Step economy organic synthesis

One of the fundamental aspects in Green Chemistry is linked to the number of steps in organic synthesis as well as atom economy. Multicomponent reactions (MCR) are thus becoming a more and more important class of reactions since they allow combining several starting materials in usually a single compound and in a one-flask operation. 

As a result of the minimal substrate protection required, metathesis allows to design synthesis routes that are (unprecedentedly) short and therefore meet the demands for an economy of steps as a prime criterion of contemporary organic synthesis (33). 

During the last decade, molecular ruthenium catalysts have attracted increasing interest for organic synthesis due to their ability to perform specific new reactions with a large panel of applications. Beside individual catalytic transformations, a variety of multi-step catalytic transformations in one pot have appeared. These transformations present practical and economic advantages as far as they are efficient, selective and proceed with atom economy. Ruthenium catalysis has entered this field with a variety of cascade and sequential catalytic transformations. 

INTRODUCTION AND BACKGROUND 1.1 Step Economy in Organic Synthesis... 

FIG. 1 Strategies to improve step economy in organic synthesis. 

Clarke, P. A., Santos, S., Martin, W. H. C. (2007). Combining pot, atom and step economy (EASE) in organic synthesis, synthesis of tetrahydropyran-4-ones. Green Chemistry, 9, 438-440. 

These great challenges, however, also provide a number of opportunities for organic chemists to think how to improve the effieiency of a chemical synthesis. The efficiency can be simply evaluated from the overall yield and the overall number of synthetic transformations. If the yield of every transformation is considered as the same, the shorter synthetic sequences for the targeted natural product, often referred to as step economy, can be considered as the most important conceptual framework of an efficient synthesis. 

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