Reaktionen mit Phosphinalkylenen, XVII. Eine neue Synthese von γ‐Ketosäuren und β‐Acyl‐acrylsäureestern

Bestmann, H. J.; Graf, Gerhard; Hartung, H.

doi:10.1002/jlac.19677060107

Cited by 26 publications

(6 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although p-quinone diimines 7, 8 have been reported [lo-121 to react with Wittig reagents to give (1 : 1) adducts 9, 10, a different behavior is observed in the reaction of quinone monoimines 2 with the same reagent (Scheme 6)…”

Section: Discussionmentioning

confidence: 93%

“…Treatment of the ylide-phosphorane adduct 4a with benzoic acid brought about an elimination reaction [8] that resulted in the formation of the trans and cis isomeric compounds 5a and 5b, respectively [9] (Scheme 4). Melting points and 'H NMR and mass spectroscopic data of 5a and 5b are given (cf.…”

Section: Resultsmentioning

confidence: 99%

“…To a suspension of 4a (0.2 g) in tetrahydrofuran (30 mL) was added benzoic acid (0.24 g, 0.002 mol), and the reaction mixture was refluxed for 8 hours. The volatile materials were removed under reduced pressure, and the residual substance was applied to silica gel column chromatography using ethyl acetate/petroleum ether as eluent.…”

Section: Action Of Benzoic Acid On 4amentioning

confidence: 99%

See 2 more Smart Citations

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

Boulos

Hennawy

Arsanious

1994

Heteroatom Chemistry

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Action Of Benzoic Acid On 4amentioning

confidence: 99%

See 1 more Smart Citation

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

Boulos

Hennawy

Arsanious

1994

Heteroatom Chemistry

View full text Add to dashboard Cite

show abstract

“…'l succeeded in isolating 13-deoxo-1 l-deoxydaunorubicin ( I ) and 1 1 -deoxydaunorubicin (2). which proved to have particularly useful antitumor effects in animals.…”

mentioning

confidence: 99%

“…We describe here, a variable synthetic method for this class of compounds starting from primary alkyl halides, carboxylic acids and aldehydes.Alkylidenetriphenylphosphoranes ( I ) , whose ylide substructure is formed from a primary alkyl halide o r alcohol, can be transformed by treatment with the carboxylic acid derivatives (2) to acyl ylides (3)I'l. The ambidentateL2] phosphoranes (3) are O-alkylated[31, by treatment with ethyl bromide, to the phosphonium salts (4).…”

mentioning

confidence: 99%

A Novel Route to 2‐Ethoxybutadienes; Diels‐Alder Reaction of 1,2‐λ⁵‐Oxaphosphorines

Bestmann

Roth

1981

Angew. Chem. Int. Ed. Engl.

Self Cite

View full text Add to dashboard Cite

Dedicated to Professor Siegfried Hiinig on the occasion of his 60th birthday 2-Ethoxybutadienes are, as enol ethers of a$-unsaturated carbonyl compounds, versatile and useful synthons. We describe here, a variable synthetic method for this class of compounds starting from primary alkyl halides, carboxylic acids and aldehydes.Alkylidenetriphenylphosphoranes ( I ) , whose ylide substructure is formed from a primary alkyl halide o r alcohol, can be transformed by treatment with the carboxylic acid derivatives (2) to acyl ylides (3)I'l. The ambidentateL2] phosphoranes (3) are O-alkylated[31, by treatment with ethyl bromide, to the phosphonium salts (4). from which a yproton can be abstracted by sodium amidel"]. The 2-cupies the apical position[81. In the 3'P-NMR spectra, particularly that of (9) (R2 =! = H), two broad signals appear at 6= + 10 to + 16 and -20 to -50 (H3P04 as external standard); these indicate an equilibrium between (9) and (12). In polar solvents such as CDCI,, this lies more on the side of (9), while in nonpolar solvents, such as benzene and toluene, (12) is more predominant. If solutions of (9)/(12) R' = H in toluene are treated with N-methylmaleimide (13), the substituted N-methylphthalimides ( I 7 ) [ ' I and triphenylphosphane oxide (15) can be isolated whose formation we account for by the following mechanism: (12). in a Diels-Alder reaction with (13), yields the bicycle (14). After Iigand rearrangement to (14'), the bridgehead C-atom bonded to the phosphorus occupies a n apical position in the trigona! bipyramid, permitting cleavage of the C-P bondfg1, which is cleaved in a cycloreversion to (IS). The dihydrophthalimide derivative (16) is formed, which is dehydrated in the work-up to (17). In principle, a cycloaddi6Et ethoxyallylidenetriphenylphosphoranes, which are described in the mesomeric limiting structures (5) and (5') are thus formed, and formally react as (5') with aldehydes (8) in a Wittig reaction to the 2-ethoxybutadienes (10) ( Table 1); as en01 ethers they are readily converted into a,b-unsaturated ketones by known methods. On the other hand, the ylides (5) react with acid chlorides (6) at the y-position to the P atom[51. Thus, apart from 1 mole of the phosphonium salt (C1' instead of Br'), the acylphosphoranes (9) are formed from (5) and (6) (2 : 1 molar ratio). lsocyanates ( 7 ) also attack the ally1 ylides (5) at the y-position to form, after proton rearrangement, the carbamoyl-substituted compounds (9)16]. Wittig reaction of (9) with (8) produces the 1-acyl-2-ethoxybutadienes (11) (Table l), from which, inter alia, y,&unsaturated 1,3-dicarbonyl compounds and derivatives of the 2,3-dihydro-4-pyrones can be obtained"'.(9). which is describable via mesomeric limiting structures, should exist in several different conformations. It therefore follows, in particular when R2 =/= H, that reaction of (8) with (9) should lead to formation of compound (11) having a mixture of Z. E-isomers at the I-position. In contrast, carbonyl olefination forms a new double bond having E-geometry whi...

show abstract

C,P‐Carbon‐Substituted Phosphorus Ylides

Kolodiazhnyi

1999

Phosphorus Ylides

View full text Add to dashboard Cite

Reaktionen mit Phosphinalkylenen, XVII. Eine neue Synthese von γ‐Ketosäuren und β‐Acyl‐acrylsäureestern

Cited by 26 publications

References 15 publications

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

A Novel Route to 2‐Ethoxybutadienes; Diels‐Alder Reaction of 1,2‐λ⁵‐Oxaphosphorines

C,P‐Carbon‐Substituted Phosphorus Ylides

Contact Info

Product

Resources

About

Reaktionen mit Phosphinalkylenen, XVII. Eine neue Synthese von γ‐Ketosäuren und β‐Acyl‐acrylsäureestern

Cited by 26 publications

References 15 publications

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

Studies on phosphonium ylides XX. The behavior of Wittig reagents toward 1,4‐benzoquinone monoimines

A Novel Route to 2‐Ethoxybutadienes; Diels‐Alder Reaction of 1,2‐λ5‐Oxaphosphorines

C,P‐Carbon‐Substituted Phosphorus Ylides

Contact Info

Product

Resources

About

A Novel Route to 2‐Ethoxybutadienes; Diels‐Alder Reaction of 1,2‐λ⁵‐Oxaphosphorines