This study reports methods for reductive microbial deuteration with a high degree of isotopic labelling, focusing on economical approaches using various yeast strains and inexpensive carbon sources. A strategy of α-hydrogen exchange followed by deuterative microbial reduction gave >
95% backbone perdeuteration for crucial chiral building blocks for medicinal and analytical applications, without loss of the enantioselectivity demonstrated in the corresponding protiative processes. Under an air atmosphere,