A simple synthesis of 1-aminophosphonic acids from 1-hydroxyiminophosphonates with NaBH4 in the presence of transition metal compounds

A new procedure has been developed for the synthesis of 1-aminophosphonic acids. Diethyl phosphonates are converted to hydroxyiminophosphonates when treated with hydroxylamine hydrochloride. Reduction of hydroiminophosphonates with NaBH4 in MeOH in the presence of MoO3 or NiCl2 and hydrolysis of 1-aminophosphonates gave 1-aminophosphonic acids in good yields.TBAG-1204 DPT-1995 AFP-1994NaBI-L/NiC12 1/2/5.T he mechanismo f the reactioni s uncertmnT. he substratee itherg ivesa complexw ith thet ransitionm etalc ompoundr,e ductionoc curringw ith theh ydrided onor,o r the reductiono ccursd irectlyw ith the transitionm etalh ydride.S omea dvantageofuesa tureso f our proceduraer e:( a) Startingm aterialasr ec heapa, ndt hee xperimentpalr oceduries verys imple(; b) 1-armnophosphonatceasn be obtainedi n one step; and (c) l-aminophosphonatmeas y be synthesizedw ithoutf ear of thermald ecompositioonf the hydroxyiminsou bstrate(.d ) This methodm ay be applicablet o large scale productiono f 1-aminophosphonataensd hence l-aminophosphonacicid s. Generaml ethodfo r thep reparatioonf O,O-diethy1l -aminophosphonaicci ds To a mixture of 1-hydroxyiminophospho(n1a0t em mol) and MOO3(15m mol, 1.5 equivalento) r NiCIz.6H20 (20 mmol,2 equivalenti)n distilledm ethano(l1 00 mL) was added carefullyN aBI-h(50 mmol,5 equivalent()e xothermirce action)a t ft. The resultingd arkc olored mixturew ass tirreda t ambientte mperatufroer 6h (checkebdy TLC; SilicaG el, EtOAc: Hexane) andt henf iltered.T he resultanmt ixturew asc oncentrateudn derr educedp ressure. The residue was treatedw ith aqueouKs OH (20%) and extracteds everatl imesw ith dichloromethanTeh. e aqueoulsa yerw ass aturatewd ith NaCI ande xtracteda gainw ith dichloromethanTeh. e combined organicla yerw erew ashedw ith watera nd againw ith brine,b eforeb eingd ried over MgSO4. Afterf iltrationa nde vaporatioonf solventt, he 1-aminod erivativew aso btainedas an oil. Further purificaUoni,f necessaryw, as achievedb y distillationu nderh igh vacuum.T o a mixtureo f hot ethano(l1 0ml) andO ,O-diethyll -aminophosphonacicid ( 1 mmol)w asa ddedp ropylenoex ide( 1 ml) with stirring.A fter the precipitationw as completet,h e analyticallyp ureaminophosphonic acidsw eref ilteredo f AcknowledgmenWtse: thank the Middle East TechnicalU niversityf or a grant( AFP-1994), Turkish StateP laningO rganizatiofno r a grant( DPT-1995),T urkish Scientifica nd Technical ResearchC ouncilf or a grant( TBAG-1204)