- Facile access to chiral 4-substituted chromanes through Rh-catalyzed asymmetric hydrogenation
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Rh/ZhaoPhos-catalyzed asymmetric hydrogenation of a series of (E)-2-(chroman-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities (up to 99percent yield, 98percent ee). Moreover, the gram-scale hydrogenation could be performed well in the presence of 0.02 molpercent 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.
- Tao, Lin,Zhao, Qingyang,Zhang, Xumu,Dong, Xiu-Qin
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supporting information
p. 1859 - 1862
(2020/01/21)
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- Synthesis of Flavanones via Palladium(II)-Catalyzed One-Pot β-Arylation of Chromanones with Arylboronic Acids
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A total of 47 flavanones were expediently synthesized via one-pot β-arylation of chromanones, a class of simple ketones possessing chemically unactivated β sites, with arylboronic acids via tandem palladium(II) catalysis. This reaction provides a novel route to various flavanones, including natural products such as naringenin trimethyl ether, in yields up to 92percent.
- Cho, Yang Yil,Jang, Hyu Jeong,Kim, Dong Hwan,Kim, Nam Yong,Kim, Nam-Jung,Kim, Young Min,Lee, Soo Jin,Lee, Yong Sup,Park, Boyoung Y.,Son, Seung Hwan,Yoo, Hyung-Seok
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supporting information
p. 10012 - 10023
(2019/08/30)
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- Studies towards the stereoselective α-hydroxylation of flavanones. Biosynthetic significance
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The enolates of various propiophenones, chromanones, and also analogues of naturally occurring flavanones were stereoselectively hydroxylated at the ?-position, by employing commercially available enantiopure oxaziridines, to afford the desired ?-hydroxylated target molecules in good to exceptional stereoselectivities and in moderate to good chemical yields. A mechanistic rationale is presented to account for the stereoselectivities achieved. These in vitro results were tentatively related to the stereoselective biosynthesis of enantio-enriched dihydroflavonols while questions were raised about the authenticity of certain natural compounds. CSIRO 2008.
- Border, Zola-Michele,Marais, Charlene,Bezuidenhoudt, Barend C. B.,Steenkamp, Jacobus A.
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p. 122 - 130
(2008/04/11)
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- A NEW SYNTHETIC APPROACH TO THE ROTENOID RING SYSTEM
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The (+)-cis-chromanochromanones (2) and (3), respresenting the basic ring system of the natural insecticide rotenone, have been synthesised by a general procedure; the key step is 4-aroylation of the 4-(phenyl-sulphonyl)chromans (7; Z=SO2Ph).
- Lai, Steven M. F.,Orchison, Jack J. A.,Whiting, Donald A.
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p. 5895 - 5906
(2007/10/02)
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- Studies in Antifertility Agents: Part XXIX - synthesis of 4--3-benzylchromans
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7-H/Methoxy-4-chromanones (1, 2), obtained by PPA cyclization of the respective β-aryloxypropionic acids, on treatment with araldehydes (3, 4) give the corresponding 3-arylidene-4-chromanones (5, 6).Catalytic hydrogenation of 5 and 6 over Pd-C (10percent) with one mole of hydrogen affords 3-benzyl-4-chromanones (7, 8), while hydrogenation of 6 yields 3-benzyl-7-methoxychroman (9).NaBH4 reduction of 7 and 8 gives the corresponding 4-chromanols (10, 11) as a mixture of 3,4-cis- and -trans-isomers, which are arylated as such with PhOH-AlCl3 to give 4-(p-hydroxyphenyl)chromans(12, 13) as the main products.Treatment of 12 and 13 with Ac2O-pyridine and with p-NO2C6H4COCl-pyridine yields the corresponding p-acetoxy (14, 15) and p-nitrobenzoyloxy (16, 17) derivatives.Alkylation of 12 and 13 with N-(β-chloroethyl)pyrrolidine hydrochloride furnishes the title compounds, 4--3-(p-chloro/H)benzyl-7-H/methoxy-chromans (18, 19).None of these compounds prevents pregnancy at 5 mg/kg dose in rats.
- Sangwan, Naresh K.,Rastogi, Shri Nivas
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p. 500 - 503
(2007/10/02)
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