- First total synthesis of medicinally important 3,4,7-trimethoxy-9,10-dihydrophenanthrene-1,5-diol
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The first total synthesis was successfully achieved for biologically active 9,10-dihydrophenanthrene-1,5-diol. The key features of our synthetic approach are Perkin condensation, followed by bromination, palladium mediated intramolecular C-C bond coupling, and selective isopropyl ether cleavage. Synthesized compounds were purified and characterized by IR, 1HNMR, 13CNMR and HRMS/LC-MS.
- Gangireddy Venkata, Sivarami Reddy,Narkhede, Umesh C.,Jadhav, Vinod D.,Gangu Naidu, Ch.
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p. 1670 - 1673
(2018/03/29)
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- Synthesis of Lamellarin G Trimethyl Ether by von Miller–Pl?chl-Type Cyclocondensation
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A concise synthesis of lamellarin G trimethyl ether based on a von Miller–Pl?chl-type cyclocondensation of a deprotonated α-amino nitrile with an α,β-unsaturated ketone as the key step was developed. The general strategy does not rely on molecular symmetry and allows for the independent variation of the substitution pattern.
- Colligs, Vanessa C.,Dialer, Clemens,Opatz, Till
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p. 4064 - 4070
(2018/07/31)
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- Anomalous substituent effects in the Bischler-Napieralski reaction of 2-aryl aromatic formamides
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Treatment of some 1-naphthylformamides (or formanilides) possessing a 2,4,5-trioxygenated phenyl substituent at the 2-position with POCl3 caused an unprecedented carbon insertion reaction into a benzene ring, producing 7-5 ring (azaazulene) systems as valence isomers of isoquinoline skeletons. Precise examination of this abnormal Bischler-Napieralski reaction (BNR) using various substrates led to the following scope and limitations: (i) the 7-5 ring systems were constructed when either 2-alkoxy-4,5-methylenedioxyphenyl- or 4,5-dialkoxy-2-hydroxyphenyl-substituted formamides were used as a starting substrate; (ii) in the former case the formyl carbon was inserted into the C1-C6 bond of the 2-phenyl group, and normal isoquinoline cyclization competed with an abnormal carbon insertion reaction; (iii) the presence of a hydroxy group at the 2′-position as in the latter cases caused exclusive carbon insertion, in which alternative C1-C2 insertion products were quantitatively formed; (iv) 3,6-dimethoxy-2-hydroxyphenyl-substituted formanilide electronically equivalent to 4,5-dialkoxy-2-hydroxy derivatives produced an indole-pyrone as an abnormal BNR product. Theoretical approaches using the PM-3 method indicated that these abnormal BNRs could be triggered by ipso attack at the 1′-position yielding spiro intermediates. Ring cleavege of the six-membered ring in the spiro intermediates to a ketene function followed by recyclization was proposed for the 2′-hydroxy-directed abnormal BNRs leading to the C1-C2 insertion product or the indole-pyrone derivative.
- Ishikawa,Shimooka,Narioka,Noguchi,Saito,Ishikawa,Yamazaki,Harayama,Seki,Yamaguchi
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p. 9143 - 9151
(2007/10/03)
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