Horner synthesis

Diethyl [(2-tetrahydropyranyloxy)methyl]phosphonate is useful in the Wlttig-Horner synthesis of enol ethers, which are intermediates in one-carbon homologations of carbonyl compounds. This procedure is an adaptation of a general method for making dialkyl hydroxymethylphosphonates. An 0-tetra-hydropyranyl derivative also has been made from dibutyl hydroxymethyl -phosphonate, and diethyl hydroxymethylphosphonate has been O-silylated with tert-butylchiorodimethylsilane and imidazole. Another useful congener in this series has been prepared by an Arbuzov reaction of methoxyethoxymethyl (HEM) chloride and triethyl phosphite. 

Fig. 11.10. Wittig-Horner synthesis of alkenes with stereogenic C=C double bond via condensation of lithiated phosphine oxides B <-> B with aldehydes. In the two-step reaction the initially formed addition products syn- and anti-D are protonated and the resulting alcohols syn- and anti-C are isolated and separated the suitable diastere-omer is then stereoselectively converted into the desired alkene isomer. The one-step reaction leads to the same alkene in a cis,trans mixture.

Fig. 11.11. Wittig-Horner synthesis of stereouniform alkenes via ketophosphine oxide B. The reaction proceeds via its Felkin-Anh-selective or chelate-controlled reduction to form the syn-configured hydroxyphosphine oxides D and the anti-configured hydroxyphosphine oxides E. D and E continue to react—after deprotonation with KO-tert-Bu—via a syn-elimination to give the trans- and cis-alkene, respectively. R1 in the formula A-C corresponds to a primary (prim-alkyl) or a secondary alkyl residue (sec-altyl).

Grison, Ph. C. C. and Sauvetre, R. (1987) 2-Diethoxyphosphoryl alkanoic acid dianions IV. A direct route to 2-fluoro-2-alkenoic acids by the Horner synthesis. Application in the field of pyrethroids. J. Organomet. Chem., 332, 1-8. 

Allylic phosphine oxides Witrtg-Horner synthesis of 1,3-dienes AUylic phosphine oxides can be prepared by reaction of 2,6-dichlorobenzoates of allylic alcohols with lithium diphenylphosphide followed by oxidation. Thus... 

Diethyl [(2-tetrahydropyranyloxy)raethylIphosphonate is useful in the Wittig-Horner synthesis of enol ethers, which are intermediates in one-carbon... 

An electrolytically generated base, hydrazobenzene from azobenzene, has been used for a Wittig synthesis. This method permits the maintenance of any desired base concentration by controlling the current Certain ketones can be conveniently obtained through a Horner synthesis of thioenolethers... 

Horner synthesis with nitroso compounds Amidines... 

Sodium hydroxide tetrabutylammonium iodide Phase-transfer-catalyzed Horner synthesis... 

Diisopropyl chloromethylphosphonate allowed to react at -78° with n-butyl-lithium in tetrahydrofuran, then with CCI4 at the same temp. diisopropyl dichloromethylphosphonate. Y 90-95%. F. e., chlorinating agent, and limitation s. P. Savignac, M. Dreux, and P. Coutrot, Tetrah. Let. 1975, 609 also a,) -ethylene-cfalorides by subsequent Horner synthesis s. Synthesis 1975, 658. 

Startg. aldehyde reacted with 2 eqs. ethyl triphenylphosphoranylideneacetate in THF for 1 h intermediate thioenolether (Y 87% E Z 1 3), hydrolysed with trifluoroacetic acid-water (4 l)/methylene chloride at 20° for 3 h product (Y 94%). KOBu-r may be used to isomerize the initially-formed double bond. F.e. inch y-keto-nitriles and -amides, y-diketones, and 1,4,7-tricarbonyl compds., also via Horner synthesis, s. T. Sato et al., J. Am. Chem. Soc. 110, 5209-11 (1988). 

Horner synthesis with -, review of effect of lithium coordination 39, 854s43... 

Sodium amide Horner synthesis Ethylene derivatives... 

Horner synthesis with migration of the carbon-carbon double bond into rings... 

J,19-cyclosteroids 19, 814 Horner synthesis 14, 877 Huang Minion reduction s. Wolff-Kishner Hydantoin dyes 19, 309 Hydantoins... 

A suspension of NaH in abs. tetrahydrofuran stirred and treated portionwise at 0° with diethyl methoxycarbonylmethylphosphonate, after completion of the Hg-evolution a soln. of cortexone in abs. tetrahydrofuran added whereupon the temp, rises to 40-50° then drops to ca. 30°, the product isolated after 35 min. stirring crude butenolide. Y 90.1%. F. e. s. W. Fritsch, U. Stache, and H. Ruschig, A. 699, 195 (1966) a, -ethylenecarboxyiic acid esters from ketones, labeled compounds, s. W. M. Walter, Jr., J. Labelled Compds. 3, 54 (1967) a,/ -ethylenephosphonic from methylenediphosphonic acid esters s. T. L. Hular, Tetrah. Let. 1967, 4921 a,y -ethylenealdehydes from oxo compounds by Horner synthesis cf. W. Nagata and Y. Hayase, Tetrah. Let. 1968, 4359. 

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