ABSTRACT
There is a growing need for more sustainable approaches to the
manufacture of fine chemicals for pharmaceutical and agrochemical
agents.1 Of particular note is the challenge associated with the
manufacture of chiral chemicals in an environmentally sound
way. Traditional approaches to the asymmetric synthesis of chiral
compounds often involve the use of resolving agents, stochiometric
chiral reagents (e.g., chiral hydrides), auxiliaries, or catalysts
dependent upon chiral ligands and heavy metals such as rhodium
and ruthenium. The use of such reagents to induce asymmetry in
a molecule is not truly sustainable, and such processes often suffer
from less-than-perfect enantioselectivities, giving products that
require yield-eroding upgrading via recrystallization, or demand
reaction conditions that require specialized plant equipment for
operation, for example, high pressures and/or temperatures. In
contrast, biocatalysts offer an attractive combination of exquisite
selectivity and true sustainability, being biodegradable proteins pro-
duced from renewable resources. Directed evolution technologies
developed in the early 1990s enabled the optimization of enzymes to
function optimally in the desired process and provided a boost to the
field.2 This chapter aims to first introduce biocatalysis and directed
evolution technologies and then give specific case studies on the
development of efficient, sustainable, green-by-design biocatalytic
processes.
