A general route to the synthesis of 3-alkylidene derivatives of 4-thiochromanone 1,1-dioxide

1984 ◽  
Vol 62 (11) ◽  
pp. 2535-2539
Author(s):  
Ian W. J. Still ◽  
Fred J. Ablenas
Keyword(s):  
Carbonyl Compounds ◽  
Lewis Acids ◽  
Boron Trifluoride ◽  
Titanium Tetrachloride ◽  
Enol Ethers ◽  
Mild Conditions ◽  
Condensation Products ◽  
Derivatives Of

The reactions of the trimethylsilyl enol ethers of both 4-thiochromanone and 4-thiochromanone 1,1-dioxide with various carbonyl compounds complexed with titanium tetrachloride give moderate yields of the previously unknown 3-alkylidene condensation products under mild conditions. Other Lewis acids, with the exception of boron trifluoride, were found to be ineffective in this transformation.

scholarly journals 2-Iodoxybenzoic Acid: An Oxidant for Functional Group Transformations: (A-Review)

2020 ◽  
Vol 36 (05) ◽  
pp. 792-803
Author(s):  
Vipin A. Nair
Keyword(s):  
Carbonyl Compounds ◽  
Room Temperature ◽  
Water Soluble ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Carbon Carbon Bond ◽  
Oxidation Of Alcohols ◽  
Major Application ◽  
Almost All ◽  
Derivatives Of

A major application of 2-Iodoxybenzoic acid (IBX) is the oxidation of alcohols to carbonyl compounds, at room temperature. IBX is insoluble in almost all solvents, except DMSO. IBX tolerates amine functionality and is therefore used for the oxidation of amino alcohols to amino carbonyl compounds. IBX oxidizes 1,2-glycols without the cleavage of the glycol carbon-carbon bond. Allylic and benzylic positions are also susceptible to oxidation by IBX. Synthesis of a,b-unsaturated carbonyl compounds from carbonyl compounds can be accomplished by using IBX as oxidant. Silyl enol ethers undergo oxidation upon exposure to IBX and 4-methoxypyridine N-oxide. Water-soluble derivatives of IBX, and polymer-based IBX, with additional advantages, have also been developed. IBX mediated transformations facilitate the construction of diverse heterocyclic systems.

α-Alkoxyalkyl Triphenylphosphonium Salts: Synthesis and Reactions

2019 ◽  
Vol 23 (16) ◽  
pp. 1738-1755
Author(s):  
Humaira Y. Gondal ◽  
Zain M. Cheema ◽  
Abdul R. Raza ◽  
Ahmed Abbaskhan ◽  
M. I. Chaudhary
Keyword(s):  
Carbonyl Compounds ◽  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Coupling Reactions ◽  
Phosphonium Salts ◽  
Organic Transformations ◽  
Enol Ethers ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Alkoxy Groups

Following numerous applications of Wittig reaction now functionalized phosphonium salts are gaining attention due to their characteristic properties and diverse reactivity. This review is focused on α-alkoxyalkyl triphenylphosphonium salts: an important class of functionalized phosphonium salts. Alkoxymethyltriphenylphosphonium salts are majorly employed in the carbon homologation of carbonyl compounds and preparation of enol ethers. Their methylene insertion strategy is extensively demonstrated in the total synthesis of a wide range of natural products and other important organic molecules. Similarly enol ethers prepared thereof are important precursors for different organic transformations like Diels-Alder reaction, Claisen rearrangement, Coupling reactions, Olefin metathesis and Nazarov cyclization. Reactivity of these α-alkoxyalkylphosphonium salts have also been studied in the nucleophilic substitution reactions. A distinctive application of this class of phosphonium salts was recently reported in the phenylation of carbonyl compounds under very mild conditions. Synthesis of structurally diverse alkoxymethyltriphenylphosphonium salts with variation in alkoxy groups as well as counter anions are reported in literature. Here we present a detailed account of different synthetic methodologies for the preparation of this unique class of quaternary phosphonium salts and their applications in organic synthesis.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Low-Temperature Syntheses of Thioketals from Enol Ethers and Carbonyl Compounds.

ChemInform ◽  
2003 ◽  
Vol 34 (19) ◽  
Author(s):  
Arnaud Martel ◽  
Sopa Chewchanwuttiwong ◽  
Gilles Dujardin ◽  
Eric Brown
Keyword(s):  
Low Temperature ◽  
Carbonyl Compounds ◽  
Enol Ethers
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