An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one-pot step-wise reactions involving 2-hydroxycinnamaldehydes,2-aminochalcones,and mal...An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one-pot step-wise reactions involving 2-hydroxycinnamaldehydes,2-aminochalcones,and malononitrile as substrates.The reactions underwent a quintuple process by aza-Michael/Michael/Knoevenagel/oxa-Michael/aldol-type reaction in sequence to give products bearing 3 new generated rings and 5 chiral centers in moderate to quantitative yields with excellent stereoselectivities.展开更多
This study aimed to investigate the relaxant effect of chroman compound HEF-04 on isolated vascular smooth muscle （VSM） and the possible underlying mechanisms involved. Isolated rabbit thoracic aorta was used as the...This study aimed to investigate the relaxant effect of chroman compound HEF-04 on isolated vascular smooth muscle （VSM） and the possible underlying mechanisms involved. Isolated rabbit thoracic aorta was used as the in vitro model and the relaxant effects of HEF-04 on endothelium-intact （＋EC） and endothelium-denuded （EC） thoracic aortic rings were compared. Potassium channel blockers, guanylate cyclase inhibitors, and COX-inhibitors were used to explore associations between the relaxant effects of HEF-04 with potassium channels, NO, and prostaglandin-like substances and endothelial hyperpolafizing factor （EDHF）, respectively. The results indicated that HEF-04 （1 × 10^-5 mol/L to 3× 10^-3 mol/L） had no significant impact on basal vascular tension, but could relax the contraction of vascular smooth muscle caused by high-K＋ solution in a dose-dependent manner. Indomethacin （5.6× 10^-6 mol/L） had no effect on vasorelaxation effect of HEF-04. In contrast, the vasorelaxant effect of HEF-04 was enhanced by methylene blue, which was significantly inhibited by calcium-dependent potassium channel blocker TEA. The vasorelaxant effect of HEF-04 on ＋EC thoracic aortic rings was significantly stronger than that on -EC thoracic aortic rings. The endothelium dependent relaxant effect of HEF-04 on VSM might be attributed to the interaction of HEF-04 with vascular relaxing factors or the increased release of EDHF.展开更多
The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and st...The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and studied. There is a close relationship between the distribution of methylatd chromans and paleosalinity of depositional environment. In the Eq1-Eq3 source rocks deposited under hypersaline environment with lower Pr/Ph ratio,higher gammacerane index and abundant organic sulfur-containing compounds,methyl MTTC and dimethyl MTTC are main components,but in the Eq4 source rocks deposited non-hypersaline environment with relatively higher Pr/Ph ratio,lower gammacerane index and organic sulfur-containing compounds,trimethyl MTTC is a major compound in methylate chromans. Obviously,the distributions and the compositions of methylated chromans in the source rocks are in harmony with biomarker indicators indicating the paleaosalinity and redox of depositional environment. The relationship between the ratio of 5,8-dimethyl MTTC to 7,8-dimethyl MTTC(dimethyl MTTC ratio) and the maturity of organic matter in the source rocks from Mingjia 1 well has been discussed. The results show that dimethyl MTTC ratio increased with the burial depth and the maturation of organic matter in the source rocks,especially in immature level. It is noteworthy that this ratio is very susceptible to small variation in the maturity of organic matter in the source rocks when vitrinite reflectance Ro is less than 0.65%. It may imply that this ratio is a good and susceptible aromatic maturity indicator for the relative maturity of organic matter in immature source rocks.展开更多
A hexafluoroisopropanol(HFIP)-catalyzed highly diastereoselective formal[4+2]cyclization between ortho-hydroxyphenyl para-quinone methides and difluoroenoxysilanes is developed.This tandem protocol provides a simple a...A hexafluoroisopropanol(HFIP)-catalyzed highly diastereoselective formal[4+2]cyclization between ortho-hydroxyphenyl para-quinone methides and difluoroenoxysilanes is developed.This tandem protocol provides a simple and straightforward approach to assemble diverse multiply functionalized difluorinated chromans with high to excellent diastereoselectivity by employing difluoroenoxysilane as a new C2 synthon.展开更多
Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselec...Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities(up to 99%yield,98%ee).Moreover,the gram-scale hydrogenation could be performed well in the presence of 0.02 mol%catalyst loading(TON=5000),the hydrogenation product was easily converted to access other important compounds,which demonstrated the synthetic utility of this asymmetric catalytic methodology.展开更多
An expedient and mild strategy for the synthesis of unconventional 2-（dimethylamino）-3,3-difluorochroman-4-one derivatives from o-hydroxyarylenaminones and Selectfluor was developed at room temperature under catalys...An expedient and mild strategy for the synthesis of unconventional 2-（dimethylamino）-3,3-difluorochroman-4-one derivatives from o-hydroxyarylenaminones and Selectfluor was developed at room temperature under catalyst-free conditions. This method showed excellent chemoselectivity and great functional groups tolerance.展开更多
Significantly high abundant methyl-Methyl Trimethyl Tridecyl Chromans （MTTCs） have been detected in aromatic hydrocarbon fractions in crude oils from the Jizhong Depression and Jianghan Basin. The distribution of th...Significantly high abundant methyl-Methyl Trimethyl Tridecyl Chromans （MTTCs） have been detected in aromatic hydrocarbon fractions in crude oils from the Jizhong Depression and Jianghan Basin. The distribution of these compounds is dominated by methyl-MTTC and dimethyl- MTTC series, which indicate diagenetic products of a hypersaline depositional environment in the early stage and show a low degree of methylation. The occurrence of significantly high abundant methyl-MTTC depends mainly on good preservation conditions with a strongly reductive, hypersaline and water-columned depositional environment and subsequent non-intensive diagenetic transformations. The stable carbon isotopic compositions of the methyl-MTTCs and dimethyl-MTTCs in two samples are far different from the stable carbon isotopic composition of C30 hopane of apparent bacteria biogenesis （up to 4.11‰ and 5.75‰, respectively）. This obviously demonstrates that the methyl-MTTC and dimethyl-MTTCs cannot be of bacteria origin, which is different from the previous point of view about non-photosynthetic bacteria products or possible bacteria-reworked products. On the contrary, the stable carbon isotopic compositions of methyl-MTTC and dimethyl-MTTCs in the two samples were similar to that of the same carbon-numbered n-alkanes （nC27-nC28-nC29）, which indicates that they share the same source origin. Especially in the crude oil from the Zhao61 well, stable carbon isotopic compositions are also similar to that of the same carbon-numbered steranes with ααα- 20R isomer （mostly less than 0.4‰）. In consideration of the results of previous studies on saline lake ecological sedimentation, the authors hold that the methyl-MTTC and dimethyl-MTTCs in the saline lake sediments should be of algal biogenesis origin.展开更多
基金supported by the Advanced Talents Incubation Program of Hebei University(521000981411)the National Nature Science Foundation of China(82273792),Science Research Project of Hebei Education Department(QN2021023)+2 种基金the Natural Science Interdisciplinary Research Program of Hebei_University(DXK201913)High-throughput Intelligent Integrated Lung Cancer Targeted Drug Development Innovation Team Project(IT2023c01)the Excellent Youth Research Innovation Team of Hebei University(QNTD202406).
文摘An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one-pot step-wise reactions involving 2-hydroxycinnamaldehydes,2-aminochalcones,and malononitrile as substrates.The reactions underwent a quintuple process by aza-Michael/Michael/Knoevenagel/oxa-Michael/aldol-type reaction in sequence to give products bearing 3 new generated rings and 5 chiral centers in moderate to quantitative yields with excellent stereoselectivities.
文摘This study aimed to investigate the relaxant effect of chroman compound HEF-04 on isolated vascular smooth muscle （VSM） and the possible underlying mechanisms involved. Isolated rabbit thoracic aorta was used as the in vitro model and the relaxant effects of HEF-04 on endothelium-intact （＋EC） and endothelium-denuded （EC） thoracic aortic rings were compared. Potassium channel blockers, guanylate cyclase inhibitors, and COX-inhibitors were used to explore associations between the relaxant effects of HEF-04 with potassium channels, NO, and prostaglandin-like substances and endothelial hyperpolafizing factor （EDHF）, respectively. The results indicated that HEF-04 （1 × 10^-5 mol/L to 3× 10^-3 mol/L） had no significant impact on basal vascular tension, but could relax the contraction of vascular smooth muscle caused by high-K＋ solution in a dose-dependent manner. Indomethacin （5.6× 10^-6 mol/L） had no effect on vasorelaxation effect of HEF-04. In contrast, the vasorelaxant effect of HEF-04 was enhanced by methylene blue, which was significantly inhibited by calcium-dependent potassium channel blocker TEA. The vasorelaxant effect of HEF-04 on ＋EC thoracic aortic rings was significantly stronger than that on -EC thoracic aortic rings. The endothelium dependent relaxant effect of HEF-04 on VSM might be attributed to the interaction of HEF-04 with vascular relaxing factors or the increased release of EDHF.
基金Supported by Key Technologies R & D Programme (Grant No. 2004BA616A02-04-02-01)
文摘The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and studied. There is a close relationship between the distribution of methylatd chromans and paleosalinity of depositional environment. In the Eq1-Eq3 source rocks deposited under hypersaline environment with lower Pr/Ph ratio,higher gammacerane index and abundant organic sulfur-containing compounds,methyl MTTC and dimethyl MTTC are main components,but in the Eq4 source rocks deposited non-hypersaline environment with relatively higher Pr/Ph ratio,lower gammacerane index and organic sulfur-containing compounds,trimethyl MTTC is a major compound in methylate chromans. Obviously,the distributions and the compositions of methylated chromans in the source rocks are in harmony with biomarker indicators indicating the paleaosalinity and redox of depositional environment. The relationship between the ratio of 5,8-dimethyl MTTC to 7,8-dimethyl MTTC(dimethyl MTTC ratio) and the maturity of organic matter in the source rocks from Mingjia 1 well has been discussed. The results show that dimethyl MTTC ratio increased with the burial depth and the maturation of organic matter in the source rocks,especially in immature level. It is noteworthy that this ratio is very susceptible to small variation in the maturity of organic matter in the source rocks when vitrinite reflectance Ro is less than 0.65%. It may imply that this ratio is a good and susceptible aromatic maturity indicator for the relative maturity of organic matter in immature source rocks.
基金the financial support from the Natural Science Foundation of Zhejiang Province(No.LQ20B020005)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2019R01005)Joint Fund of Zhejiang Provincial Natural Science Foundation(No.LTZ21B020001)。
文摘A hexafluoroisopropanol(HFIP)-catalyzed highly diastereoselective formal[4+2]cyclization between ortho-hydroxyphenyl para-quinone methides and difluoroenoxysilanes is developed.This tandem protocol provides a simple and straightforward approach to assemble diverse multiply functionalized difluorinated chromans with high to excellent diastereoselectivity by employing difluoroenoxysilane as a new C2 synthon.
基金the National Natural Science Foundation of China(Nos.21432007,21502145,21602172)Wuhan Morning Light Plan of Youth Science and Technology(No.2017050304010307)+4 种基金the Fundamental Research Funds for and the Central Universities(No.2042018kf0202)Shenzhen Nobel Prize Scientists Laboratory Project(No.C17783101)Science and Technology Innovation Committee of Shenzhen(No.KQTD 20150717103157174)SZDRC Discipline Construction ProgramThe Program of Introducing Talents of Discipline to Universities of China(111 Project)。
文摘Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities(up to 99%yield,98%ee).Moreover,the gram-scale hydrogenation could be performed well in the presence of 0.02 mol%catalyst loading(TON=5000),the hydrogenation product was easily converted to access other important compounds,which demonstrated the synthetic utility of this asymmetric catalytic methodology.
基金Financial support from the Recruitment Program of Global Experts (1000 Talents Plan)the Natural Science Foundation of Fujian Province (No. 2016J01064)+1 种基金Fujian Hundred Talents Plan, Program of Innovative Research Team of Huaqiao University (No. Z14X0047)Subsidized Project for Cultivating Postgraduates’ Innovative Ability in Scientific Research of Huaqiao University (for Z. Kuang) are gratefully acknowledged
文摘An expedient and mild strategy for the synthesis of unconventional 2-（dimethylamino）-3,3-difluorochroman-4-one derivatives from o-hydroxyarylenaminones and Selectfluor was developed at room temperature under catalyst-free conditions. This method showed excellent chemoselectivity and great functional groups tolerance.
文摘Significantly high abundant methyl-Methyl Trimethyl Tridecyl Chromans （MTTCs） have been detected in aromatic hydrocarbon fractions in crude oils from the Jizhong Depression and Jianghan Basin. The distribution of these compounds is dominated by methyl-MTTC and dimethyl- MTTC series, which indicate diagenetic products of a hypersaline depositional environment in the early stage and show a low degree of methylation. The occurrence of significantly high abundant methyl-MTTC depends mainly on good preservation conditions with a strongly reductive, hypersaline and water-columned depositional environment and subsequent non-intensive diagenetic transformations. The stable carbon isotopic compositions of the methyl-MTTCs and dimethyl-MTTCs in two samples are far different from the stable carbon isotopic composition of C30 hopane of apparent bacteria biogenesis （up to 4.11‰ and 5.75‰, respectively）. This obviously demonstrates that the methyl-MTTC and dimethyl-MTTCs cannot be of bacteria origin, which is different from the previous point of view about non-photosynthetic bacteria products or possible bacteria-reworked products. On the contrary, the stable carbon isotopic compositions of methyl-MTTC and dimethyl-MTTCs in the two samples were similar to that of the same carbon-numbered n-alkanes （nC27-nC28-nC29）, which indicates that they share the same source origin. Especially in the crude oil from the Zhao61 well, stable carbon isotopic compositions are also similar to that of the same carbon-numbered steranes with ααα- 20R isomer （mostly less than 0.4‰）. In consideration of the results of previous studies on saline lake ecological sedimentation, the authors hold that the methyl-MTTC and dimethyl-MTTCs in the saline lake sediments should be of algal biogenesis origin.
