16635-18-0Relevant articles and documents
Stereoselective reduction of flavanones by marine-derived fungi
Birolli, Willian G.,Nitschke, Marcia,Porto, André Luiz M.,Santos, Darlisson de A.,de Matos, Iara L.
, (2021/08/13)
Biotransformation is an alternative with great potential to modify the structures of natural and synthetic flavonoids. Therefore, the bioreduction of synthetic halogenated flavanones employing marine-derived fungi was described, aiming the synthesis of flavan-4-ols 3a-g with high enantiomeric excesses (ee) of both cis- and trans-diastereoisomers (up to >99% ee). Ten strains were screened for reduction of flavanone 2a in liquid medium and in phosphate buffer solution. The most selective strains Cladosporium sp. CBMAI 1237 and Acremonium sp. CBMAI1676 were employed for reduction of flavanones 2a-g. The fungus Cladosporium sp. CBMAI 1237 presented yields of 72–87% with 0–64% ee cis and 0–30% ee trans with diastereoisomeric ratio (dr) from 52:48 to 64:36 (cis:trans). Whereas Acremonium sp. CBMAI 1676 resulted in 31% yield with 77–99% ee of the cis and 95–99% ee of the trans-diastereoisomers 3a-g with a dr from 54:46 to 96:4 (cis:trans). To our knowledge, this is the first report of the brominated flavon-4-ols 3e and 3f. The use of fungi, with emphasis for these marine-derived strains, is an interesting approach for enantioselective reduction of halogenated flavanones. Therefore, this strategy can be explored to obtain enantioenriched compounds with biological activities.
Substituent-Controlled Divergent Cascade Cycloaddition Reactions of Chalcones and Arylalkynols: Access to Spiroketals and Oxa-Bridged Fused Heterocycles
Chang, Weixing,Kong, Jingyang,Li, Jing,Liu, Lingyan,Wang, Hongkai,Zeng, Tianlong
supporting information, p. 4024 - 4032 (2021/07/12)
Herein, we report substituent-controlled divergent cascade cycloaddition reactions of chalcones and arylalkynols in the presence of PtI2. Depending on the substituent on the chalcone, either spiroketals or oxa-bridged fused heterocycles could be obtained in the ranges of 86–97% and 87–95% yields under identical reaction conditions. Control experiments were carried out to elucidate the origin of the high chemoselectivity. These provide a method for the synthesis of a diverse array of structurally complex oxygen-containing heterocycles. (Figure presented.).
Synthesis and kinetic study for the interconversion process of some 2'-hydroxychalcones to their corresponding flavanones
Majed, Zainab Waleed,Said, Said Abdelqader,Shareef, Omar Adil
, p. 4379 - 4386 (2020/12/09)
In this work, five substituted2'-Hydroxychalconeswere prepared using Claisen - Schmidt condensation and used as a synthone for substituted flavanones via base catalyzed isomerization process. The latter process has been studied kinetically using HPLC technique in (8:2) (CH3CN:CH3OH) medium at different temperatures (298 K - 318 K). The obtained results were inconsonance with a four-step mechanism which considered the existence of phenoxide ion as the key intermediate. The reaction was achieved as a pseudo first order reaction in which the rate of the studied compounds followed the sequence 1>2>3>4>5, and the activation energy had the same sequence for these compounds. The reaction rate was affected by the electronic behavior of the different substituents at ring B since they played an important role in the stability of the intermediate that led to the final product.
