Many natural products contain unusual aromatic β-amino acids or moieties derived therefrom. The biosynthesis of these β-amino acids was first elucidated during a biosynthetic study of the enediyne antitumor antibiotic C-1027, when an enzyme, SgcC4, was discovered to convert L-tyrosine to (S)-β-tyrosine. SgcC4 is similar in sequence and structure to 4-methylideneimidazole-5-one (MIO)-containing ...

Excess production of nitric oxide by activated macrophages via inducible nitric oxide synthase leads to the development of various inflammatory diseases. Heme oxygenase-1 expression via activation of nuclear factor-erythroid 2-related factor 2 inhibits nitric oxide production and inducible nitric oxide synthase expression in activated macrophages. Okanin is one of the most abundant chalcones fo...

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or...

α,β-Unsaturated esters are versatile building blocks for organic synthesis and of significant importance for industrial applications. A great variety of synthetic methods have been developed, and quite a number of them use aldehydes as precursors. Herein we report a chemo-enzymatic chain elongation approach to access α,β-unsaturated esters by combining an enzymatic carboxylic acid reduction and...

Herein, we describe the concise synthesis of 2,6-cis-substituted tetrahydropyran derivatives based on a domino olefin cross-metathesis/intramolecular oxa-conjugate cyclization (CM/IOCC) reaction. We have found that the domino CM/IOCC of δ-hydroxy olefins with α,β-unsaturated carbonyl compounds (e.g., trans-crotonaldehyde or N-acryloyl-2,5-dimethylpyrrole) could be efficiently achieved in the pr...

Abstract: A reusable PdCl2(NH3)2/cationic 2,2′-bipyridyl system was used to catalyze the double Mizoroki-Heck reaction of aryl iodides with electron-deficient alkenes in water in the absence of inert gas, giving β,β-diarylated carbonyl derivatives in good to excellent yields. The formation of unsymmetrical β,β-diarylated alkenes were also studied by coupling aryl iodides with the corresponding ...

The β-borylation reaction of α,β-unsaturated aldehyde-derived imines, formed in situ, has been studied using a one-pot methodology, as a route to β-boryl aldehydes. The instability of the β-boryl aldehydes meant that derivatisation was required and routes to both acetal derivatives and homoallylic boronates were examined. β-Boryl acetals were also found to be unstable, however, the formation of...

The 5-endo-trig-type cyclization has been performed using a Pd-bis(isoxazoline) catalyst. The present cyclization of β,γ-unsaturated carbonyl compounds gave γ-butenolides and 3-pyrrolin-2-ones in good to excellent yields.

A method to oxidatively cleave allyl ethers to their corresponding aldehydes mediated by an oxoammonium salt is described. Using a biphasic solvent system and mild heating, cleavage proceeds readily, furnishing a variety of α,β-unsaturated aldehydes and ketones.