Isoxazolinium Salts in Asymmetric Synthesis. 1. Stereoselective Reduction Induced by a 3’-Alkoxy Stereocentre. A New Approach to Polyfunctionalized β-Amino Acids* [1, 2]
نویسندگان
چکیده
A new approach to optically active N-methylamino acids is presented, relying on stereoselective reduction of N-methylisoxazolinium salts with a dioxyethyl side-chain. The diastereoselectivity of the reduction step is studied systematically, in comparison with that of respective isoxazolines. A two-step transformation of isoxazolinium salts – with NaBH3(OAc) and subsequent catalytic hydrogenation as well as a one-pot reduction by catalytic hydrogenation led to high (95:5 and 87:13) diastereomeric ratios of protected erythro-N-methylaminopentanetriols. The hydroxyethyl side-chain is elaborated by oxidation to afford the β -N-methylamino acid 37, exemplifying the potential of this strategy.
منابع مشابه
2-Isoxazolinium Salts and 3-Isoxazolines: Exploratory Chemistry and Uses for the Synthesis of Branched Amino Polyols and Amino Acids*
2-Isoxazolines represent a well known class of heterocycles, readily accessible in particular by 1,3-dipolar cycloaddition of nitrile oxides to alkenes. 2-Isoxazolines are easily transformed into 2isoxazolinium salts by N-methylation, and further into 3-isoxazolines by deprotonation. In contrast to the parent system, less is known concerning the chemistry of the derived classes, and potential a...
متن کاملA Crystallization-Induced Asymmetric Transformation using Racemic Phenyl Alanine Methyl Ester Derivatives as Versatile Precursors to Prepare Amino Acids
L-Tyrosine and L-Dopa are the precursors in the biological synthesis of amine neurotransmitters. On the other hand, phenylalanine as an aromatic amino acid (AAA) is a precursor in the synthesis of L-Tyrosine and L-Dopa. For some substrates such as amino acids, resolution by the formation of diastereomers offers an attractive alternative. Among different methods in this case, crystallization-ind...
متن کاملNew Approaches to Branched β-Amino α-Hydroxy Acids, Taxol Side-chain Analogs
The stereoselective synthesis of β -amino acids and their derivatives has been an active area of research, due to the importance of β -amino acids in various fields [1]. In particular, non-proteinogenic β -amino α-hydroxy acids are found in many natural products and drugs, for example N-benzoyl-3-phenylisoserine as a side-chain of taxol which has been approved for treatment of ovarian and breas...
متن کاملStereoselective Synthesis of α-Arylalkylamines by Glycosylation-induced Asymmetric Addition of Organometallic Compounds to Imines
Arylalkylamines are of interest as building blocks for the synthesis of biologically active compounds and as chiral ligands or chiral auxiliaries in stereoselective syntheses [1]. Their stereoselective synthesis has been achieved by enantioselective reduction of ketimines using chiral reagents [2], as for example Corey’s oxaborolidines [3], or proline-derived triacyloxyborohydrides [4]. Particu...
متن کاملAsymmetric synthesis and teratogenic activity of (R)- and (S)-2-ethylhexanoic acid, a metabolite of the plasticizer di-(2-ethylhexyl)phthalate.
The stereoselectivity of the teratogenic activity of 2-ethylhexanoic acid (EHXA), a metabolite of the widely-used plasticizer di-(2-ethylhexyl)phthalate, was investigated. The enantiomers of EHXA were prepared via asymmetric synthesis with the aid of the chiral auxiliaries (R)- and (S)-1-amino-2-(methoxymethyl)pyrrolidine (RAMP, SAMP). The aqueous solutions of the sodium salts of (R)- and (S)-E...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2004