UNIVERSITA’ DEGLI STUDI DI MILANO PhD IN CHEMICAL SCIENCES XXII CYCLE Daniele Sergio ZERLA Matr. R07227 Tutor: Chiar.mo Prof. E.CESAROTTI Histidine and deuterium labelled histidine by asymmetric catalytic reduction

Natural Amino Acids AlaCysHisMetThr ArgGlyIlePheTrp AsnGlnLeuProTyr AspGluLysSerVal Amino Acids obtainable by catalytic hydogenation AlaIleLeuPheTyr Χ Cat* Rh(I) H2H2

Histidine Carnosine L- Carnosine: endogenous dipeptide (b-alanyl-L-Histidine) presents in the human muscles and nerve tissue. It has the ability to react with toxic aldehydes deriving from metabolic pathway of oxidative degradation of endogenous compounds and so it has a protective and detoxifying effect on the toxic metabolites. D- e L- Carnosine: used for the preparation of a medicament or diet supplement for the treatment or prevention of disorders induced by oxidative stress which are characterized by the formation of cytotoxic carbonyl compounds in the body. These disorders are neurodegenerative ones like Alzhheimer’s, Parkinson’s and ALS, diabetes and the complications thereof, atherosclerosis, age-associated tissue degeneration, sarcopenia, nephropathy, vascular dysfunction, hypertriglyceridemia, hypercholesterolemia, hypertension in metabolic syndromes.

RYield % Ph75 Boc-β-Ala0 CH 3 0 Only when ippuric acid is used we have the azlactone and than the corresponding dehydro amino acid If the pharmacological results are encuraging the next target is synthesize and deuterate some derivates of dehydro- histidine characterized by substituted imidazolyl ring, in order to study the pharmacological property of the corresponding carnosine derivatives.

[PP(Rh)COD] + ClO 4 - MeOH H 2 HBF 4 Catalystacid Sub/ acid Time (h) Yielde.e.% (S,S)-(+)-DIOP// 240 (R,R)-(-)-Me-DUPHOSHCl1/11200 (R,R)-(-)-Me-DUPHOS// 1206 %N.D. (S,S)-(+)-DIOP// %5.5 (R,R)-(-)-Me-DUPHOS// %25 (R,R)-(-)-Me-DUPHOSHBF 4 1/2120/6645/63 %86,1 (R,R)-(-)-Me-DUPHOSHBF 4 1/ %80,9/100 (S,S)-(+)-DIOPHBF 4 1/ %15,4 (R)-ProlophosHBF 4 1/ %70,3 (S,S)-BDPPHBF 4 1/ %67,6

[PP(Rh)COD] + ClO 4 - Solv. HBF 4 D 2 + Solv.S/CCatalyst Time (h) Yielde.e.%DH % MeOH1000/1(-)MeDUPHOS7212n.d.40 MeOH200/1(-)MeDUPHOS ,727 MeOD200/1(-)MeDUPHOS ,10 MeOH200/1R-PROLOPHOS ,975 MeOD200/1R-PROLOPHOS72 69,311

[PP(Rh)COD] + ClO 4 - Solv. HBF 4 D 2 + Solv.acidCatalystYielde.e.% DH % MeOH-(-)Me-DUPHOS MeOD-(-)Me-DUPHOS MeOHHBF4(-)Me-DUPHOS MeODHBF4(-)Me-DUPHOS MeOH-R-PROLOPHOS MeOD-R-PROLOPHOS MeOHHBF4R-PROLOPHOS MeODHBF4R-PROLOPHOS100794

The presence of monodeuterated product is due to the competition between reductive elimination and protonation/hydrolysis on the σ-deutero-Rh-alkyl- intermediate.

We found the best condition for hydrogenation and deuteration of dehydro- histidine, however we can’t synthesize the dehydro-carnosine to go straightforward to carnosine with asymmetric reduction; we has synthesized labelled D-histidine as precursor of non natural carnosine using for “in vivo” pharmacological studies. Study other strong acid like HClO 4, CH 3 SO 3 H, CF 3 SO 3 H(D) as additives and determining their activity on yield, e.e. and percentage of monodeuterated product. Synthesize other derivates of dehydro-histidine characterized by substituted imidazolyl ring.