Lubineau’s green synthons - Carbohydrate Chemistry: Chemical and Biological Approaches - page 11

Lubineau's green synthons
Jacques Aug ´ * and Nad ` ge Lubin-Germain
DOI: 10.1039/9781849739986-00011
Some seminal contributions of Professor Lubineau in the field of water-promoted
reactions and glycochemistry are reviewed. Notably, three types of synthons, namely
a -hydroxy- g -lactones, glycosylamines and C -glycosyl compounds, can be regarded as
new tools in the hands of chemists or biochemists involved in green chemistry,
bioconjugate chemistry, glycochemistry or glycobiology, as evidenced by their
applications in many different fields.
1 Introduction
Organic synthesis using carbohydrates was the main thread of Professor
Lubineau works. His researches went from mechanistic and synthetic
advances in organic and glycochemistry up to interaction studies in
glycobiology. His contribution in cycloaddition reactions used as a new
way to produce mono- and oligosaccharides led him to initiate the first
asymmetric inductions by a grafted sugar. 1 After noting an analogy
between glucose and water structures, he highlighted the unique
physicochemical properties of water and pioneered organic reactions in
water. 2 Among the salient features in that field, we must cite the
convenient preparation in water of three green synthons, namely
a-hydroxy-g-lactones, glycosylamines and C-glycosyl derivatives (Fig. 1).
The greenness of these synthons, at least for two of them, was not
noticed by Lubineau when he has developed their synthesis, since green
chemistry was not yet the concept defined as ''the utilisation of a set of
principles that reduces and eliminates the use of hazardous substances
in the design, manufacture and application of chemical products''.
Today, modern chemical synthesis should be based upon the twelve
green chemistry principles. 3 The use of renewable materials such as
carbohydrates, which constitute 75% of the vegetal biomass is one of the
twelve principles. The atom economy is another salient feature since this
concept highlights the importance of the incorporation of all the atoms;
for a total synthesis it means that protection and deprotection of
carbohydrates should be avoided; if not, the global atom economy
dramatically decreases. This situation is worse when considering the
global reaction mass eciency and the global material economy. 4 These
metrics are proportional to the atom economy; the coecient of
proportionality depends on the yields, the excesses of reactants, the use
of auxiliaries, such as solvents which participate greatly to the waste. As a
matter of fact, the prevention of waste is the principle number 1 of green
chemistry. The importance of such prevention was emphasized as soon
as 1992 by Sheldon through the promotion of the E-factor defined as the