Tricyclic benzomorphan analogues by intramolecular Oxa-Pictet-Spengler reaction

Wünsch, Bernhard; Zott, Matthias

doi:10.1016/s0957-4166(00)80089-0

Cited by 8 publications

(3 citation statements)

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“…It is a powerful and well-developed C–C bond forming approach to complex molecules, including natural products . Jacobsen et al reported a chiral thiourea catalyzed asymmetric acyl-Pictet–Spengler reaction, and subsequently, our group developed a Brønsted acid catalyzed enantioselective Pictet–Spengler reaction. , In the analogous oxa-Pictet–Spengler reaction, aryl ethanols react with carbonyl compounds to give 1-substituted isochromans …”

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confidence: 99%

Nitrated Confined Imidodiphosphates Enable a Catalytic Asymmetric Oxa-Pictet–Spengler Reaction

et al. 2016

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The development of a highly enantioselective catalytic oxa-Pictet-Spengler reaction has proven a great challenge for chemical synthesis. We now report the first example of such a process, which was realized by utilizing a nitrated confined imidodiphosphoric acid catalyst. Our approach provides substituted isochroman derivatives from both aliphatic and aromatic aldehydes with high yields and excellent enantioselectivities. DFT calculations provide insight into the reaction mechanism.

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confidence: 99%

Nitrated Confined Imidodiphosphates Enable a Catalytic Asymmetric Oxa-Pictet–Spengler Reaction

et al. 2016

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“…Typically, aqueous HCl [25] as well as BF 3 ·Et 2 O, [26] HCl gas, [27] TsOH, [28] ZnCl 2 , [29] AlCl 3 , [30] TiCl 4 [31] and SnCl 4 [32] in organic solvents have been used to promote the reaction, sometimes along with high reaction temperatures. However, more recently some new and milder promoters and conditions have been described; for example, the use of catalytic amounts of TsOH in MeOH at 4°C, [33] oleic acid in MeOH at 21°C, or using dehydrating agents (molecular sieves or anhydrous Na 2 SO 4 ) besides the promoter.…”

Section: New Promoters and New Reaction Control Elementsmentioning

confidence: 99%

Synthesis of Oxacycles Employing the Oxa‐Pictet–Spengler Reaction: Recent Developments and New Prospects

2011

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The oxa‐Pictet–Spengler cyclization is the oxygen variation of the Pictet–Spengler reaction, in which an aromatic alcohol component (generally a β‐arylethyl alcohol) reacts with acarbonyl component (aldehyde, ketone or their masked derivatives), to yield a 1‐substituted (or 1,1′‐disubstituted)pyran fused to the aromatic ring system found in the starting alcohol. The transformation is usually promoted by Brønsted and Lewis acids. Intramolecular versions of the reaction are also known, where both components are mutually masked as an acetal. Discussed here are aspects concerning the most recent developments and new applications of this useful reaction, including the scope and limitations of new promoters, and new mechanistic pictures of this transformation. The use of novel stereochemical control strategies and the application of the reaction to the synthesis of natural products and their analogs, as well as to accessing fully synthetic bioactive compounds and new ring systems are presented, and chiral versions of the oxa‐Pictet–Spengler are also analyzed.

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“…At this juncture, it was decided to explore the possibility of using in 4 N HCl in 1,4-dioxane solvent system at room temperature which at last furnished the desired transformation smoothly. 13 After the completion of reaction (monitored by TLC) the reaction mixture was made basic by treatment with NaHCO 3 and the crude was obtained as a white solid which was filtered and purified using MeOH/CHCl 3 as eluent in column chromatography, to furnish the target compound 1, fellutamide B in 95% yield in pure form. The spectroscopic data and optical rotation obtained for 1 were in agreement with the reported literature.…”

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confidence: 99%