Organic chemical simulation of synthesis

In 1969 Corey and Wipke [7] reported the program OCSS (Organic Chemical Simulation of Synthesis) which was the precursor of one of the most powerful programs known at present which has been named LHASA (the acronym of Logic and Heuristics Applied to Synthetic Analysis) [5b] [8]. Since then, different... 

The computer-assisted synthetic analysis designated OCSS (organic chemical simulation of synthesis) and LHASA (logic and heuristics applied to synthetic analysis) were designed to assist chemists in synthetic analysis by Corey et LHASA generates trees of synthetic intermediates from a target molecule by analysis in the retrosynthetic direction. 

The chemical simulation of this biosynthetic process has been developed as an important methodology in organic synthesis. Van Tamelen reported the add-catalyzed cyclization of chiral terminal epoxides of polyprenoids [11]. In contrast, Johnson adopted the acid-catalyzed cyclization of poly-prenic acetals derived from chiral diols [12]. In addition to these pioneering studies, the biomimetic polyene cycliza-tions of polyprenoids, which are induced by a variety of electrophiles such as proton, oxonium ion, halonium ion [13], or metal ion [14], have also been developed. Despite extensive studies on these diastereoselective olefin cyclizations, enantioselective processes using synthetic chiral catalysts had not been developed for a long time. In 1999, Yamamoto s... 

It is of course surprising that amino acids can be obtained via the Strecker synthesis, purines from the condensation of HCN, pyrimidines from the reaction of cyanoacetilene with urea, and sugars from the autocatalytic condensation of formaldehyde. The synthesis of chemical constiments of contemporary organisms by non-enzymatic processes under laboratory conditions does not necessarily imply that they were either essential for the origin of life or available in the primitive environment. However, the significance of prebiotic simulation experiments is... 

The area between enzymatic and chemical catalyses, associated with simulation of biochemical processes by their basic parameters, is accepted as mimetic catalysis. The key aspect of the mimetic catalyst is diversity of enzyme and biomimetic function processes, which principally distinguishes the mimetic model from traditional full simulation. Based on the analysis of conformities and diversities of enzymatic and chemical catalysis, the general aspects of mimetic catalysis are discussed. An idealized model of the biomimetic catalyst and the exclusive role of the membrane in its structural organization are considered. The most important achievements in the branch of catalysis are shown, in particular, new approaches to synthesis and study of biomimetic catalase, peroxidase and monooxidases reactions. 

The design of a complex reaction mechanism can also be helped by the computer. This is obviously very close to that of the organic synthesis assisted by the computer, which has given rise to an abundant literature (see, for example, refs. 228—233 and references therein). Studies dedicated to organic synthesis are not concerned with the problems of the kinetic modelling and simulation of reactions and reactors. Only two investigations directed towards chemical kinetics will be briefly mentioned. 

On the other hand, some studies on shock-induced devolatilization produced results inconsistent wiOt the above conclusion. Mukliin et al. [70J examined tlie effect of laser-pulse heating on meteorite materials and silicates in order to simulate the vaporization that occurs during impacts and to stud the chemical composition of the gases produced. The experimental results showed tliat the residual gas mixture consisted of both oxidized and reduced components CO, CO2, SO2, H2O, H2, N2, H2S, COS, CS2, various hydrocarbons from Ci to Ce, HCN, and CH3CHO. They emphasized that the gas mixtures formed by vaporization of silicates provide favorable conditions for abiotic synthesis of organic materials. 

Organic Chemical Synthesis Simulation (OCSS) - This landmark programll effectively removed the barrier between chemist and computer by the use of interactive computer graphics the chemist could communicate with the machine for the first time in the language of structural diagrams. 

Supercritical water (SCW) presents a unique combination of aqueous and non-aqueous character, thus being able to replace an organic solvent in certain kinds of chemical synthesis. In order to allow for a better understanding of the particular properties of SCW and of its influence on the rate of chemical reactions, molecular dynamics computer simulations were used to determine the free energy of the SN2 substitution reaction of Cl- and CH3C1 in SCW as a function of the reaction coordinate [216]. The free energy surface of this reaction was compared with that for the gas-phase and ambient water (AW) [248], In the gas phase, an ion-dipole complex and a symmetric transition... 

Corey EJ, Wipke WT, Cramer RD, Howe WJ (1972) Computer-assisted synthetic analysis. Facile man-machine communication of chemical structure by interactive computer graphics, J Am Chem Soc 94/2 421 Wipke WT, Braun H, Smith G, Choplin F, SieberW (1977) SECS — Simulation and evaluation of chemical synthesis Strategy and planning, in Computer-assisted organic synthesis, Wipke WT, Howe WJ ed, ACS Symposium Series, p 98... 

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