Table5.PredictedpurgefactorsforthionylchlorideinBAY43-9006process
stagereactivity(R)solubility(S)volatility(V)processesphysical
(PP)comments
110010101SOClproposition.2isavery
vacuum.ThionylAnalytereactiveintermediate(R=100),andthehighyields(89%)supportahighreactione ciency
chloridehashighboilssolubilityat79°Cin(DMFV=10).(S=There10),isandnointermediatephysicalprocessing5isisolated,inthiswashedstage(PPand=dried1).under
21001013SOClAnalyte2will
though,hasreact
isdissolvedhighwithsolubilitymethylamine
inethylinTHFbase
acetate(Sand=and10).with
washed/extractedThereaqueousisnospecibrine
with c(useddryingto
aqueousstepextract
brine(V=isolatedintermediate)(R=100).
(PP1).=The3).isolatedintermediate(7),
31001013SOCl2willreactwithbases(K-tert-butoxide/K2CO3)andwithaqueousbrine(usedtoextractisolatedintermediate)(intermediateR=100).Analyte(7),though,hashighisdissolvedsolubilityininethylDMFacetate(S=10).andTherewashed/extractedisnospeci cwithdryingaqueousstep(brineV=1).(PPThe=3).isolated4110101Reactivitysolubilityisinpredicteddichloromethanetobelow,(asSthe=10).reactionAnyisresidualperformedthionylinachloride,nonaqueousthough,environmentislikelyto(Rbe=1).removedAnalyteonhasdrying.ahighScheme2.SynthesisofGSK183390A
a
aReactionsconditions:(a)NaOEt,0 80°C,yield99%;(b)CH3NHNH2,EtOH,90°C,yield22%(unwantedisomeryield45%);(c)NHCHroomtemperature,yield93%;ethyl(d)ammoniumbromoisobutyrate,formate,yieldPd/C69%;catalyst,(h)TFA,re ux,CHMeOH,yield50%;(e)aqHBr,yield97%;(f)2OH·HCl,NaOAc,EtOH,Boc2O,2Cl2,Et3N,yield96%;(g)K2COthen3,DMF,Et2Cl2,yield82%;(i)NaOH,roomtemperature,yield98%;(j)SOCl2,toluene,80°C,3N,10,roomtemperature,yield96%;(k)NaOH,80°C,yield73%.
Table6.TheoreticalpurgefactorsforGTIsinPPARα/γagonist(1)syntheticprocess
GTIstagereactivityM=10,HL==100,1solubilityM=3,FL==10,1volatilityM=3,HL==10,1totalpermultiplestagerationaleforpurgefactor
CH3NHNH221001033000bpdistillation/partialofCH3NHNH288drying 90°C,solventremovedby
31339productisolatedanddried
410103300likelyformedreaction(stepwithj);productSO2Clandisolatedalsowithandthedriedacylchloride
ALL8.1×106
SO2Cl4(j)100101010000highlyreactive,volatilebp79°C
4(k)100101010000reactsinstantaneouslyinaqueousenvironment
1.0×108
(2-pyridyl)]-N-methylcarboxamide)(9)in87%yield.This(1)Methylhydrazineisusedinstage2tocyclisetheintermediate(9)isthencoupledwithisocyanate(10)toyielddiketone(4)toproducethepyrazoleester(5).theAPI(3).(2)Thionylchlorideisusedtoactivatethepyrazole(10)viaThebasisbywhichpredictedvaluesareselectedandthetheformationofanacidchloridewhichisthenreactedassociatedrationalesaredescribedinTable5.withthebenzylamine(10)toformtheAPI.Theoverallpurgefactoris9×10.12Theextremelyhigh
reactivityofthionylchloridetohighpH/aqueousconditionsApurgefactorassessmenthasbeenappliedtothisroutetodominatesthepurgingfactorinthe rstthreestages.determinethelevelofriskfromagenotoxicimpurities
3.2.CaseStudy2:RetrospectiveEvaluationofaperspectiveaspartofanevaluationofthepotentialcontinuedPPARα/γAgonist(GSK183390A).Thesyntheticschemeuseoftheproceduredescribed(Table6).
(Scheme2)showstheoriginalmedicinalchemistryrouteusedEmpirically,theriskofcarryoverofGTIs/PGIsisoftentomanufactureaPPARα/γagonistindrugdevelopment.Fromassessedonthebasisofproximity(pointofintroductioninthesynthesis)tothe nalAPI.Thus,thionylchloridetheoreticallyaGRAperspectivetherearetwoknowngenotoxiccompoundsposesthehighestriskwithrespecttocarryoverintotheAPIasinvolvedinthesynthesis:itisintroducedintothe nalcouplingstage.Inpracticethisis