pyridinium salt photoelectrocyclization-nucleophilic bicyclic aziridine ring opening reaction sequence has been investigated in order to determine its preparative potential. N-Alkylpyridinium perchlorates were found to undergo photoinduced electrocyclization upon irradiation in nucleophilic solvents, such as H(2)O and MeOH, to efficiently produce 6-alkyl-6-azabicyclo[3.1.0]hex-2-en-4-yl alcohols and ethers. The bicyclic aziridine photoproducts react with a number of different nucleophiles (e.g., H(2)O, MeOH, AcOH, AcSH) under acid-catalyzed conditions to produce 5-(nucleophile-substituted)-4-(alkylamino)cyclopenten-3-yl alcohols and ethers. The aziridine ring opening processes are both regioselective and stereoselective, yielding trans,trans-trisubstituted cyclopentenes exclusively, apparently as a consequence of the operation of an SN(2) mechanism. The effects of C-alkyl substitution on the regiochemistry of the pyridinium cation photocyclization reaction were briefly probed, and a method was developed to produce trans,cis-trisubstituted cyclopentenes by use of this tandem preparative sequence.

An Expeditious and Green Approach for the Synthesis of 2-Amino-4h-Chromenes Using a Catalyst of Natural Origin

“…6-8. Some among them are extremely effective against such kind of diseases which influenced by nitrogen-activated protein kinase enzyme inhibitors. Some of them have antimicrobial activity , 11 cytotoxic effect against human cancer cells, 12 antiallergic activity, 13 central nervous system influencing activity, 14 antiproliferation activty. 15 Several derivatives are also widely used as agrochemicals, 16 antioxidant 17 and antiinflammatory agent.…”

An Efficient Conversion of Alcohols to Alkyl Bromides Using Pyridinium Based Ionic Liquids: A Green Alternative to Appel Reaction

“…An elegant procedure for the conversion was reported wherein triphenylphosphine and tetrahaloalkanes were used [2]. Other notable synthetic procedures are the Mitsunobo reaction [3], the reaction of 2,4,6-trichloro- [1,3,5]-triazine (TCT) in DMF followed by addition of CH2Cl2 solution of the reactant alcohol [4], the reaction of alcohol with 2,3-trichloro-5,6-dicyanobenzo-quinone in the presence of triphenyl phosphine, CH2Cl2 and a phase transfer catalyst [5]. ROMP-gel supported triphenyl-phosphine [6], phosphorus(V) mediated nucleophilic substitution reaction [7] and finally the use of fluorous phosphine [8] besides others.…”

Synthesis and characterization of new 1H-pyrazolo[3,4-b]pyridine phosphoramidate derivatives

“…[1][2][3][4] Substituted pyrazolo [3,4-b]pyridines represent a very important building block in organic synthesis and numerous studies have been reported due to their well-documented biological activity. [5][6][7][8] Several 4-substituted pyrazolo [3,4-b]pyridines have been obtained by our group through nucleophilic substitution of the 4-chloro precursor with variable nucleophiles and showed antileishmanial, 5 antiviral 9 and antibacterial 10,11 promise. It is known that coupling molecules with well-established pharmacological activities might be a good strategy to develop new significant products.…”