Dataset Information

Single enantiomer epoxides by bromomandelation of prochiral alkenes.

ABSTRACT: A combination of mandelic acid and N-bromosuccinimide efficiently converts prochiral alkenes into a readily separable 1:1 mixture of the bromomandelates. The diastereomerically pure bromomandelates are then converted into a variety of enantiomerically pure products. Terminal alkenes are converted into enantiomerically pure epoxides. Cyclohexene is converted into enantiomerically pure cis-2-azidocyclohexanol and cis-2-phenylthiocyclohexanol.

SUBMITTER: Taber DF

PROVIDER: S-EPMC3248826 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

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Publications

Single enantiomer epoxides by bromomandelation of prochiral alkenes.

Taber Douglass F DF Liang Jiang-lin JL

The Journal of organic chemistry 20070101 2

A combination of mandelic acid and N-bromosuccinimide efficiently converts prochiral alkenes into a readily separable 1:1 mixture of the bromomandelates. The diastereomerically pure bromomandelates are then converted into a variety of enantiomerically pure products. Terminal alkenes are converted into enantiomerically pure epoxides. Cyclohexene is converted into enantiomerically pure cis-2-azidocyclohexanol and cis-2-phenylthiocyclohexanol. ...[more]

PMID: 17221958

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Project description:ImportanceChiral switching, a strategy in which drug manufacturers develop a single-enantiomer formulation of a drug to be substituted for a racemic formulation, allows manufacturers to maintain market exclusivity for drugs losing patent protection, even without demonstrating superior efficacy or safety.ObjectiveTo identify and characterize all randomized clinical trials (RCTs) directly comparing a Food and Drug Administration (FDA)-approved single-enantiomer drug against a previously approved racemic drug for 1 or more efficacy or safety end points.Evidence reviewDrugs were identified using the Drugs@FDA database. Randomized clinical trials were identified using Ovid MEDLINE (1949 to October 22, 2019), Ovid Embase (1974 to October 22, 2019), Web of Science Core Collection (all years), ClinicalTrials.gov, and Cochrane Central Registry of Controlled Trials (CENTRAL, Wiley, Issue 8 of 12, October 22, 2019). Trials were characterized as favoring the single-enantiomer or racemic drugs based on whether the primary efficacy, secondary efficacy, and safety end points achieved each study's defined significance level (eg, P < .05). Trials were characterized as favoring neither drug if no statistically significant differences were reported for any end point or if both drugs were found to be superior for 1 or more separate end points.FindingsFifteen FDA-approved single-enantiomer drugs were identified with racemic precursors approved in the US or Europe. For 3 single-enantiomer racemic drug pairs, no RCTs directly comparing the drugs were identified. For the remaining 12 pairs, 185 RCTs comparing efficacy or safety of the drug pairs were identified, 124 (67.0%) of which studied 1 pair (levobupivacaine/bupivacaine). There were 179 RCTs directly comparing drug pairs using efficacy end points, of which 23 (12.8%) favored the single enantiomer based on primary efficacy end point results. There were 124 RCTs directly comparing drug pairs using safety end points, of which 17 (13.7%) favored the single-enantiomer drug. For 9 of the 15 single-enantiomer drugs (60.0%), no RCTs were identified providing evidence of improved efficacy, based on primary end point results, or safety as compared with their racemic precursors.Conclusions and relevanceThe results of this systematic review suggest that most newly marketed FDA-approved single-enantiomer drugs are infrequently directly compared with their racemic precursors, and when compared, they are uncommonly found to provide improved efficacy or safety, despite their greater costs.

Dataset Information

Single enantiomer epoxides by bromomandelation of prochiral alkenes.

Publications

Single enantiomer epoxides by bromomandelation of prochiral alkenes.

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