SUCROSE AS A RENEWABLE ORGANIC RAW-MATERI AL - NEW, SELECTIVE ENTRY REACTIONS VIA COMPUTER-SIMULATION OF ITS SOLUTION CONFORMATIONS AND ITSHYDROXYL GROUP REACTIVITIES

This account describes the application-oriented development of novel, highly selective and practicable ''entry reactions'' for the derivatiz ation of sucrose, utilizing modem molecular modeling procedures, which allow the realistic simulation of the preferred conformation in proti c (water) and aprotic solvents (DMF, pyridine) as well as the differen t reactivities of the eight hydroxyl groups. Due to the persistence, i n DMF solution, of a hydrogen bond between the glucose and fructose po rtions, of the type 2g-O ... HO-1f and 2(g)-O ... HO-3(f), two conform ations are preferred, of which the MOLCAD-generated electrostatic pote ntial (MEP) proves the 2(g)-OH the by far most electropositive, i.e. t he most acidic one and, hence, the one to be deprotonated first. This insight was transferred into practicable chemistry: deprotonation of s ucrose in DMF with base (1 molar equiv.) and quenching the monoalkoxid e with benzyl bromide generates 2(g)-O-Benzyl-sucrose (> 80%) - a new entry reaction that made readily accessible a series of 2(g)-modified products: 2-deoxy-sucrose, sucrosamine, sucrose-2,3-epoxide, and enant iopure dihydropyranone, all compounds with industrial application pote ntial. - An entry into glucosyl-C-4-modified sucroses is possible via pivaloylation to the 4(g)-OH-free heptapivaloate (> 50%) which through oxidation, oximation, reduction, and beta-elimination provides a simi lar set of new application-profiled products. - Another, highly select ive entry reaction for the chemical modification of sucrose, and alrea dy realized on an industrial scale, is the enzymatically induced 2(f)- O-->6(f)-O-glucosyl shift to isomaltulose - a transformation, that on the basis of molecular modelings can be readily understood as a closed shell process. Being more easily derivatizable than sucrose, isomaltu lose is readily converted into products with industrial application pr ofiles: air-oxidation generates glucosyl-alpha(1-->5)-arabinonic acid, reductive amination isomaltamine, each being convertible in one more step - amidation with fat-amines or N-acylation with fatty acids - int o products with interesting detergent and liquid crystal properties; a cidic dehydration transforms isomaltulose into glucosyloxymethyl-furfu ral (alpha-GMF) in a surprisingly uniform reaction, which - like its p arent compound HMF - is amenable to various ensuing reactions, e.g. to alpha-GMF-acrylic acid esters, that, on polymerization, are apt to pr ovide new, biologically degradable polymers.