Synthesis of (22R,23R)-22,23-epoxy-3β,5α-dihydroxystigmastan-6-one from Stigmasterol

Abstract

A new (22R,23R)-22,23-epoxy-3β,5α-dihydroxy-stigmastan-6-one brassinosteroid analogue has been synthesised from stigmasterol 1 and its activity as a plant growth promoter has been tested.

Synthesis and Biological Activity of Epoxy Analogues of 3-dehydroteasterone

“…The NMR spectral assignments for the steroids were based on previously reported data from similar steroids. 12,20 The integral of the H 22 and H 23 signals in the 1 H NMR spectra 12 were used to asses the proportions of diastereomeric 22,23-epoxides in the mixtures 5A/5B and 6A/6B.…”

“…The 22R,23R epoxy steroids 5A and 6A differ from 22S,23S epoxy compounds 5B and 6B by the chemical shifts of C17, C22 and C23, and the values correspond with the previous report. 12,[20][21][22] In the R,R-epoxy, the C22 and C23 show a very similar chemical shift (∆δ ≈ 0.1-0.2 ppm); whereas in the S,Sepoxy those carbons are clearly distinguishable (∆δ ≈ 4.3-4.6 ppm) . 21 In the radish (Raphanus sativus) cotyledon expansion test 23 , which is used to detect citokynine-like activity, solutions of the mixture of 6A and 6B showed plant growth promoting activity in all concentrations (10 -4 -10 -7 mg/ml).…”

“…However, many BS analogues with 22,23 epoxy ring or 5a-hydroxy-6-ketone functions have been synthesised and tested as plant growth regulators. [11][12][13][14][15][16][17][18][19][20] Here we describe in two different syntheses of two new analogues of 3-dehydroteasterone, the (22R,23R)-22,23-epoxy-5a-hydroxystigmastan-3,6-dione 6A and the (22S,23S)-22,23-epoxy-5a-hydroxystigmastan-3,6-dione 6B. Both steroids possess a 3,6-dione with the 5a-hydroxyl group and an epoxide in the side chain.…”

Synthesis of New Steroidal Carbamates with Plant-Growth-Promoting Activity: Theoretical and Experimental Evidence

“…Following a procedure previously described [ 59 , 60 ], the mixture 12a / 12b was cooled in an ice bath. After 5 min, HClO 4 (3.9 mL, 65.1 mmol) was added dropwise.…”

“…The crystal structure of the protein Brassinosteroid Insensitive 1 (BRI1) in complex with BRI1-Associated Receptor Kinase 1 (BAK1) and the natural ligand 1 , PDB ID: 4m7e, resolved at 3.60 Å was retrieved from Protein Data Bank ( ; accessed on 2–15 January 2019). The structure was optimized using pdb2pqr.py (Version 2.0.0) implemented in the web server PDB2PQR ( ; accessed on 3–22 February 2019), using the AMBER force-field, and the protonation state of ionizable groups at pH 8 was assigned using PROPKA [ 58 , 59 ]. The grid search was selected of size 22 × 22 × 22 Å [ 62 ] with the center of simulation box matching the center of 1.…”