Chemie von a‐Aminonitrilen. Aldomerisierung von Glycolaldehyd‐phosphat zu racemischen Hexose‐2,4,6‐triphosphaten und (in Gegenwart von Formaldehyd) racemischen Pentose‐2,4‐diphosphaten: rac‐Allose‐2,4,6‐triphosphat und rac‐Ribose‐2,4‐diphosphat sind die Reaktionshauptprodukte

Abstract

Chemistry of α‐Aminonitriles. Aldomerisation of Glycolaldehyde Phosphate to rac‐Hexose 2,4,6‐Triphosphates and (in Presence of Formaldehyde) rac‐Pentose 2,4‐Diphosphates: rac‐Allose 2,4,6‐Triphosphate and rac‐Ribose 2,4‐Diphosphate Are the Main Reaction Products Glyclaldehyde phosphate aldomerizes in aqueous NaOH solution to a product mixture containing the racemates of the two diastereoisomeric tetrose 2,4‐diphosphates and eight hexose 2,4,6‐triphosphates. At room temperature in the absence of air and after 7 days, a solution 0.08Min glycolaldehyde phosphate (=formylmethyl dihydrogenphosphate)and 2M in NaOH gives products, in up to 80% yield, with a tetrose/hexose derivative ratio of ca 1:10 and with rac‐allose, 2,4,6‐triphosphate comprising up to 50% of the mixture of sugar phosphates. When the reaction is run under the same conditions but in the presence of 0.5 mol‐equiv. of formaldehyde, sugar phosphates are formed in up to 45% yield, with pentose 2,4‐diphosphates now predominating over hexose triphosphates by a ration f 3:1 rac‐Ribose 2,4‐diphosphate is found to be the major component, the ratios am ribose, arabinose, lyxose, and xylose 2,4‐diphosphates being 52:14:23:11 in a representative experiment. The pentose diphosphates are constitutionally stable under the reaction conditions (observed for 23 weeks), but the diastereoisomeric ratios slowly change with time (tc 22:34:30:14 after 23 weeks), showing that ribose 2,4‐diphosphate is not the thermodynamically favored di…