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Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate.

ABSTRACT: Esters of crotonic acid were brominated on a multigramme scale using a free radical procedure. A phase transfer catalysed fluorination transformed these species to the 4-fluorobut-2E-enoates reproducibly and at scale (48-53%, ca. 300 mmol). Asymmetric dihydroxylation reactions were then used to transform the butenoate, ultimately into all four diastereoisomers of a versatile fluorinated C4 building block at high enantiomeric-enrichment. The (DHQ)2AQN and (DHQD)2AQN ligands described by Sharpless were the most effective. The development and optimisation of a new and facile method for the determination of ee is also described; (19)F{(1)H} spectra recorded in d-chloroform/diisopropyl tartrate showed distinct baseline separated signals for different enantiomers.

SUBMITTER: Laurenson JA

PROVIDER: S-EPMC3869297 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate.

Laurenson James A B JA Parkinson John A JA Percy Jonathan M JM Rinaudo Giuseppe G Roig Ricard R

Beilstein journal of organic chemistry 20131126

Esters of crotonic acid were brominated on a multigramme scale using a free radical procedure. A phase transfer catalysed fluorination transformed these species to the 4-fluorobut-2E-enoates reproducibly and at scale (48-53%, ca. 300 mmol). Asymmetric dihydroxylation reactions were then used to transform the butenoate, ultimately into all four diastereoisomers of a versatile fluorinated C4 building block at high enantiomeric-enrichment. The (DHQ)2AQN and (DHQD)2AQN ligands described by Sharpless ...[more]

PMID: 24367430

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