F Allyl bromide

Reaction conditions A MeOH (1 equiv.) B CuCN (1 equiv.) C ethyl 2-(bromomethyl)acrylate D nitrostyrene E MeaSnCI (1 equiv.) F allyl bromide G i-BuOH (1 equiv) (E)-1-iodo-l-butene, Pd(PPh3) cat I CITi(OiPr)3 (2 equiv.), benzaldehyde (1.5 equiv.). 

Scheme 3 Reagents, (a) Allyl bromide/Acetone followed by optical resolution (b) Benzyl chloroformate, NaHC03 (aq), CHC13(98%) (c) Pd/C, H20, AcOH (100%) (d) di-tert-butyl dicarbonate, CH2C12 (98%) (e) Pd/C, Ammonium formate, MeOH (97%) (f) Allyl bromide, K2CQ3, Acetone (98%) (g) TFA, Triethylsilane, CH2C12(89%) (h) Pd/C, H2Q, AcOH [60]...

Allyl benzene sulfonate, 3155 f Allyl bromide, see 3-Bromo-l-propene, 1153 f Allyl chloride, see 3-Chloropropene, 1158... 

The possible routes leading to azides 2 are outlined in Scheme 1. The only pathway which we can exclude the 2=>C=>D=>E=>2 sequence since neither intermediate E nor its possible derivative E could be detected in the reaction mixture. (P-Azido a,P-unsaturated ketones are known to afford isoxazoles via nitrenes derived by loss of nitrogen (refs. 4,10). Azides 2 may form either via intermediate A (Sn + E route) or via allyl bromide-type intermediate B (E -f Sn route), both routes may operate on the basis of experimental results obtained so far. 

Allylic bromination of 235 with excess CuBr and PhCCb-f-Bu (1 1 molar ratio) gives the separable allylic bromides 236 and 237 with 62% and 15% yield, respectively. Further treating the allylic bromide 236 with CuBr in CH3CN at 50° C leads to a mixture of 236 and 237, from which 25% of 236 and 69% of 237 can be separated. 

Propose a synthetic approach f or the preparation of allylic bromide 8... 

Alkylation of cyclopropanecarboxylic acid esters,6 Deprotonation of methyl silyloxycyclopropanecarboxylates (1), prepared as shown, is possible with LDA in THF at — 78°. The resulting anions react with primary alkyl iodides and benzylic or allylic bromides to give 2 in high yield. These products are cleaved by F to methyl 4-ketocarboxylates 3. 

Catalyst screening experiments resulted in the discovery that copper(salen) complex 33 was a highly effective catalyst for the conversion of alanine derivative 16b into (f )-a-methyl phenylalanine 17 under the conditions shown in Scheme 8.16. The presence of just 1 mol% of catalyst 33 was sufficient to induce the formation of compound 17 with up to 92% ee and in >70% yield [33]. Allyl bromide, 1-chloromethylnaphthalene and ethyl iodide also reacted with substrate 16b to give the corresponding (H)-a-methyl a-amino acids in the presence of 2 mol % of complex 33 [34], Complex 33 also catalyzed the asymmetric mono-alkylation of glycine-derived substrate 34 by benzylic or allylic halides, to give (H)-a-amino acid derivatives 35 with 77-81% ee. and in greater than 90% yield, as shown in Scheme 8.17. 

Preparation of Allyl Phenyl Ether, f A mixture of 188 g. of phenol, 242 g. of allyl bromide, 280 g. of finely ground calcined potassium carbonate, and 300 g. of acetone is refluxed on the steam bath for eight hours. A heavy predpitate of potassium bromide begins to form soon after the refluxing is started. After cooling, water is added the product is taken up in ether and washed twice with 10% aqueous sodium hydroxide solution. The ether solution is dried over potassium carbonate, and, after removal of the ether, the residue is distilled under diminished pressure. The yield is 230 g. (86%), b.p. 85°/19 mm., dll 0.9845. The residue is so small (6 g.) that the distillation might be omitted unless a very pure product is desired. About 1% of allyl 2-allylphenyl ether (a product of C-alkylation) is formed by this procedure. 

Allylation of indole 160 (obtained from indole in 85% overall yield, five steps) with allyl bromide in the presence of CS2CO3 led directly to l-allyl-2-ethynyl-l/f-indole 161 with loss of the trimethylsilyl group in the same reaction (Equation 29) <2002S1810>. 

An interesting example of the solvent-dependent cycloreversion of a substituted 3/f-A -pyrazoline (formed by the 1,3-dipolar cycloaddition of diazomethane to an allylic bromide) has been given by Kolsaker et al. [675]. 

When treated with benzoic acid in the presence of triphenylphosphine and diethyl azodicarboxylate, benzophenone oxime gave a high yield of f -benzoylbenzanilide (14), formed via rearrangement of the intermediate 0>benzoyloxime (15). Reaction of p>medioxyaGetophenone oxime with l,rsubstituted derivative (l ), whereas in the presence of allyl bromide... 

Telluronium Allyl bis-[2-methyl-propyl]- (Bromide) E12b, 683 (R2Te -f Allyl-Br)... 

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