Francisco Coll Manchado

Spirostanic analogues of castasterone

The synthesis, spectroscopic characterization, and biologic activity of two bioactive spirostanic analogues of the naturally occurring brassinosteroid castasterone are described.

Síntesis de espirobrasinoesteroides análogos de la 6-desoxocastasterona

The synthesis of two new spirostanic analogs of the natural occurring brassinosteroid 6-desoxocastasterone (1) is described. The scheme consists in the formation and elimination of tigogenin mesylate followed by catalytic dihydroxylation of the resulting D2-steroid (3) and acetylation of the 2a, 3a-diol introduced.Treatment diacetate (5) with NaNO2/BF3.Et2O and chromatography in alumina led to a 23-keto (6) which on reduction produced the 23S alcohol (8) as major product. Saponification of the 2a, 3a-diacetoxy-23-keto compound (6) and the 2a,3a-diacetoxy-23-hydroxy compound (8) led to the spirobrasinosteroids (7) and (9).13C NMR and 1H RMN characteristics derived from substitution at C23 are briefly discussed.

Synthesis of (22R, 25R)-3β,26-Dihydroxy-5α-furostan-6-one #

Abstract The synthesis of a plant growth promoter furostanol which bears the characteristic functionality of teasterone on rings A and B is described. # Dedicated to Dr. Charles Descoins on the occasion of his 62nd birthday.

Spirostanic analogues of teasterone. Synthesis, characterisation and biological activity of laxogenin, (23S)-hydroxylaxogenin and 23-ketolaxogenin (23-oxolaxogenin)

The synthesis and characterisation of the naturally occurring steroid sapogenin laxogenin 1 and its derivatives 23-ketolaxogenin 10 and (23S)-hydroxylaxogenin 13 are described. Compounds reported have shown plant-growth-stimulating activity in in vitro tests and in field trials.

Synthesis of (22R, 25R)-2α,3α,26-Trihydroxy-5α-furostan-6-one

Abstract The synthesis of a plant growth promoter furostanol which bears the charateristic functionality of castasterone on rings A and B is described.

Synthesis and Practical Applications of Brassinosteroid Analogs

Brassinosteroids, a new class of plant hormones of steroidal nature, show intriguing biological properties being now recognized as useful compounds in growth regulation, increasing crop yield and tolerance to abiotic stresses. Therefore, an extensive research work was planned on chemistry, biochemistry, physiology, molecular action and the synthesis of these compounds and their analogs, as the basis for further practical applications. Consequently, in Cuba, for fifteen years, the Laboratory of Natural Products from the University of Havana has been searching for new brassinosteroid analogs with biological activity that may be successfully applied to agriculture. This chapter summarizes the synthesis of several brassinosteroid analogs with structural variations in different parts of the molecules, starting from available steroids such as diosgenin, hecogenin, solasodine, solanidine and bile acids. Besides, the main results of practical applications of some formulations, which have spirostanic analogs as active ingredients, to agricultural fields and plant biotechnology are discussed.

Synthetic Steroidal Sapogenins. Part III1 23-Ketohecogenin and 23-Ketoisochiapagenin

Abstract The synthesis of the 23-keto analogues of the steroidal sapogenins hecogenin and isochiapagenin is described.

Synthesis of (25R)-5α-Spirostan-2α,3α,6β-triol Triacetate#

Abstract The synthesis of (25R)-5α-spirostan-2α,3α,6β-triol triacetate is presented. #Dedicated to Dr. Maria Dolores E. Lopez (Lita) in the occasion of her 99th birthday. †Present Address: Instituto de Productos Naturales y Agrobiologia, Apartado de Correos 195, Avda. Astrofisico F. Sanchez 3, 38206 La Laguna, Tenerife, Canary Islands, Spain.

Synthesis of Analogues of Brassinosteroids from Chenodeoxycholic Acid

The synthesis and spectroscopic characterization of two new bioactive analogues of brassinosteroids with a 24-hydroxylated cholanic side chain, an A/B ring cis-junction and oxygenated functions in C-7 is described.

Synthesis and Characterization of (25R)-2α,3α-Epoxy-5α-Spirostan-12,23-Dione

Abstract The synthesis and spectroscopic characterisation of (25R)-5oc-spirostan-12,23-dione is described