Asymmetric synthesis of cyclo-archaeol and β-glucosyl cyclo-archaeol

Ferrer, Catalina; Fodran, Peter; Barroso, Santiago; Gibson, Robert; Hopmans, Ellen C.; Damsté, Jaap Sinninghe; Schouten, Stefan; Minnaard, Adriaan J.

doi:10.1039/c3ob27277j

Cited by 17 publications

(26 citation statements)

References 54 publications

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“…These compared favorably to the spectra of the prior sample, 4a but as expected did not provide information about isomer identity or purity. A new set of spectra was then recorded at 700 MHz for 1 H and 175 MHz for 13 C, and the data sets were processed by the Traficante algorithm 13 for resolution enhancement.…”

Section: Resultsmentioning

confidence: 81%

“…4a,11 The late stages of this synthesis are summarized in Scheme 1, while the Supporting Information provides complete information on reagents and yields in Schemes S1 and S2. All five of the stereocenters in penultimate intermediates 4 and 5 were synthesized by asymmetric conjugate additions reactions in with high levels of stereoselectivity (>95%).…”

Section: Resultsmentioning

confidence: 99%

“…Of the two remaining configurations, all stereocenters ( R ) or all-( S ), the results of the bio-assays support the all-( S ) assignment of 2 . 4a,5 In addition, the crystal structure of CD1c bound to all-( S )-MPM 2 has been reported recently. 7 However, assignment of the absolute configuration as all-( S ) contradicts a predictive model by Leadley and co-workers.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Analysis of the All-(S) Side Chain of Phosphomycoketides: A Test of NMR Predictions for Saturated Oligoisoprenoid Stereoisomers

et al. 2013

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(4S,8S,12S,16S,20S)-Pentamethylheptacosan-1-ol has been synthesized and analyzed by resolution-enhanced NMR spectroscopy with the aid of a recent set predicted spectra of all its stereoisomers. The configuration was confirmed but isomer purity of the sample (~70%) was lower than expected. A truncated analog, (2S,6S,10S,14S)-2,6,10,14-tetramethylhenicosan-1-ol TBDPS ether, was prepared from a late stage synthetic intermediate. Analysis of its spectra confirmed the configuration and showed that the sample was isomerically pure. The results suggest that a late-stage epimerization, not a failure of an asymmetric synthesis step, caused the formation of minor stereoisomers in the sample of pentamethylheptacosan-1-ol. The study shows the value of the predicted set of oligoisoprenoid spectra and further extends the predictive model to a new subclass of compounds.

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Section: Resultsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and Analysis of the All-(S) Side Chain of Phosphomycoketides: A Test of NMR Predictions for Saturated Oligoisoprenoid Stereoisomers

et al. 2013

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“…In fact Feringa, Minnaard, and Negishi have published excellent chemistry in an attempt to address this problem. Recently, Minnaard described the total synthesis of a deoxypropionate chain used in the study of new antibiotics for Gram‐negative bacteria . Sufficient quantities of the desired products are required to establish the relative and absolute configuration of many kinds of these natural products, as their structure is still not known or not completely assigned .…”

Section: Discussionmentioning

confidence: 99%

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

et al. 2014

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Recently, the direct substitution of allylic, benzylic, and tertiary alcohols has been achieved via SN 1-type reactions with catalytic amounts of Brønsted or Lewis acids. When a new stereogenic center is formed most of these transformations produce the desired product as a racemate, as these reactions proceed through carbenium ions. The arsenal of activation modes available in organocatalysis can be used to set up suitable reaction conditions in which chiral nucleophiles (enamine catalysis) or chiral electrophiles (iminium catalysis, chiral counterion catalysis) can easily be generated. Recently, we have used stabilized carbenium ions, directly available or obtained from the corresponding alcohols, in new organocatalytic stereoselective SN 1-type reactions. The commercially available carbenium ion benzodithiolylium tetrafluoroborate can be used for the straightforward organocatalytic stereoselective alkylation of aldehydes. In this account we will illustrate the application of this methodology in the total synthesis of natural products and the preparation of valuable starting materials.

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“…In particular, we are interested in controlling the introduction of many methyl groups, with the correct absolute configuration and relative configuration in the 1,3‐, 1,4‐, and 1,5‐positions on an alkyl chain, by a reproducible and iterative process 111. From the preliminary results obtained, the problems related to matched or mismatched stereoselective reactions, that are encountered, for example, in the Michael organometallic approach,112 seem to be absent in this methodology. In addition, these findings can be applied towards a synthesis of biologically active products, such as Baulamycin A and B 113.…”

Section: An Unexpected Journey: Carbenium Ions For Organocatalytic Snmentioning

confidence: 99%

From QCA (Quantum Cellular Automata) to Organocatalytic Reactions with Stabilized Carbenium Ions

Gualandi

Mengozzi

Manoni

et al. 2016

The Chemical Record

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What do quantum cellular automata (QCA), "on water" reactions, and SN 1-type organocatalytic transformations have in common? The link between these distant arguments is the practical access to useful intermediates and key products through the use of stabilized carbenium ions. Over 10 years, starting with a carbenium ion bearing a ferrocenyl group, to the 1,3-benzodithiolylium carbenium ion, our group has exploited the use of these intermediates in useful and practical synthetic transformations. In particular, we have applied the use of carbenium ions to stereoselective organocatalytic alkylation reactions, showing a possible solution for the "holy grail of organocatalysis". Examples of the use of these quite stabilized intermediates are now also considered in organometallic chemistry. On the other hand, the stable carbenium ions are also applied to tailored molecules adapted to quantum cellular automata, a new possible paradigm for computation. Carbenium ions are not a problem, they can be a/the solution!

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Asymmetric synthesis of cyclo-archaeol and β-glucosyl cyclo-archaeol

Cited by 17 publications

References 54 publications

Synthesis and Analysis of the All-(S) Side Chain of Phosphomycoketides: A Test of NMR Predictions for Saturated Oligoisoprenoid Stereoisomers

Synthesis and Analysis of the All-(S) Side Chain of Phosphomycoketides: A Test of NMR Predictions for Saturated Oligoisoprenoid Stereoisomers

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

From QCA (Quantum Cellular Automata) to Organocatalytic Reactions with Stabilized Carbenium Ions

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