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Horner-Wittig reagents

Aldehydes.1 This Wittig-Horner reagent (available from Fluka) converts aldehydes or ketones into a,fi-unsaturated isocyanides, which can be hydrolyzed to the one-carbon homologated aldehyde. [Pg.135]

In a synthesis of the natural insecticide ajugarin-IV (4),4 the butenolide portion was prepared from the acid chloride 3 in two steps. Reaction with tris(lrimethylsilyloxy)ethylene (8, 523 9, 512)5 led to a hydroxymethyl ketone, which on reaction with 1 was converted into the butenolide 4. In this series, 1 was vastly Kupcrior to the alternative Wittig-Horner reagent 2. [Pg.483]

A mechanism, via a 6-hydroxy phosphorothiolate 8-mercapto-phosphate rearrangement, will be shown, and these new synthons will be compared with the phosphonate analogs (Wittig -Horner reagent). [Pg.151]

This Wittig-Horner reagent is prepared chloroacetyl chloride and N(C2H5)3 in CHj phosphite. The anion (BuLi) of 1 reacts wbi amates, which are reduced to aldehydes by... [Pg.206]

Dicarbonyl compounds. The adducts (2) of the anion (1) of meth-oxy(phenylthio)methane and aldehydes (12, 316) are converted into a-sulfenyl aldehydes (3) on treatment with methanesulfonyl chloride and triethylamine (1 1). Reaction of 3 with a Wittig or Wittig-Horner reagent followed by isomerization... [Pg.202]

J. Seyden-Penne, Lithium coordination by Wittig-Horner reagents formed by a-carbonyl substituted phosphonates and phosphine oxide, Bull. Soc. Chim. Fr. 1988, 238. [Pg.372]

WITTIG-HORNER REAGENTS Carbome-thoxyethyl(diphenyl)phosphine oxide. Die-thoxymethyldiphenyl phosphine oxide. Diethyl [(2-tetrahydropyranyloxy)-methyl -phosphonate. Methyl bis(trifluoroethyl)-phosphonoacetate. N-Morpholinodiphenyl-phosphine oxide. Triethylphosphonoace-tate. [Pg.669]

I). The phosphonate is obtained by lithiation of the corresponding Wittig-Horner reagent. ... [Pg.387]

WITTIG-HORNER REAGENTS Diethyl 2,2-dichloro-l-ethoxyvinyl phosphate. Diethyl methoxyefhoxymethylphos-phonate. Dimethyl 3-bromo-2-ethoxy-propenylphosphonate. Methoxymethyl-(diphenyl)phosphine oxide. [Pg.575]

The 1,3-dichalcogenolylium cations are used in the formation of Wittig or Wittig-Horner reagents, see Scheme 16. [Pg.687]

A direct and, in some cases, more effective method to a mixed system yielding a single fulvalene derivative, is based on reaction of a l,3-dichalcogenole-2-iiimionium salt (97) with an appropriate Wittig-Horner reagent (96) as Scheme 20 demonstrates <89MI 314-01>. [Pg.694]

WITTIG-HORNER REAGENTS Cyano-methyldiphenylphosphine xide. Diethyl carboxymethanephosphonate. Diethyl trimethylsilyloxycarbonyl-methanephosphonate. [Pg.584]

Compound 11 is, however, unexpectedly unreactive with Wittig-Horner reagents. Upon heating with the carbanion of ester phosphonates an addition across the allenic bond occurs [14]. In contrast, a slow normal 1,2-addition takes place [14] with the ylide from cyano-methylphosphonate but, unexpectedly, this proceeds with concomitant inversion at the chiral axis as shown in Scheme 3, to give a mixture of 6R or 6S, and (9E)- or (9Z)-isomers 12-15. However, a fast and very clean 1,2-addition occurs with the ethynyl ketone 18 to yield the esters 19 and 20 (Scheme 4). DIB AH reduction of the separated stereoisomers gives the allenic alcohols 21 and 22 in high yield. Mild oxidation to the aldehydes 23 and 24, followed by their condensation with the acetylenic Cio-bis-ylide 25, leads to the stereoisomeric 15,15 -didehydromimulaxanthins 26 and 28, respectively (Schemes 5 and 6). The optically active. [Pg.204]

The reactivity of phospha-Wittig-Horner reagents towards ketenes has been adopted as a route to 1-phosphaallenes (Scheme 181). ... [Pg.587]

A remarkable, synthetic pathway for conversion of readily available phospha-Wittig-Horner reagent (355) into highly functionalised phos-pholes (356) and 1,2-oxaphospholes (357) has been described by Ott and co-workers (Scheme 121). [Pg.301]


See other pages where Horner-Wittig reagents is mentioned: [Pg.17]    [Pg.263]    [Pg.267]    [Pg.328]    [Pg.653]    [Pg.340]    [Pg.383]    [Pg.229]    [Pg.74]    [Pg.340]    [Pg.90]    [Pg.376]    [Pg.207]    [Pg.187]    [Pg.307]    [Pg.33]    [Pg.104]   
See also in sourсe #XX -- [ Pg.135 ]

See also in sourсe #XX -- [ Pg.206 , Pg.383 ]




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