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Under palladium catalysis, Et3B nicely promotes allyl alcohols to undergo C3-selective allylation of indoles and tryptophan; the yields range 75-95%.

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Palladium/Et 3 B induces allyl alcohols to undergo electrophilic allylation of soft carbonucleophiles (pK a 5-14), alkyl aldehydes at the α-position, and amines, indoles, and tryptophan at the 3-position. The same catalyst, and also Pd/Et 2 Zn, also effect the generation of allyl anions from allyl alcohols, which react with aromatic and aliphatic aldehydes and imines to furnish homoallyl alcohols and homoallylamines, respectively, in good yields. 2-Methylenepropane-1,3-diol

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Ni(acac)(2) catalyzes homoallylation of aldehydes with 1,3-dienes in the presence of triethylborane. Triethylborane serves as a reducing agent delivering a formal hydride to the C2 position of 1,3-dienes, thus generating a formal homoallyl anion species and enabling the novel homoallylation of aldehydes. The reaction proceeds smoothly at room temperature in the absence of any phosphane or nitrogen ligands and is highly regioselective and stereoselective for a wide variety combination of aldehydes and 1,3-dienes: e.g., isoprene and benzaldehyde combine to give a mixture of anti- and syn-1-phenyl-3-methyl-4-penten-1-ol (2.2) in a ratio of 15:1 in 90% yield. Under the conditions, sterically congested aliphatic aldehydes and ketones show low yields. In such cases, diethylzinc serves as a substitute for triethylborane and yields the expected products in good yields with similarly high regio- and stereoselectivity. 1,3-Cyclohexadiene is one exception among 24 kinds of dienes examined and undergoes allylation (not homoallylation) selectively.

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