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Journals and Conferences
The xylem conducts water and minerals from the root to the shoot and provides mechanical strength to the plant body. The vascular precursor cells of the procambium differentiate to form continuous vascular strands, from which xylem and phloem cells are generated in the proper spatiotemporal pattern. Procambium formation and xylem differentiation are… (More)
A total synthesis of brevenal is described. The pentacyclic ether core was constructed by the intramolecular allylation of alpha-acetoxy ether and subsequent ring-closing metathesis. Both of the diene side chains were introduced by Wittig olefination and a Horner-Wadsworth-Emmons reaction, respectively, in a highly stereoselective manner.
The convergent total syntheses of gambierol (1) and 16-epi-gambierol (2) have been achieved. The ABC and FGH ring segments 4 and 5 were prepared from known compounds 6 and 13, respectively, by linear manners. The fragments prepared were connected by our own synthetic strategy including the intramolecular allylation of alpha-acetoxy ether followed by… (More)
The convergent total synthesis of gambierol (1) is described. The octacyclic ether framework of 1 was constructed via the intramolecular allylation of alpha-chloroacetoxy ether followed by ring-closing metathesis. A modified Stille coupling was successfully applied to the synthesis of the triene side chain.
Strategies for the synthesis of polycyclic ethers based on intramolecular allylations are overviewed. The intramolecular condensation of allylic stannanes and aldehydes is a powerful tool for the synthesis of oxepane derivatives. The reaction is successfully applied to the iterative total synthesis of hemibrevetoxin B (2). Further, the intramolecular… (More)
The convergent total synthesis of brevetoxin B (1) has been achieved. The intramolecular allylation of the O,S-acetal 20, prepared from the alpha-chlorosulfide 17 and the alcohol 5, was carried out using AgOTf as a Lewis acid to give the diene 21, predominantly. Ring-closing metathesis of 21 with the Grubbs catalyst 23 afforded the hexacyclic ether 25 which… (More)
The allylation of aromatic amines with alkynes proceeded smoothly in the presence of catalytic amounts of Pd(PPh(3))(4) and benzoic acid. The allylation products were obtained in high yields in a regio- and stereoselective manner. The effect of various groups on the nitrogen atom of anilines was studied. Regardless of the substituent (electron withdrawing… (More)
A highly stereoselective and stereodivergent synthesis of two possible diastereomers of (-)-gummiferol was achieved, wherein the stepwise epoxidation and Cadiot-Chodkiewicz reaction were utilized for the construction of the diepoxide moiety and triacetylene part, respectively. Detailed comparison of their (1)H and (13)C NMR data and specific rotation with… (More)
The Lewis acid mediated reaction of alpha-acetoxy ethers 15-22 gave the corresponding cyclized products 23, 25, 27, 29, 31, 32, 34, and 36 in good yields with high stereoselectivities. Those cyclized products were subjected to ring-closing metathesis to afford the polycyclic ethers 38-42, 44, and 45 in good yields. The usefulness of the present methodology… (More)
The first total syntheses of sarcophytonolide H and the originally proposed and correct structures of isosarcophytonolide D have been achieved via transannular ring-closing metathesis (RCM). These total syntheses culminated in the stereostructural confirmation of sarcophytonolide H and the reassignment of isosarcophytonolide D, respectively. The antifouling… (More)