¹H and ¹³C NMR analysis of brassinosteroids

Abstract

The 'H and I3C NMR spectra of the two phytohormones, brassinolide and 24-epi-brassinolide, and the two synthetic analogues 22,23,24trisepi-brassinolide and (22S,23S)-2&homo-brassinolide, were assigned using 1 D aod 2D NMR techniques. Independent assignment strategies are presented for the 'H and "C chemical shifts of the steroidal side-chain.

Anti-herpetic and anti-inflammatory activities of two new synthetic 22,23-dihydroxylated stigmastane derivatives

“…Configurations at C-22 and C-23 in the new compounds were established by comparison with NMR chemical shifts and coupling constants of known closely related structures [14].…”

Side Chain Conformation of the Growth-Promoting Phytohormones Brassinolide and 24-Epibrassinolide

“…We used a combination of 2D techniques (COSY DQF, HMQC, HMBC) as described in the previous paper. 20 The distinction of the diastereotopic protons (a and b) of the steroidal skeleton can easily be done by NOE di †erence spectroscopy with saturation of the two b-angular methyl groups Me-18 and Me-19 which give NOEs to all desired b protons. The 1H and 13C chemical shift values are given in Table 1.…”

Synthesis of tritium labelled 24‐epibrassinolide

“…The exchange rate was determined on the basis of the mass spectroscopic data given in Table 1. The position of the introduced deuterium followed from the NMR spectrum of 2 which lacked the signals for the 5a-and 7a,7B-protons at 2,57 and 2,33 ppm, respectively [8]. Baeyer-Villiger oxidation of 2, using CF3C03H in CHzC12 gave the 7-oxa-6-0x0-lactone 4 besides approximately 10% of the undesired epimeric 6-oxa-7-0x0-lactone, separated by S O 2 chromatography.…”