Allylic propenyl derivatives

Allyl alcohol has been produced by the selective reduction of acrolein and the isomerization of propylene oxide. However, most allylic derivatives are produced via allyl chloride, obtained by the chlorination or oxychlorination of propylene. 

A more significant use of allyl chloride is for the production of epi-chlorohydrin (3-chloro-l, 2-epoxypropane), an important precursor for epoxy-resins. 

---

Finally, 2-allyl-4,5-tra ,s-diphenyl-l,3-bis(4-methylphenylsulfonyl)-l,3,2-diazaborolidincs have been used74. The 2-propenyl derivative undergoes highly stereoselective reactions with achiral aldehydes (95 - 97% ee) the ( )-2-butenyl derivatives (91-95% ee) and the analogous 2-chloro- and 2-bromo-2-propenyl derivatives (84-99% ee) also give excellent results in reactions with achiral aldehydes. 

The synthesis of (S)-ibuprofen (S)-34 utilizing allylic alkylation was undertaken to determine the stereochemical course of this process. The reaction of the enantiomeri-cally enriched allylic carbonate (S)-32 (95% ee) with the requisite aryl zinc bromide (Scheme 10.7) [32], under optimized reaction conditions, furnished the 3-aryl propenyl derivative (R)-33 in 90% yield (2° 1°=10 1) with inversion of configuration (100% cee). The synthesis of (S)-ibuprofen (S)-34 was then completed through the oxidative cleavage of the aUcene (R)-33 in 74% yield [33]. 

A-Allyl compounds can be rearranged to A-propenyl derivatives. Similarly, A-propargyl compounds (969) give A-allenyl derivatives (970). 

There are few reports of the transition metal complex-catalyzed isomerization of S-allyl sulfides and sulfones. This is clearly a consequence of the very strong coordinating ability of sulfur atoms and the resulting tendency for S-C (allyl) bond cleavage. In the case of a bulky substituent being present at the sulfur atom, the isomerization to 1-propenyl derivatives is successful (Eqs. 12.14 and 12.15) [20]. 

Isomerization of the C-allyl glycoside 302 provides the corresponding C-(l-propenyl) derivative 303 as a major E-isomer. Cross metathesis proceeds in high yield only with the Grubbs II catalyst to deliver the homodimer 304, transformed to C-disaccharide analog 305 of the mycobacterial motif. 

The 8-allyl derivative of 56 can be rearranged to the respective propenyl derivative of 57 by the action of sodium ethoxide (93KGS1545) (Scheme 17). 

There is no reactivity problem w acceptors. (Tin can be used instead of Many functionalized allylic halid straightforward syntheses of useful t iodide, 2-bromomethyl-2-propenyl derivative from 2-bromomethylacryli including A7-acetylneuraminic acid. Of... 

An equimolar amount of XiCl4 added dropwise by syringe under Ng to a soln. of Jl,9-2-octalone in methylene chloride, stirred 5 min., 1.4 molar equivalents allyl-trimethylsilane in methylene chloride added dropwise at -78°, stirred 18 hrs. at -78° and 5 hrs. at -30°, then treated with water -> y -allylated ketone (Y 85%) refluxed with dichlorobis(benzonitrile)palladium(II) in benzene -> propenyl deriv. (Y 93%). F. 5, -ethyleneketones s. A. Hosomi and H. Sakurai, Am. Soc. 99, 1673 (1977) f. reactions with 2-ethylenesilanes s. B.-W. Au-Yeung and I. Fleming, Chem. Commun. 1977, 79, 81. 

Freparatively useful induced diastereoselectivities have been reported mainly for 1,1-di-substituted allyllithium derivatives which bear carbanion-stabilizing substituents. l-[Methyl-thio-l-(trimethylsilyl)-2-propenyl]lithium106 and the appropriate 1-phenylthio107 derivative, generated from the allylic sulfide with sec-butyllithium, in the reaction with tetrahydropyranyl-protected pregnolone, furnish a single diastereomer. 

Two approaches for the synthesis of allyl(alkyl)- and allyl(aryl)tin halides are thermolysis of halo(alkyl)tin ethers derived from tertiary homoallylic alcohols, and transmetalation of other allylstannanes. For example, dibutyl(-2-propenyl)tin chloride has been prepared by healing dibutyl(di-2-propenyl)stannane with dibutyltin dichloride42, and by thermolysis of mixtures of 2,3-dimethyl-5-hexen-3-ol or 2-methyl-4-penten-2-ol and tetrabutyl-l,3-dichlorodistannox-ane39. Alternatively dibutyltin dichloride and (dibutyl)(dimethoxy)tin were mixed to provide (dibutyl)(methoxy)tin chloride which was heated with 2,2,3-trimethyl-5-hexen-3-ol40. 

Nucleophilic addition to a, -unsaturated sulfones has long been known. For example, treatment of divinyl sulfone with sodium hydroxide has been known to afford bis( -hydroxyethyl) sulfone "", while the reaction of a- and -naphthyl allyl sulfones and allyl benzyl sulfone " with alkali hydroxide or alkoxide gave -hydroxy or alkoxy derivatives. In the latter reaction, the allyl group underwent prototropy to the 1-propenyl group, which in a subsequent step underwent nucleophilic attack . Amines, alcohols and sulfides are known to add readily to a, -unsaturated sulfones, and these addition reactions have been studied widely. In this section, the addition of carbon nucleophiles to a, ji-unsaturated sulfones and the reactions of the resulting a-sulfonyl carbanions will be examined. 

The following table lists common names, position of ring substitution, and approximate activity of the amphetamine derivatives for some readily available allyl and propenyl benzenes (see J. Chromatography 30,54(1967) for further information on these compounds). Activity is relative to mescaline which equals 1 (an activity of 12 means a dose of about 25 mg). Parentheses indicate a methylenedioxy bridge other substituents are methoxy groups. 

From equation 10 with phenyl lithium as the benchmark species, RLi, and the hydrocarbon compounds, R H, in their reference gaseous states, the derived enthalpies of formation of allyl, ii-l-propenyl, 2-propenyl and ethyl lithium, are —12.8, —7.3, 54.3 and —58.3 kJmoP, respectively. The first and last of these are remarkably consistent with the values in Table 1. 

The present method offers a more efficient and convenient two-step route to the parent a,B-unsaturated acylsilane derivative. The first step in the procedure involves the conversion of allyl alcohol to allyl trimethylsilyl ether, followed by metalation (in the same flask) with tert-butyllithiura at -75°C. Protonation of the resulting mixture of interconverting lithium derivatives (2 and 3) with aqueous ammonium chloride solution furnishes (1-hydroxy-2-propenyl)trimethylsilane (4), which is smoothly transformed to (1-oxo-2-propenyl)trimethylsilane by Swern oxidation. The acylsilane is obtained in 53-68% overall yield from allyl alcohol in this fashion. 

Treatment of the (—)-menthone-derived 2/7-1,3-benzoxazin-4(3//)-one 202 with triflic anhydride gave the triflate 203 in quantitative yield. Palladium-catalyzed cross-coupling of 203 with 2-pyridylzinc halide resulted in formation of an approximately 3 1 mixture of the 4-(2-pyridyl)-2//-l,3-benzoxazine 204 and a 4-imino-l,3-benzodioxane derivative 205 (Scheme 36). Compound 205 was formed by the isomerization of 203, which occurred with complete retention of stereochemistry. The 4-(2-pyridyl)-l,3-benzoxazine derivative 204 was applied in enantioselective allylic alkylations of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate as a chiral ligand inducing a 62% ee in the product <2005JOM(690)2027>. 

Allylic a-bromo boronic l,l,2,2-tctramethyl-l,2-ethanediyl esters are too labile to permit preparation in high stereochemical purity. Finacol l-bromo-2-propenylboronate with sodium methoxideyields 1-methoxy-2-propenyl boronic l,l,2,2-tetramethyl-l,2-ethanediyl ester54. Attempted conversion of the corresponding chloro boronic ester to alkoxy derivatives failed54. 

Fluorinated vinylzinc reagents readily react (particularly with Cu(I)X catalysis) with allyl halides at room temperature (equation 63)57. With a substituted allyl halide, the 2-propenyl reagent gave products of both a- and -attack. The predominant product is derived from attack at the less hindered position (equation 64)5. 

Protection of primary amines cf. 8, 437). I.aguzza and Ganem- recommend the diallyl derivatives for protection of primary amines. These compounds are prepared by reaction of the amine with allyl bromide and cthyldiisopropylaminc. Dc-protcction is accomplished by isomerization of the allyl groups to propenyl groups by Wilkinson s catalyst (5. 736) in refluxing aqueous acetonitrile. Under these conditions the resulting cnaminc is hydrolyzed with evolution of propionaldchyde, and llte amine is obtained in 65 90", yield. 

Katritzky, A. R. Li, J. Malhotra, N. N-Vinyl, N-allyl, N-propenyl and N-propargylbenzotri-azoles reactions of their lithium derivatives. Liebigs Ann. Chem. 1992, 843—853. 

---