Photochemical Rearrangement of <i>N</i>-Chlorolactams: A Route to <i>N</i>-Heterocycles through Concerted Ring Contraction

Winter, Dana K.; Drouin, Alexandre; Lessard, Jean; Spino, Claude

doi:10.1021/jo100181h

Cited by 39 publications

(24 citation statements)

References 75 publications

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“…First of all, the double bond was selectively reduced through catalytic hydrogenation in the presence of Pd/C. Then, the amidic nitrogen of 13 was protected as Boc [27] and the piperidone was reduced to piperidine 15, using BH 3 •SMe 2 . This mild reducing agent was preferred to the most common LiAlH 4 , to avoid the conversion of the two Boc protecting groups into methyl amines [28].…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of (–)-Anaferine: A Further Ramification in a Diversity-Oriented Approach

et al. 2020

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The piperidine ring is a widespread motif in several natural bioactive alkaloids of both vegetal and marine origin. In the last years, a diversity-oriented synthetic (DOS) approach, aimed at the generation of a library of piperidine-based derivatives, was developed in our research group, employing commercially available 2-piperidine ethanol as a versatile precursor. Here, we report the exploration of another ramification of our DOS approach, that led us to the stereoselective total synthesis of (–)-anaferine, a bis-piperidine alkaloid present in Withania somnifera extract. This natural product was obtained in 9% overall yield over 13 steps, starting from a key homoallylic alcohol previously synthesised in our laboratory. Therefore, the collection of piperidine-derivatives accessible from 2-piperidine ethanol was enriched with a new, diverse scaffold.

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Section: Resultsmentioning

confidence: 99%

Total Synthesis of (–)-Anaferine: A Further Ramification in a Diversity-Oriented Approach

et al. 2020

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“…To access unprotecteda mino alcohols, other lactamsw ith readily deprotected groups, such as toluenes ulfonyl( Ts )a nd tert-butyloxycarbonyl (Boc), were then applied under the standard reaction conditions (see Ta ble 3). To our delight, lactams with Ts and Boc groups all led to quantitative results with different ring sizes (24)(25)(26)(27)(28). Furthermore,a fter as imple deprotection step (usually acid hydrolysis), free amino alcoholsc ould be produced in excellent yields, which demonstrates the great applicability of this protocol.…”

Section: Resultsmentioning

confidence: 99%

“…1 HNMR (400 MHz, CDCl 3 ): d = 3.78-3.69 (m, 2H), 2.50 (t, J = 8.1 Hz, 2H), 2.05-1.92 (m, 2H), 1.52 ppm (s, 9H). 1-(tert-Butoxycarbonyl)-2-oxopiperidine [26] Triethylamine (10 mmol), DMAP (1 mmol), and di-tert-butyl dicarbonate (15 mmol) were added to as tirred solution of lactam (10 mmol) in dichloromethane (20 mL), then the solution was stirred at RT for 3h.T he reaction was then concentrated under reduced pressure to give an orange semi-solid. The semi-solid was then taken up in dichloromethane and purified by using flash chromatography on silica gel to obtain aw hite crystalline solid.…”

Section: N-phenyllactammentioning

confidence: 99%

Ruthenium‐Pincer‐Catalyzed Hydrogenation of Lactams to Amino Alcohols

Chen

Wang

2018

Chemistry An Asian Journal

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By using the commercially available ruthenium pincer complex (Ru-MACHO-BH) as a catalyst, the challenging direct hydrogenation of lactams and analogues has been successfully accomplished to deliver corresponding value-added amino alcohols in good-to-excellent yields under mild reaction conditions. Remarkably, in addition to N-protected lactams, unprotected ones could also be readily reduced in the presence of a catalytic amount of weak base or even under neutral reaction conditions, which further highlights the broad substrate scope and the protocol efficiency.

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“…Characterization data of compounds 2a , 15a 2b , 12c 2c , 13 2e , 37 2i , 38 3a , 39 3b , 40 3c , 41 3d , 42 5a , 43 and 6 44 were previously reported and their spectral or HPLC confirmation are provided in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Catalytic Allylic Oxidation of Cyclic Enamides and 3,4-Dihydro-2H-Pyrans by TBHP

Humeidi

Alleyn

et al. 2017

J. Org. Chem.

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Allylic oxidation of heteroatom substituted cyclic alkenes by tert-butyl hydroperoxide (70% TBHP in water) using catalytic dirhodium caprolactamate [Rh2(cap)4] forms enone products with a variety of 2-substituted cyclic enamides and 3,4-dihyro-2H-pyrans. These reactions occur under mild reaction conditions, are operationally convenient to execute, and are effective for product formation with as low as 0.25 mol% catalyst loading. With heteroatom stabilization of the intermediate allylic free radical two sites for oxidative product formation are possible, and the selectivity of the oxidative process varies with the heteroatom when R = H. Cyclic enamides produce 4-piperidones in good yields when R = alkyl or aryl, but oxidation of 2H-pyrans also gives alkyl cleavage products. Alternative catalysts for TBHP oxidations show comparable selectivities but give lower product yields.

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Photochemical Rearrangement of N-Chlorolactams: A Route to N-Heterocycles through Concerted Ring Contraction

Cited by 39 publications

References 75 publications

Total Synthesis of (–)-Anaferine: A Further Ramification in a Diversity-Oriented Approach

Total Synthesis of (–)-Anaferine: A Further Ramification in a Diversity-Oriented Approach

Ruthenium‐Pincer‐Catalyzed Hydrogenation of Lactams to Amino Alcohols

Catalytic Allylic Oxidation of Cyclic Enamides and 3,4-Dihydro-2H-Pyrans by TBHP

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