Readily Available Chiral Carbon Fragments and Their Use in Synthesis

Microbiological Transformations 15. The Enantioselective Microbiological Baeyer-Villiger Oxidation of Alpha-Substituted Cyclopentanones

“…Therefore, it was of very great interest, from the chemical preparative point of view, to use these strains in order to build up a whole-cell "easy to use" procedure allowing synthesis of chiral lactones. These are interesting compounds for at least two reasons: first, chiral lactones are highly valuable synthons which can be used for synthesis of numerous natural products (Scott, 1984) and, secondly, optically active delta-lactones bearing linear five or seven carbon atom chains in the alpha-position have been described as important components of various fruit flavours (as for instance coconut, peach, mango) and are therefore of great interest to the agrochemical industry (Maga, 1976;Tress1 et al, 1978).…”

1-Arylfluorenols: Convenient preparation via the ester-mediated nucleophilic aromatic substitution protocol, facile racemization, and intrinsic chiral induction ability

“…Diastereoselective 1,2-addition of organometallics to ␣-keto acid derivatives with the aid of a chiral auxiliary provides an easy access to chiral ␣,␣-disubstituted ␣-hydroxy acid derivatives, which are important intermediates for the synthesis of biologically active natural products. 25 Therefore, a considerable number of studies have been made on the correlation between the structure of the auxiliary employed and the diastereoselectivity in the reaction, [2][3][4][5]7 which causes the reaction to be used frequently to check scope and limitation of new auxiliaries. The reaction of phenylglyoxylate 9a, derived from the racemic fluorenol 1a with methylmagnesium iodide, proceeded at room temperature to afford the addition product 10a in 96% yield with 72% de (Scheme 3).…”

1‐Arylfluorenols: Convenient preparation via the ester‐mediated nucleophilic aromatic substitution protocol, facile racemization, and intrinsic chiral induction ability

“…Diastereoselective 1,2addition of organometallics to ␣-keto acid derivatives with the aid of a chiral auxiliary provides an easy access to chiral ␣,␣-disubstituted ␣-hydroxy acid derivatives, which are important intermediates for the synthesis of biologically active natural products. 25 Therefore, a considerable number of studies have been made on the correlation between the structure of the auxiliary employed and the diastereoselectivity in the reaction, [2][3][4][5]7 which causes the reaction to be used frequently to check scope and limitation of new auxiliaries. The reaction of phenylglyoxylate 9a, derived from the racemic fluorenol 1a with methylmagnesium iodide, proceeded at room temperature to afford the addition product 10a in 96% yield with 72% de (Scheme 3).…”