One-Step Synthesis of Triphenylphosphonium Salts from (Het)arylmethyl Alcohols

Two approaches for the synthesis of substituted phosphonium salts from easily available benzyl alcohols and their heterocyclic analogs have been developed. The developed protocols are complementary: the direct mixing of alcohol, trimethylsilyl bromide, and triphenylphosphine in 1,4-dioxane followed by heating at 80 °C was found to be more efficient for acid-sensitive substrates, such as salicyl or furfuryl alcohols as well as secondary benzyl alcohols, while a one-pot procedure including sequential addition of trimethylsilyl bromide and triphenylphosphine gave higher yields for benzyl alcohols bearing electroneutral or electron-withdrawing substituents.

Total Synthesis of Oxepin and Dihydrooxepin Containing Natural Products

The construction of oxepin and dihydrooxepin containing natural products represents a challenging task in total synthesis. In the last decades, a variety of synthetic methods have been reported for the installation of these structural motifs. Herein, we provide an overview of synthetic methods and strategies to construct these motifs in the context of natural product synthesis and highlight the key steps of each example.

Molecular Pharmacology of Rosmarinic and Salvianolic Acids: Potential Seeds for Alzheimer's and Vascular Dementia Drugs

Both caffeic acid and 3,4-dihydroxyphenyllactic acid (danshensu) are synthesized through two distinct routs of the shikimic acid biosynthesis pathway. In many plants, especially the rosemary and sage family of Lamiaceae, these two compounds are joined through an ester linkage to form rosmarinic acid (RA). A further structural diversity of RA derivatives in some plants such as Salvia miltiorrhiza Bunge is a form of RA dimer, salvianolic acid-B (SA-B), that further give rise to diverse salvianolic acid derivatives. This review provides a comprehensive perspective on the chemistry and pharmacology of these compounds related to their potential therapeutic applications to dementia. The two common causes of dementia, Alzheimer's disease (AD) and stroke, are employed to scrutinize the effects of these compounds in vitro and in animal models of dementia. Key pharmacological mechanisms beyond the common antioxidant and anti-inflammatory effects of polyphenols are highlighted with emphasis given to amyloid beta (Aβ) pathologies among others and neuronal regeneration from stem cells.