N-protected/N-substituted-beta-amino hydroxy sulfonates

A process of stabilizing for storage an N-protected/N-substituted alpha-amino aldehyde comprising:

• (a) treating the N-protected/N-substituted alpha-amino aldehyde represented by the formula:
• wherein R1 represents alkyl, alkenyl, alkyl substituted with one or more aryl radicals, cycloalkenylalkyl, alkanoyl, haloalkanoyl, aroyl, alkoxycarbonyl, aralkoxycarbonyl, heteroaralkoxycarbonyl or 9-phenylfluoren-9-yl radicals;
• R2 represents hydrogen, alkyl, alkenyl, aralkyl, cycloalkyl, cycloalkenylalkyl or aryl radicals;
• or −NR1R2 represents heterocyclo or heteroaryl radicals;
• and
• R3 represents alkyl, haloalkyl, cyanoalkyl, hydroxyalkyl, alkoxyalkyl, aryloxyalkyl, alkylthioalkyl, arylthioalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, cycloalkyl or cycloalkylalkyl radicals;
• or
• R2 and R3 together with nitrogen atom and the carbon atom to which they are bonded form a heterocyclo radical;
• with HSO3W at an equivalence ratio of about 1:1 to about 1:10 in a mixture of water and an organic solvent to form a corresponding stable N-protected/N-substituted beta-amino hydroxy sulfonate;
• wherein the organic solvent is selected from the group consisting of ethyl acetate, tetrahydrofuran, isopropyl acetate, methyl isobutyl ketone, methyl ethyl ketone, acetone, dimethoxyethane, dimethoxymethane, dioxane, and methyl tert-butylether;
• the N-protected/N-substituted beta-amino hydroxy sulfonate represented by the formula:
• wherein W represents a cation which is capable of forming a sulfate salt;
• and R1, R2 and R3 are as defined above;
• and
• (b) converting the N-protected/N-substituted beta-amino hydroxy sulfonate back to the N-protected/N-substituted alpha-amino aldehyde by (i) treating the N-protected/N-substituted beta-amino hydroxy sulfonate with an aqueous base solution at a pH of between about 7.5 to about 10 and (ii) extracting with an organic solvent.