Cyclohexyl-based chiral auxiliaries

Applications of liver acetone powders in enantioselective synthesis

“…24,45 It occurred to us that if we have sterically more demanding aromatic groups in the cyclohexane ring, the resulting trans-2-arylcyclohexan-1-ols might offer better enantioselectivities in chiral auxiliary mediated asymmetric reactions. Accordingly, we planned to prepare various trans-2-arylcyclo-hexan-1-ols in enantiomerically pure form via the hydrolysis of the corresponding racemic acetates with PLAP.…”

“…24 With a view that chiral trans-2-aryloxycyclohexan-1-ols will offer promise as useful chiral auxiliaries, we have successfully used pig liver acetone powder (PLAP) as chiral source for enantioselective hydrolysis of racemic trans-1-acetoxy-2-aryloxycyclohexanes to provide the resulting (-)-(R,R)-2-aryloxycyclohexan-1-ols in very high enantiomeric purities [25][26] (13->99%) and in 24-47% isolated yields 27 (Scheme 1). The (R,R)-selectivity in the hydrolysis of racemic trans-1-acetoxy-2-aryloxy-cyclohexanes can be possibly explained on the basis of the Jones three dimensional active site model.…”

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).…”

“…Among such entities, cyclohexanol-based chiral auxiliaries, [1][2][3][4][5] especially those bearing an aryl substituent such as Corey's 8-phenylmenthol 6 and Whitesell's trans-2-phenylcyclohexanol 7 fulfilled big roles because of their high stereoselectivity and wide applicability.…”

Hoch diastereoselektive eisenvermittelte C(sp2)‐C(sp3)‐Kreuzkupplungen zwischen Aryl‐Grignard‐Reagentien und cyclischen Iodhydrinderivaten

“…Produkte des Typs 1 stellen vielseitige Bausteine für Pharmazeutika, [10] chirale Liganden [11] und Auxiliare dar. [12] Sie werden gewöhnlich durch Öffnung der entsprechenden Epoxide mit Arylmetallverbindungen erhalten. Enantioselektive Varianten dieser Ringöffnung sind selten.…”