The remarkable effect of the 7-substituent in the diastereoselective oxidative rearrangement of indoles: Asymmetric synthesis of 3,3-disubstituted oxindoles

International audienceThe nature of the 7-substituent has a remarkable effect on the diastereoselectivity of the oxidative rearrangement of indole-2- carboxamides derived from (S)-2-methoxymethylpyrrolidine into chiral 3,3-disubstituted oxindoles

Oxidative rearrangement of indoles: a new approach to the EFHG-tetracyclic core of diazonamide A.

International audienceA new approach to the ring EFHG-tetracyclic core fragment of the marine secondary metabolite diazonamide A is described. The route is based on the oxidative rearrangement of 3-arylindole-2-carboxylates. Thus, a range of 3-arylindole-2-carboxylates (3, 8) underwent rearrangement to the corresponding 3,3-disubstituted oxindoles (4, 9) with migration of the ester group upon treatment with tert-butyl hypochlorite followed by acid. The oxindoles 9 with a 3-[2-(4-methoxybenzyloxy)]phenyl substituent underwent cyclization to the tetracyclic aminals 11 following N-protection, reduction, and treatment with methanesulfonic anhydride. The methodology was applied to the tyrosine-indole derivative 17 to give the EFHG-tetracyclic core of diazonamide A

Design, Synthesis and Biological Evaluation of Strigolactone and Strigolactam Derivatives for Potential Crop Enhancement Applications in Modern Agriculture

Strigolactones have been known as signaling molecules in the rhizosphere of plants since more than 50 years. However, their roles as phytohormone have been only recognized since 2008. We describe here a very efficient synthetic access to representative canonical strigolactones displaying the A-B-C-D tetracyclic structure and to non-canonical strigolactones as carlactonoic acid and methyl carlactonoate. In addition, we report the design and the synthesis of strigolactams as promising derivatives of strigolactones for potential use in modern agriculture. Among the synthetic methods developed for this project, the intramolecular [2+2] cycloaddition of keteneiminium salts to C=C bond has been particularly useful to the synthesis of natural strigolactones and their potentially improved analogues

Chemicals Inducing Seed Germination and Early Seedling Development

Seed germination and early seedling development are essential events in the plant life cycle that are controlled largely by the interplay and cross-talk between several plant hormones. Recently, major progress has been achieved in the elucidation at the molecular level of the signalling of these phytohormones. In this review, we summarise the data for the most promising classes of compounds, which could find potential agronomic applications for promoting seed germination and early seedling development even under abiotic stress conditions. Structural modifications of plant hormones are required to improve their biological performance and their specificity to allow commercial application