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The formal synthesis of jiadifenin, which has potent neurotrophic activity, was accomplished using intramolecular Mizoroki–Heck reaction and tandem Tsuji–Trost cyclization/lactonization reaction as key steps. Intramolecular Mizoroki–Heck reaction was employed for the construction of the A ring moiety accompanied with the formation of C9 quaternary center, which was dramatically promoted by protic solvent. Tandem Tsuji–Trost cyclization/lactonization reaction was applied to the successive cyclization of the BC ring system to elaborate under conditions, Pd(OAc) 2 , (±)-BINAP, and LiOAc in t -BuOH, leading to Theodorakis's intermediate followed by a few functionalizations. [ABSTRACT FROM AUTHOR]

For determination of the conformation of irregular sequences in glycine-rich region of the Nephila clavipes spider dragline silk, the combination of 13C selectively labeled model peptides for the typical primary structure and their 13C solid-state NMR observations is very useful (T. Asakura et al. Macromolecules. 51 (2018) 3608–3619). However, spiders produce the fiber through the stretching process in nature and therefore, it is difficult to study conformational change by stretching as mimic using the model peptides because these are generally in the powder form. In this paper, 13C selectively labeled three model peptides, (Glu) 4 (Ala) 6 Gly Gly 12 Ala 13 Gly 14 GlnGlyGlyTyrGlyGlyLeuGlySerGln Gly 25 Ala 26 Gly 27 ArgGly-GlyLeuGlyGlyGln Gly 35 Ala 36 Gly 37 (Ala) 6 (Glu) 4 with three underlined 13C labeled blocks and their poly(vinyl alcohol) blend films were prepared and the conformational changes of these peptides were monitored by stretching of the films using 13C solid-state NMR. In addition, the molecular dynamics simulation was done to evaluate change in the conformation of the sequence by stretching theoretically. The fractions of β-sheet of Ala36 and Gly37 residues in glycine-rich region adjacent to the C-terminal (Ala) 6 sequence increased significantly by stretching compared with those of other 13C labeled Ala and Gly residues. Unlabelled Image • The stretching-induced conformational changes of spider silk peptide are studied. • Determination of the fractions of conformations of peptide by solid-state NMR • Molecular dynamics simulation to evaluate conformational changes of peptide [ABSTRACT FROM AUTHOR]