S2 General Procedures: Column chromatography was performed on silica gel, Acme grade 100-200 mesh. TLC plates were visualized either with UV, in an iodine chamber, or with phosphomolybdic acid spray, unless noted otherwise. Unless stated otherwise, all reagents were purchased from commercial sources and used without additional purification. THF was freshly distilled over Na-benzophenone ketyl. Melting points were uncorrected. Unless stated otherwise, 1 H NMR and 13 C NMR spectra were recorded either on a 400 MHz machine in CDCl 3 as solvent with TMS as reference unless otherwise indicated. Unless stated otherwise, all the reactions were performed under inert atmosphere. All the specific rotations were determined at 24 °C. (S,E)-ethyl 4-((tert butyldimethylsilyl)oxy)-2-ethylpent-2-enoate (12): To a stirred solution of the ester 10 (0.42 g, 1.80 mmol) in dry CH 2 Cl 2 (5 mL) was added DIBAL-H (1.0 M in toluene), (2.0 mL, 2.00 mmol) dropwise at-78 °C for a period of 5 minutes under argon atmosphere. The reaction mixture was stirred at the same temperature for 30 minutes. After completion of the reaction (TLC), it was quenched by the addition of a saturated aqueous solution of potassium sodium tartrate (15 mL), diluted with Et 2 O (10 mL) and stirred for one hour at room temperature. The aqueous layer was extracted with Et 2 O (2 × 10 mL). The combined organic layers were washed with brine (10 mL), dried over anhydrous Na 2 SO 4 and concentrated to yield the crude aldehyde which was used in the next step without further purification. To a stirred solution of the crude aldehyde (obtained above) in dry toluene (10 mL) was added phosphorane 11 (1.35 g, 3.60 mmol) under nitrogen atmosphere and the reaction mixture was refluxed for 8 h. After completion of the reaction (TLC), it was cooled to room temperature and most of the solvent was evaporated off. The crude residue thus obtained was purified by silica gel column chromatography using petroleum ether:CH 2 Cl 2 (7:3) as eluent to afford 12 (0.37 g, 73% for two steps) as a colourless oil. [α] D −2.6 (c 1.1, CHCl 3); IR (neat):
The enantiodivergent formal syntheses of both enantiomers of aspercyclide C is accomplished. Starting from L-(+)-tartaric acid, the key protected allylic alcohol, (3R,4R)-4-(methoxymethoxy)non-1-en-3-ol is prepared, and is then elaborated into both enantiomers of 3-[(4-methoxybenzyl)oxy]non-1-en-4-ol via Mitsunobu inversion. Esterification with a known biaryl acid, followed by ring-closing metathesis and deprotection completes the syntheses.
Synthesis of Azepino[4,5-b]indolones by an Intramolecular Cyclization of UnsaturatedTryptamides. -The seven step synthesis of the starting materials is described. Product (IId) is further transformed into the tetracyclic ABCD core structure of tronocarpine (XVII), and compound (IIb) is further converted into the tetracyclic scaffold of ibogamine (XVIII) and catharanthine (XIX). -(NIDHIRY, J.; PRASAD*, K. R.; Synlett 25 (2014) 18, 2585-2590, http://dx.
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