4669-69-6Relevant academic research and scientific papers
PHOSPHORORGANISCHE VERBINDUNGEN 96. DIE SELECTIVE VERKNUEPFUNG BIOLOGISCH WICHTIGER FUNKTIONELLER GRUPPEN MIT PHOSPHORORGANISCHEN SAEUREN
Horner, L,Gehring, R.
, p. 157 - 176 (2007/10/02)
Derivatives of phosphinic, phosphonic, and phosphoric acids of the general type R1R2P(O)X show selectivity in their reactions with nucleophiles RYH (R = n-C4H9; Y = O, NR or S) according the Eq. (1); the selectivity depends on the nature of the leaving group (X = Cl, F, CN, N3 or OC6H4NO2(p)) and the base used.The nature of the ligands R1 and R2, exert a comparatively minor influence on the reaction.Method: (a) The phosphylating agent R1R2P(O)X was allowed to react with mixture of two nucleophiles RYH and RY'H in competition (Reagent ratio 1:1:1).The product mixture (R1R2P(O)YR + R1R2P(O)Y'R was then analyzed. (b) Compounds of the type HY-CH2-CH2-Y'H (serine-n-butylamide L-cysteinmethylester) were reacted with the phosphylating agent R1R2P(O)X (reagent ratio 1:1) according the Eqs. (3) and (4) respectively.The products were isolated, identified and the yields quantitatively determined.Results: For X = F, CN, OC6H4NO2 (p), the O-ester is formed virtually exclusively.For X = Cl, only amides are formed.Azides (X = N3) show no selectivity.In competition reactions using n-butylamine and n-butylthiol, the organophosphorus chlorides (X = Cl) were found to be N-selective,, whereas the corresponding cyanides (X = CN) were S-selective.In competition reactions using n-butanol and n-butylthiol, the organophosphorus fluorides (X = F) p-nitrophenylesters (X = OC6H4NO2(p)) and cyanides (X = CN) were all O-selective.
Preparation of 3-substituted cephalosporins
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, (2008/06/13)
There is described a process for preparing an enamine of formula (IX): STR1 where R2 is a carboxylic acid protecting group and R3 is the residue of a carboxylic acid derived acyl group and where R5 and R6 are the same or different C1-4 alkyl or C7-10 aralkyl groups; or taken together with the adjacent nitrogen atom form a heterocyclic ring containing from 4 to 8 carbon atoms and optionally a further heteroatom selected from oxygen and nitrogen; by reacting a compound of formula (XII): STR2 with an amine of formula HNR5 R6, the reactant of formula (XII) being prepared by reaction of an appropriate enol derivative with a phosphorus reagent. The enamines of formula (IX) are useful in the preparation of 3-hydroxycephalosporins.
