68 新規カルバメート化、ラクトン化反応を経るアミノ酸類の合成

概要

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Stereoselective syntheses of 1,2- and 1,3-amino hydroxyl systems starting from acyclic unsaturated-α-amino acid derivatives via a novel t-butyldimethylsilyl carbamate or an electrophilic lactonization, and the following conversions into the biologically important amino acids, statine (1), AHPPA (2), and bulgecinine (3) are described. The newly developed method and the syntheses of unusual amino acids are characterized by the following points. (i) t-Butyldimethylsilyl carbamates, prepared from common amino protecting groups such as t-butoxycarbonyl (Boc) group and benzyloxycarbonyl (Z) group, were converted to the other N-ester groups by the treatment with F^-/RX. (ii) Cyclic carbamate formation of the t-butyldimethylsilyl carbamate 10 was initiated by F^- to give the S_N2 type reaction product 11. (iii) The S_N2' reaction of the allyl chlorides, 21a and 21b, with TBDMSOTf, AgF/Pd(II) proceeded smoothly to give the cyclic carbamates, 22a and 22b, stereoselectively, which were transformed to 1 and 2, respectively, without any racemization. (iv) Halolactonization of the Z-allyl chloride 26 provided the cis-γ-butyrolactone, predominantly, which was converted to 3. (v) Approaches to the synthesis of the right-half tripeptide of echinocandins using above mentioned strategies is also disclosed (32→31).
天然有機化合物討論会の論文
1986-09-09