ABSTRACT
Asymmetric hydrogenations are increasingly being used to introduce stereogenic centres into products used in the life sciences industries. There are a number of potential pitfalls when moving from a laboratory reaction to a manufacturing process, not least of which is safety. Time-to-market pressure leads to short development times, which in the past could be a large barrier for the implementation of catalytic steps; now there are new ways to minimise this problem. The potential problems associated with impurities and other methods that can shut down the hydrogenation reactions are highlighted in this critical review (353 references).
Subject(s)
Hydrogenation , Catalysis , Drug Evaluation, Preclinical , Humans , Industry , Organic Chemicals/chemistry , SafetyABSTRACT
New methods to unnatural amino acids continue to be developed. This review covers methods, published in 2001, that employ an asymmetric hydrogenation, a transition metal-catalyzed reaction, an enzymatic resolution or a chiral auxiliary.
Subject(s)
Amino Acids/chemical synthesis , Amino Acids/metabolism , Technology, Pharmaceutical/methods , Animals , Humans , Hydrogenation/drug effects , StereoisomerismABSTRACT
Noteworthy developments of the Peterson olefination reaction are reviewed. Evidence for both concerted and stepwise mechanisms for the Peterson olefination reaction is presented. The strong affinity of the oxygen anion for the silyl moiety is emphasised when the Peterson olefination reaction takes preference over both the Julia and Wittig reactions in the presence of S- and P-stabilised silyl carbanions. Cerium-mediated Peterson methylenation reactions are discussed.
