Thermal Cyclization of Copper Carbenoid of α‐Dizao α‐Phosphorylacetate: Unexpected and Novel Access to Oxaphosphirane

Under the catalysis of Cu(OTf)₂ in refluxing CH₂Cl₂, ethyl α‐dizao α‐(diethylphosphoryl)acetate was shown to undergo a new cyclization reaction to afford a pentacovalent oxaphosphirane product. The reaction is proposed to occur through the addition of the P=O double bond to the copper carbenoid, followed by the hydrolysis of the ylide intermediate. Our finding represents the first example on producing oxaphosphiranes from dizao phosphoryl compounds. On the other hand, the corresponding rhodium carbenoid displayed the different reactivity under the same thermal conditions, to produce the β‐propiolactone through the well‐recognized C‐H insertion pathway.     

Two New Triterpene Saponins from the Seed Residue of Hippophae rhamnoides L.

Two new triterpene saponins, named hippophosides E and F ( 1 and 2 , resp.), together with two known compounds, were isolated from the seed residue of Hippophae rhamnoides L. Their structures were elucidated on the basis of chemical and spectral analysis, including 1D‐ and 2D‐NMR and HR‐MS experiments, and by comparison with literature data.     

Structure and Absolute Configuration of Aspergilumamide A,a Novel Lumazine Peptide from the Mangrove‐Derived Fungus Aspergillus sp.

A novel lumazine peptide, aspergilumamide A ( 1 ), as well as a known analog penilumamide ( 2 ), were isolated from the mycelia of a marine‐derived fungus Aspergillus sp. (33241), obtained from the mangrove Bruguiera sexangula var. rhynchopetala collected from the South China Sea. The structure of 1 was identified by comprehensive spectroscopic analysis, including 1D‐ and 2D‐NMR, ESI‐MS, and MS/MS experiments. The absolute configuration of 1 was determined by Marfey's method.     

Biocatalytic Synthesis of the Anti‐diabetes Agent‐corosolic Acid by Whole Cells of Microorganisms

Diabetes is one of the most prevalent and costly global diseases. For diabetes, frequent insulin treatment and synthetic drugs are very expensive and may cause unwanted side effects. Corosolic acid (CA), a natural product, was reported to be efficient in the treatment of diabetes, meanwhile without induction of anti‐insulin antibodies and obesity. The preparation of CA attracted many researchers in the world. This study investigated the biocatalytic synthesis method of CA from ursolic acid by Streptomyces griseus subsp. griseus 4.18. LC? MS analysis demonstrated that 5 day, 125 μg/mL substrate, pH=9 and 10% strain concentration were the appropriate conditions. It is estimated that biocatalysis will contribute to the development of green and sustainable synthetic processes with less time‐consuming and more environmentally friendly.     

Design,Synthesis, and Herbicidal Evaluation of Novel Uracil Derivatives Containing 1,3,4‐Thiadiazolyl Moiety

Uracil derivatives, such as commercial herbicides butafenacil and benzfendizone, have been identified as inhibitors of protoporphyrinogen oxidase (Protox, EC 1.3.3.4), one of the most important action targets of herbicides. In order to search for novel Protox inhibitors with high efficacy, broad‐spectrum activity, and safety to crops, commercially herbicide butafenacil was used as lead compound for further optimization; a series of title compounds 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j , 8k , 8l , 8m , 8n were designed and synthesized by introducing 1,3,4‐thiadiazole moiety into the uracil skeleton. The preliminary bioassays (in vitro) indicated that most of the target compounds displayed better inhibition against Echinochloa crus‐galli than Brassica campestris. The greenhouse bioassay results indicated that most of the compounds tested exhibited good‐to‐excellent herbicidal activities against B. campestris, A. retroflexus, E. crusgalli, and D. sanguinalis in pre‐emergence treatment at a dose of 1500 g/ha, for example, compound 8d showed 100% inhibition against the four plants tested in pre‐emergence treatment at a dose of 1500 g/ha. So, these types of skeletons can be used as valuable lead compounds for the development of a pre‐emergent herbicide.     

A Convenient Synthesis of Pyridophenanthroline Derivatives under Catalyst Free Conditions

A three‐component reaction between an aromatic aldehyde, quinolin‐6‐amine or quinolin‐5‐amine, and tert‐butyl 2,4‐dioxopiperidine‐1‐carboxylate in reflux EtOH gave pyrido phenanthroline derivatives in high yields under catalyst free conditions. The rare C‐H…F hydrogen bond is found in the crystal structure of 6h .