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A series of PN(sp2)P ligands containing two stereogenic carbon centers were generated via the palladium(II) catalyzed asymmetric hydrophosphination of 2,6-pyridyl dienones using diphenylphosphine. Although the targeted tridentate products are powerful metal ion sequesters, poisoning of the metal catalyst due to irreversible chelation by the adducts during the course of the addition reaction was circumvented via this protocol. The reported procedure thus enabled the efficient access toward chiral PN(sp2)P pincer-type ligands in a one-pot, single-step process with good conversions and high enantioselectivities. The formed ligands can be further coordinated to various metal centers to form chiral PNP complexes with potential synthetic applications. Ministry of Education (MOE) We wish to acknowledge the research funding provided by the Singapore Ministry of Education Academic Research Fund Tier I (Grant ID 2019-T1-001-094) to support this work.

Lagerstroemia indica is an important ornamental tree worldwide. The development of cultivars with colorful leaves and increased ornamental value represents one of the current main research topics. We investigated the anthocyanin profiles in two contrasting cultivars for leaf color phenotypes and explored the underlying molecular basis. Both cultivars display purple-red young leaves (Stage 1), and when the leaves mature (Stage 2), they turn green in HD (Lagerstroemia Dynamite) but remain unchanged in ZD (Lagerstroemia Ebony Embers). Seven different anthocyanins were detected, and globally, the leaves of ZD contained higher levels of anthocyanins than those of HD at the two stages with the most pronounced difference observed at Stage 2. Transcriptome sequencing revealed that in contrast to HD, ZD tends to keep a higher activity level of key genes involved in the flavonoid&ndash, anthocyanin biosynthesis pathways throughout the leaf developmental stages in order to maintain the synthesis, accumulation, and modification of anthocyanins. By applying gene co-expression analysis, we detected 19 key MYB regulators were co-expressed with the flavonoid&ndash, anthocyanin biosynthetic genes and were found strongly down-regulated in HD. This study lays the foundation for the artificial manipulation of the anthocyanin biosynthesis in order to create new L. indica cultivars with colorful leaves and increased ornamental value.

A ruthenacycle-catalyzed one-pot β-alkylation of secondary alcohols with primary alcohols is described. A survey of four C–N chelate ruthenacycles synthesized via the cyclometallation reaction of phenylmethanamine, N-methylphenylmethanamine, N,N-dimethylphenylmethanamine, and naphthalen-1-ylmethanamine with [(η6-C6H6)RuCl2]2 was undertaken. All four complexes were found to be active with the phenylmethanamine-based ruthenacycle showing the best combination of reactivity and product selectivity among the four. An expanded scope of substrates was also studied with the inclusion of unsaturated primary alcohols. The reactivity trend observed gave insights into the role of hydrogen bonding in the catalytic mechanism involving transfer hydrogenation between the substrates and the transition metal catalyst.