Progress in Heterocyclic Chemistry (PHC) is an annual review series commissioned by the International Society of Heterocyclic Chemistry (ISHC). Volumes in the series contain both highlights of the previous year's literature on heterocyclic chemistry and articles on emerging topics of particular interest to heterocyclic chemists. The chapters in Volume 21 constitute a systematic survey of the important original material reported in the literature of heterocyclic chemistry in 2008. Additional articles in this volume review "Biocatalytic approaches to chiral heterocycles" and "Ring-expanded ('fat') purines and their nucleoside/nucleotide analogues as broad-spectrum therapeutics." As with previous volumes in the series, Volume 21 apprises academic/industrial chemists and advanced students of developments in heterocyclic chemistry in a convenient format. * Covers the heterocyclic literature published in 2008 * Includes specialized reviews * Features contributions from leading researchers in their fields