Phosphabarrelenes as Ligands in Rhodium‐Catalyzed Hydroformylation of Internal Alkenes Essentially Free of Alkene Isomerization

Fuchs, Evelyn; Keller, Manfred; Breit, Bernhard

doi:10.1002/chem.200600180

Cited by 73 publications

(32 citation statements)

References 34 publications

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“…The diolw as cleaved with sodium periodate and olefination reactions conducted on the resulting aldehyde with av iew to producing various unsaturateds ide chains. Attempts to attach the E-propenyl side chain presentint he naturalp roduct by Julia-Kocienski reaction (ethyl 1-phenyl-1H-tetrazol-5-yl sulfone, [19 ] KHMDS or LiHMDS, THF) were unsuccessful, leading to degradation that prevented isolation of any product or startingm aterial. Similard egradation wasa lso observed in aW ittig reaction with the ylide derived from ethyltriphenylphosphonium iodide.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Bioactive Side‐Chain Analogues of TAN‐2483B

Somarathne

McCone

Brackovic

et al. 2019

Chemistry An Asian Journal

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The fungal metabolite TAN‐2483B has a 2,6‐trans‐relationship across the pyran ring of its furo[3,4‐b]pyran‐5‐one core, which has thwarted previous attempts at its synthesis. We have now developed a chiral pool approach to this core and prepared side‐chain analogues of TAN‐2483B. The synthesis relies on ring expansion of a reactive furan ring‐fused dibromocyclopropane and alkynylation of the resulting pyran. The furan ring is constructed by palladium‐catalysed carbonylative lactonisation. Various side‐chains are appended through Wittig‐type chemistry. The prepared analogues showed micromolar activity towards cancer cell lines HL‐60, 1A9 and MCF‐7 and certain human disease‐relevant kinases, including Bruton's tyrosine kinase (Btk).

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Section: Resultsmentioning

confidence: 99%

Synthesis of Bioactive Side‐Chain Analogues of TAN‐2483B

Somarathne

McCone

Brackovic

et al. 2019

Chemistry An Asian Journal

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“…The reaction mixture was stirred at this temperature for 1 h followed by addition of a solution of tetrazole10 21 (164.8 mg, 0.8 mmol) in THF (2 ml). The reaction mixture was further stirred at −30 °C for 3 h and then quenched by the addition of saturated NH 4 Cl solution.…”

Section: Methodsmentioning

confidence: 99%

Sulfanylation of 1,3-dithiane anions by 5-(alkylsulfanyl)-1-phenyltetrazoles

Gudipati¹,

Bajpai²,

Curran³

2009

Collect. Czech. Chem. Commun.

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An unusual reaction between 1,3-dithiane anions and by 5-(alkylsulfanyl)-1-phenyltetrazoles has been discovered in which the dithiane anion formally displaces the 1-phenyltetrazole ring from sulfur to provide a sulfanylated dithiane. KeywordsTetrafibricin; Total synthesis; 1,3-Dithianes; 5-(Alkylsulfanyl)-1-phenyltetrazoles; Nucleophilic additions; Sulfanylations; Sulfur chemistryThe natural product tetrafibricin 1 was isolated in 1993 by Kamayama and coworkers, and they assigned its two-dimensional constitution by a battery of spectroscopic methods 1 . The compound has a linear carbon backbone featuring 11 stereocenters (10 with hydroxy groups and one with a methyl group), is a tetraene, with three isolated trans double bonds, and assorted other functional groups. In 2003, Kishi and coworkers assigned the threedimensional structure (configuration) of 1 without resorting to derivatization or degradation by comparing NMR spectra of the natural product in both chiral and achiral solvents to an NMR database of fragment spectra 2 . Roush 3 and Cossy 4 have described syntheses of fragments of 1.We have advanced a retrosynthetic strategy in Fig. 1 of the disassembled tetrafibricin 1 into six main fragments 2-7. Though the synthesis has not yet been completed, all of the fragments have been made, and assorted couplings have been established 5 . Along the way to making the C21-C30 fragment 4, we encountered an unusual reaction between a dithiane anion 6 and a 5-(alkylsulfanyl)-1-phenyltetrazoles. Herein we describe this reaction, which, in the context of the tetrafibricin synthesis, proved to be a temporary roadblock. We also describe a straightforward detour around this roadblock to complete the synthesis of a modified C21-C30 fragment. RESULTS AND DISCUSSIONThe two fragments 13 and 17 needed to make 4 were synthesized as shown in Scheme 1. Oxidation 7 of commercially available dioxolane alcohol (S)-8 to aldehyde 9 was followed by the Wittig reaction and non-selective epoxidation of the resulting alkene 10 to give a

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“…We therefore sought to investigate the relative r-bonding properties of the structurally related 2,4,6-tritertiarybutylphosphabenzene, PC 5 Bu t 3 2 and 1, in view of current interest in the catalytic potential of these types of sp 2 -hybridised phosphoruscontaining rings and related phosphabarrelenes [6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%