Stereoselective total synthesis of arachnid harvestmen natural product: (4S,5S)‑4-hydroxy-γ-decalactone

Herein, we described the novel synthetic strategy for the total synthesis of harvestmen natural product (4S,5S)‑4-hydroxy-γ-decalactone (minor) from an inexpensive precursor ((R)-2,2-dimethyl-1,3-dioxolane-4-carbaldehyde) with 31% overall yield. Hydroxy-γ-lactones represent a special class of harvestmen exocrine defense compounds. The present convergent synthesis utilizes classical reactions like the Barbier reaction, the Grignard reaction, and the employment of an olefin as a masked carboxylic acid functionality followed by lactone formation as key steps.

Zinc Chloride-Catalyzed Synthesis of Carbamates: An Application for the Synthesis of the Anti-Alzheimer's Drug Rivastigmine

Herein, we report a synthetic protocol for the synthesis of carbamates by employing zinc chloride as a catalyst from carbamoyl chlorides and aromatic/aliphatic alcohols. The developed protocol successfully utilizes the gram-scale synthesis of the FDA-approved rivastigmine drug and its derivative. The utility of zinc chloride over other catalysts such as zinc dust and zinc acetate exhibits a 49-87% yield of carbamates.

Enhanced production of violacein by Chromobacterium violaceum using agro-industrial waste soybean meal

AIMS

The research is aimed at developing an economic and sustainable growth medium using abundantly available and highly nutritive agro-industrial waste soybean meal as the substrate for the production of violacein by Chromobacterium violaceum.

METHODS AND RESULTS

Violacein produced using soybean meal medium was compared with the commercial complex growth media. Upon utilization of 2% w/v soybean meal (SM2 ) medium, 496 mg/L crude violacein was achieved after 48-hr incubation time, which was 1.62-fold higher than the crude violacein produced in Luria-Bertani (LB) broth. Additionally, supplementation of 100 mg/L L-tryptophan to 1% and 2% w/v soybean meal (SMT1 and SMT2 ) medium yielded 1217 mg/L (3.96-fold higher as compared to LB) and 1198 mg/L (3.90-fold higher as compared to LB) crude violacein respectively. Optimization of culture conditions and concentration of L-tryptophan using Box-Behnken design (BBD) model produced as high as 1504.5 mg/L crude violacein. To the best of our knowledge, this is the highest crude violacein produced to date using agro-industrial-based waste as a substrate with minimal supplementation in a shake flask.

CONCLUSIONS

The study signifies the potentiality of soybean meal as a cost-effective growth medium for the production of violacein. Optimization of the fermentation parameters clearly demonstrated a surge in violacein production.

SIGNIFICANCE AND IMPACT OF THE STUDY

Utilization of soybean meal as an alternative to the expensive commercial media would surely promote the large-scale synthesis of this multifaceted compound.

Synthetic Approaches toward the Synthesis of Brivaracetam: An Antiepileptic Drug

Epilepsy is a chronic neurological disorder in the brain, affecting individuals of all age groups. Nearly 1% of the world population is affected by seizure disorder, of which 80% of the patients are observed in underdeveloped and developing countries. The predominant treatment option for epilepsy includes an antiepileptic drug named brivaracetam. This drug emerged as an unusual success of rational drug discovery in clinical development by exhibiting magnificent affinity toward synaptic vesicle glycoprotein as compared to conventional drug levetiracetam and piracetam. Given its efficiency in limiting the progression of epilepsy, this drug has drawn considerable attention of researchers to devise novel routes of its synthesis. The present review encapsulates the reported literature on synthetic strategies for brivaracetam, which will assist medicinal chemists in the further progress of its synthesis.