Regio- and diastereoselective preparation of tetrahydrobenzo[c]-1-aza-2lambda(5)-phospholes through dearomatization cyclization of lithiated N-benzyl-N-alkyl(diphenyl)phosphinamides. Synthesis of gamma-(N-alkylamino)phosphinic acids.
A study of the protonation of the cycloadducts derived from the dearomatization reaction of lithiated N-alkyl-N-benzyldiphenylphosphinamides has been carried out. The regio- and stereoselectivity of the process has been analyzed in terms of the size of the N-alkyl substituent, the acidity and size of the protonating reagent, and the cosolvent used. The optimization of these variables allowed the preparation of tetrahydrobenzo[c]-1-aza-2lambda(5)-phospholes containing a 1,3-cyclohexadiene or 1,4-cyclohexadiene system with moderate to excellent regio- and stereocontrol. The heterocycles were readily hydrolyzed, affording gamma-(N-alkylamino)diphenylphosphinic acids with the functionalities linked to a cyclohexadiene substructure.
Fernández
Ignacio
I
Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento, 04120 Almería, Spain.
Ortiz
Fernando López
FL
Velázquez
Amador Menéndez
AM
Granda
Santiago García
SG
D000577:Amides / Q000737:chemistry; D001372:Aza Compounds / Q000737:chemistry; D003500:Cyclization; D006540:Herbicides / Q000138:chemical synthesis / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010721:Phosphinic Acids / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000577:Amides; D001372:Aza Compounds; D006540:Herbicides; D009943:Organophosphorus Compounds; D010721:Phosphinic Acids; D008094:Lithium