Polymergebundenes Sulfonylazid zur entformylierenden Diazogruppen-Übertragung und zur Diazo -cyclopolyen -Synthese / Polymer Anchored Sulfonylazide for Deformylating Diazo Group Transfer and the Synthesis of Diazo-cyclopolyenes

Hauck, Gerd; Brück, Wolfgang; Kober, Helge

doi:10.1515/znb-1981-0918

Cited by 7 publications

(1 citation statement)

References 3 publications

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“…We also examined the use of a supported diazo-transfer reagent to facilitate reaction workup and purification. , However, sulfonyl azide resin prepared from 20% cross-linked polystyrene following a reported method failed to effect diazo-transfer to the trifluoroacylated lactone 29a or even to ethyl acetoacetate in our hands . Fortunately sulfonyl azide resin prepared from commercial polystyrenesulfonyl chloride (Argonaut, 1% cross-linked) did function as a diazo-transfer reagent to afford 30 from 29a in 64% yield, although relatively large amounts of the expensive resin were required and reaction was significantly slower than its homogeneous counterpart.…”

Section: Resultsmentioning

confidence: 98%

C−H Insertion Approach to the Synthesis of endo,exo-Furofuranones: Synthesis of (±)-Asarinin, (±)-Epimagnolin A, and (±)-Fargesin

et al. 2001

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A series of novel 5-aryl-4-aryloxymethyl-3-diazotetrahydrofuran-2-ones (12, 24, and 35a/b) have been prepared and found to undergo regio- and stereoselective C-H insertion reactions to afford 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-8-ones (18, 26, and 36a/b) with endo,exo stereochemistry. Subsequent reduction of the lactone ring and cyclization of the resulting diols 27 and 37a/b permitted the synthesis of three endo,exo-furofuran lignans: asarinin (2), fargesin (3), and epimagnolin A (4). En route to the key diazo compounds 24 and 35a/b, a modified procedure for the Ghosez keteniminium-olefin cyclization was developed, which was required to minimize the decomposition of acid-sensitive functional groups such as electron-rich benzylic ethers that were present in the target compounds 2-4.

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Section: Resultsmentioning

confidence: 98%

C−H Insertion Approach to the Synthesis of endo,exo-Furofuranones: Synthesis of (±)-Asarinin, (±)-Epimagnolin A, and (±)-Fargesin

et al. 2001

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Electrophilic Amination of Carbanions, Enolates, and Their Surrogates

Ciganek

2009

Organic Reactions

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This chapter deals with the formation of carbon‐nitrogen bonds by reaction of carbon nucleophiles with electrophilic aminating reagents. The former encompass aliphatic and aromatic carbanions, enolates and their surrogates such as enamines, enol esters, and enol ethers, as well as carbanions stabilized by cyano or sulfone groups or by phosphorus. A section entitled Reagents and Mechanisms lists the many aminating reagents available and discusses the mechanisms by which the more important ones react. Among the electrophiles discussed are halo amines, various hydroxylamine derivatives, oxaziridines, imines, oximes, diazonium salts, diazo compounds, azo compounds, and azides. The section on Scope and Limitations is organized by carbon nucleophiles and attempts to suggest the best reagents for each class. A number of electrophilic aminating reagents that have been omitted from the scope of this chapter are briefly discussed, with references to reviews, in the section on Comparison with Other Methods. Tables listing references to the preparation of the various aminating reagents are found in the section on Experimental Conditions. References to the conversion of non‐amine products into amines are also provided there. The literature is covered to the middle of 2007.

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Carben‐Umlagerungen, XX. trans ‐2‐(1,3‐Butadienyl)cyclopropyliden: Erzeugung und Umlagerungsverhalten

Brinker

Fleischhauer

1986

Chem. Ber.

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20) and trans-l,2,4,6-heptatetraene (21) are formed from truns-2-(1,3-butadienyl)cyclopropylidene(oid) (l8), which is generated from the dibromocarbene adduct 17 with methyllithium at 0°C. The mechanisms of the rearrangements of 18 have been examined by '2C-labeling ('2C> 99.95%) in 17. 21 is formed from 18 by rupture of the distal bond B of the cyclopropylidene. Breakage of the lateral bond A in 18 induces a carbenecarbene rearrangement with 1,3-C migration. The rearranged carbene 28 stabilizes itself by three routes. The product ratio of the competing reactions in 18 is temperature dependent. At lower temperatures the carbene-carbene rearrangement 18 -+ 20 predominates, at higher temperatures increased formation of 21 takes place. -If 18 is generated by pyrolysis of the organotin compound 34, the high temperature (260 "C) necessary for the decomposition favors the allene formation and suppresses the carbene-carbene rearrangement. -21 is also formed when 18 is released from the N-nitrosourea 36b. 19 and 20 decompose under the reaction conditions. -A new method for the generation of carben(oid)s is described.

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Polymergebundenes Sulfonylazid zur entformylierenden Diazogruppen-Übertragung und zur Diazo -cyclopolyen -Synthese / Polymer Anchored Sulfonylazide for Deformylating Diazo Group Transfer and the Synthesis of Diazo-cyclopolyenes

Cited by 7 publications

References 3 publications

C−H Insertion Approach to the Synthesis of endo,exo-Furofuranones: Synthesis of (±)-Asarinin, (±)-Epimagnolin A, and (±)-Fargesin

C−H Insertion Approach to the Synthesis of endo,exo-Furofuranones: Synthesis of (±)-Asarinin, (±)-Epimagnolin A, and (±)-Fargesin

Electrophilic Amination of Carbanions, Enolates, and Their Surrogates

Carben‐Umlagerungen, XX. trans ‐2‐(1,3‐Butadienyl)cyclopropyliden: Erzeugung und Umlagerungsverhalten

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