Reaction synthesis strategy

Developing a suitable synthesis strategy for a target compound by searching for synthesis precursors, starting materials and synthesis reactions... 

The key step in Biichi s total synthesis of loganin (5i)23 made use of the expansion of a four-membered ring to an oxygen-containing heterocycle by retro-aldol reaction. This strategy was later exploited by Tietze in his total synthesis of hydroxyloganin (54) as well as hydroxyloganic acid (55) 24). 

To fully use the advantages afforded by multicomponent reaction systems in solid-phase organic synthesis, strategies in which each component is immobilized on the resin must be devised. In this way, individual components can be explored in terms of diversity without the restrictions imposed by immobilization. We have described solid-phase Mannich reactions1 of a resin-bound alkyne (see chapter 5), and we show here that the diversity of products using this chemistry can be enhanced when a different component of the reaction system is immobilized. Specifically, a secondary amine, piperazine, is bound to a resin and then treated with... 

A key aspect of any synthesis strategy on a polymeric support is the linkage element, which acts as a tether to the polymeric support. Ideally, the linker should be stable to all reaction conditions used in a synthesis sequence and should be cleaved quantitatively under conditions that do not degrade the desired target molecule [6]. In this overview the different kinds of linkers and the synthetic transformations that can be used on polymeric supports will be presented. At the end, synthetic strategies for the synthesis of heterocycles and natural products will be mentioned. 

A multicomponent reaction/cyclization strategy was employed to synthesize simplified cyclopeptide alkaloid analogues 82. The enamide double bond found in many natural derivatives is missing, but biologically active cyclopeptide alkaloids with a hydrated enamide double bond (like sanjoi-nine G1 [55, 56]) are known. The synthesis is considerably simplified by omitting this unsaturation, obviously not required for biological activity. 

Going over the basics and mechanisms of nucleophilic substitution reactions Mastering mechanisms of elimination/addition reactions Determining synthesis strategies for aromatic systems... 

The first column of each month is devoted to a total synthesis. So many outstanding total syntheses appear each year, no attempt was made to be comprehensive. Rather, each synthesis chosen was selected because it contributed in some important way to the developing concepts of synthesis strategy and design. It is important to note that even if a total synthesis was not featured as such, all new reaction chemistry in that synthesis was included at the appropriate place in these Highlights. 

Recently, the discovery of polymerase chain reactions (PCR) by K. B. Mullis [4] in 1985 clearly demonstrates that in vitro , abiotic construction of DNA in a flask by these genealogical directed synthesis strategies is presently a routine and significant commercial process. These genealogically directed syntheses lead to an extramolecular proliferation of molecular level progeny. 

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