Substituted alkylketo compounds and process

#The present invention concerns a stereoselective enzymatic reductive amination process.

#Robl in U.S. Pat. No. 5,508,272 disclose compounds of the formula

#wherein A is

#FIG. 1. Plasmid pET-15b. The sequence is numbered by the pBR322 convention. Sequence landmarks include T7 promoter at 453-469; T7 transcription start at 452; His Tag coding sequence at 362-380; T7 terminator at 213-259; pBR322 origin at 3882; and bla coding sequence at 4643-5500.

#FIG. 2. Plasmid pET-9b.

#FIG. 3. Plasmid pPICZ A,B,C. Features include 5′ AOX1 promoter region at 1-942; 5′ end of AOX1 mRNA at 824; 5′ AOX1 priming site at 855-875; Multiple cloning site at 932-1011; myc epitope tag at 1012-1044; polyhistidine tag at 1057-1077; 3′ AOX priming site at 1160-1180; 3′ end of mRNA at 1251; AOX1 transcription termination region at 1078-1419; fragment containing TEF1 promoter at 1420-1831; EM7 promoter at 1832-1899; Sh ble ORF at 1900-2274; CYC1 transcription termination region at 2275-2592; ColE1 origin at 2603-3276.

#In the above formulas the monovalent cation can be, for example, lithium, potassium, sodium, ammonium, and the like. It is preferred that R1 is hydrogen, ammonium, lithium, or potassium; and that R2 is a dioxolane moiety of the formula

#It is also preferred that R3 is lower alkyl, especially methyl.

#The most preferred reductive amination process of the invention comprises the conversion of 5-(1,3-dioxolan-2-yl)-2-oxo-pentanoic acid to 5-(1,3-dioxolan-2-yl )-2S-amino-pentanoic acid (L-allysine ethylene acetal) by reductive amination which is depicted below: