- Towards the Sarpagine-Ajmaline-Macroline Family of Indole Alkaloids: Enantioselective Synthesis of an N-Demethyl Alstolactone Diastereomer
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the strategy involving the use of functionalized tetrahydro-6H-cycloocta[b]indol-6-one is reported as a key intermediate for synthesis of members of the sarpagine-ajmaline-macroline family of monoterpene indole alkaloids. The desired tricycle was synthesized through the following key steps: 1) Evans’ syn-selective aldolization; 2) Liebeskind–Srogl cross-coupling using the phenylthiol ester of 3-chloropropanoic acid as a surrogate of acrylic thioester for the synthesis of 2,3-disubstituted indoles; and 3) ring-closing metathesis (RCM) for the formation of the eight-membered ring. An N-allylation followed by intramolecular 1,4-addition was planned for synthesis of the vobasine class of natural products. However, attempted cyclizations under a diverse set of conditions involving anionic, radical, and organopalladium/organonickel species failed to produce the bridged ring system. On the other hand, esterification of the pendant primary alcohol function with acetoacetic acid, followed by intramolecular Michael addition, afforded the desired tetracycle with excellent diastereoselectivity. Subsequent functional group manipulation and transannular cyclization of the amino alcohol afforded the N(1)-demethyl-3,5-diepi-alstolactone. We believe that the same synthetic route would afford the alstolactone should the amino alcohol with appropriate stereochemistry be used as the starting material.
- Dagoneau, Dylan,Wang, Qian,Zhu, Jieping
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supporting information
p. 4866 - 4873
(2020/04/15)
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- Fluorination process
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Compounds of formula (II), (IIIa) or (IIIb) (variables are described in the specification) are prepared by fluorination of β,γ-unsaturated alkyl silanes. These compounds are useful as building blocks in the pharmaceutical industry.
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Page/Page column 12
(2008/06/13)
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- Synthesis of novel enantiopure fluorinated building blocks from acyclic chiral allylsilanes
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(Chemical Equation Presented) Homochiral β-fluorinated γ,δ-unsaturated carboxylic acids with an allylic fluorinated stereogenic center are available from the corresponding enantiopure allylsilanes. The key step for introduction of the fluorine substituent
- Tredwell, Matthew,Tenza, Kenny,Pacheco, Ma. Carmen,Gouverneur, Veronique
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p. 4495 - 4497
(2007/10/03)
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- 2-OXAZOLIDINONES AND THEIR USE AS INHIBITORS OF ANIMAL CELL MOTILITY AND GROWTH
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Cell motility and growth inhibitors, including compounds of the general structural formula (I), and use of the cell motility and cell growth inhibitors, and pharmaceutically acceptable salts, pro-drugs, and solvates thereof, as therapeutic agents, are disclosed.
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- Attractant for the mediterranean fruit fly, the method of preparation and method of use
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A method of attracting the Mediterranean fruit fly by subjecting the Mediterranean fruit fly to an attractant, wherein the attractant is ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of >5:1. The compound ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate, in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of >5:1, may be stereoselectively synthesized on a multigram scale in 15% yield by reacting ethyl (1R,2R,5S)-5-hydroxy-2-methyl-1-carboxylate with Ph3P-imidazole-I2(or Ph3P-2,6-lutidine-I2) in a carbon tetrachloride/methlylene chloride mixture. The 1R,2R,5R enantiomer is significantly more attractive than its enantiomeric counterpart (1S,2S,5S), or either of the commercial products trimedlure or ceralure, each a mixture of 16 regio and stereoisomers.
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- Diastereoselective synthesis of α-substituted β-amidophosphonates
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A simple and general asymmetric synthesis of β-amidophosphonates is described. The method involves the highly selective addition (up to 95% d.e.) of diethyl phosphite to various chiral α,β-unsaturated carboxylic amides derived from chiral aminoalcohols.
- Castelot-Deliencourt, Géraldine,Pannecoucke, Xavier,Quirion, Jean-Charles
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p. 1025 - 1028
(2007/10/03)
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- Enantioselective synthesis of ceralure B1, ethyl cis-5-iodo-trans-2- methylcyclohexane-1-carboxylate
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Ethyl (1R, 2R, 5R)-5-iodo-2-methylcyclohexane-1-carboxylate is a potent attractant for the Mediterranean fruit fly. This compound was stereoselectively synthesized on a multigram scale in nine steps in 15% yield. Key steps of the synthesis involved an asymmetric Diels-Alder reaction, iodolactonization, stereoselective reduction of the carbonyl, and inversion of configuration with iodide. (C) 2000 Elsevier Science Ltd.
- Raw, Andre S.,Jang, Eric B.
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p. 3285 - 3290
(2007/10/03)
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- Process of synthesizing n-acyl auxiliaries
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A process of synthesizing N-acyl auxiliary compounds is disclosed. A compound of the formula: STR1 is reacted with an anhydride in the presence of a lithium salt and an amine base to produce the N-acylated auxiliary.
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- A practical method for N-acylation of bornane-2,10-sultam and 2-oxazolidinones
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The N-trimethylsilyl derivatives of (+)-bornane-2,10-sultam (10,10-dimethyl-5-thia-4-azatricyclo[5.2.1.03,7]decane 5,5-dioxide) and (R)-4-benzyl-2-oxazolidinone and 4-methyl-5-phenyl-2-oxazolidinone react with acid chlorides in refluxing benzen
- Thom,Kocienski
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p. 582 - 586
(2007/10/02)
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