137820-95-2Relevant academic research and scientific papers
Asymmetric synthesis of benzilic acid analogues using 8-phenylmenthol as a chiral auxiliary
Kiesewetter
, p. 2183 - 2198 (2007/10/02)
Our program on the synthesis of 18F-labeled muscarinic receptor ligands required the preparation of chiral fluoroalkyl benzilic acids. An enantioselective synthesis of substituted benzilic acids was achieved using 8-phenylmenthol as the chiral auxiliary. Grignard addition to the si face of 8-phenylmenthyl benzoylformate 7 proceeded with high selectivity. The results of the chiral induction support assignments of the chirality of benzilic acids previously resolved by crystallization. The method was used to synthesize (R)-quinuclidinyl-(R)-4-iodo)benzilate, which proved identical to an authentic sample. In addition, the method allows the preparation of (R)- and (S)-fluoroethyl benzilic acids in a stereoselective manner.
Synthesis of the Four Stereoisomers of 1-Azabicyclooct-3-yl-α-hydroxy-α-(4-phenylboronic acid)-α-phenylacetae (QNB-Boronic acid), including a preparative HPLC method to separate diastereoisomeric mixtures with high optical purity
Nanjappan, P.,Ramalingam, K.,Nowotnik, D. P.
, p. 1271 - 1282 (2007/10/02)
The four stereoisomers of 1-azabicyclooct-3-yl-α-hydroxy-α-(4-phenylboronic acid)-α-phenylacetate (QNB boronic acids, 1a-1d) were synthesized initially via 1-azabicyclooct-3-yl-α-hydroxy-α-(4-iodophenyl)-α-phenylacetate (iodo-QNBs, 6a-6d) using an adaptation of a published procedure.The number of steps involved were reducted substantially using a distinctly different approach.This involved the synthesis of diastereoisomers of QNB-boronic acid, followed by separation and isolation of enantiomers by preparative reversed-phase HPLC.An improved method of synthesis of α-hydroxy-α-(4-aminophenyl)-α-phenyl-acetic acid (3a and 3b) from α-hydroxy-α-(4-nitrophenyl)-α-phenylacetic acid (2a and 2b) is also described.
