[Current status and prospect of DNA synthesis in industrial biotechnology].

DNA synthesis is one of the most basic, widely-used tools in life science as well as a key enabling technology in synthetic biology. The rapid development of industrial biotechnology promoted by synthetic biology is creating an insatiable demand for large-scale DNA synthesis from more convenient, economical and safe sources. Industrial DNA synthesis platforms have remarkable advantages in terms of throughput, cost and speed.

MASSIS: a mass spectrum simulation system. 2: Procedures and performance.

The use of the mass spectral simulation system, MASSIS, is reported and its performance has been evaluated. The search for substructures matching with fragments stored in four pivot databases was realised using the Ullmann algorithm. Special cleavage rules, such as the McLafferty rearrangement, the retro-Diels-Alder reaction, elimination of a neutral small molecule and oxygen migration, are processed through shortest path and depth-first search algorithms.

3-deoxy-3,3-difluoro-D-arabinofuranose: first stereoselective synthesis and application in preparation of gem-difluorinated sugar nucleosides.

The design and synthesis of gem-difluorinated sugar nucleosides were described. The key intermediate, 3-deoxy-3,3-difluoro-d-arabinofuranose 9, was first stereoselectively prepared from the chiral gem-difluorohomoallyl alcohol 12. The kinetic formation of single anti-14 in the benzylation of 12 could be accomplished by controlling the amount of sodium hydride used.

MASSIS: a mass spectrum simulation system 1. Principle and method.

A mass spectrum simulation system was developed. The simulated spectrum for a given target structure is computed based on the cleavage knowledge and statistical rules established and stocked in pivot databases: cleavage rule knowledge, function groups, small fragments and fragment-intensity relationships. These databases were constructed from correlation charts and statistical analysis of large population of organic mass spectra using data mining techniques.

On the 6-exo atom transfer radical cyclization reactions of 3-butenyl 2-iodoalkanoates.

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3.OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53-71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations.