Allylation reactions of aldehydes

An extension of the asymmetric condensation of organometallics onto aldehydes is the enantioselective silver-promoted allylation reaction of aldehydes with allyltributyltin, which has recently been performed by Shi et al. in the presence of chiral diphenylthiophosphoramide ligands and more efficiently, with binaphthylthiophosphoramide ligands. According to the nature of the ligand substituents, the corresponding allylation products were obtained in enantioselectivities of up to 98% ee, as depicted in Scheme 3.70. 

By using allylation reaction of aldehydes with chiral allylic boronate A in Scheme 52, Lebreton synthesized (R)-35 and (S)-34 via ( )-B and (S)-C, respectively [78]. 

Trimethylsilyl triflate itself can not promote allylation reactions of aldehydes with allyltri-methylsilane. By using the more highly reactive system Me3SiB(OTf)4, the reactions proceed smoothly.326 A very small amount (0.2-1 mol.%) of Me3SiB(OTf)4 is enough for the reactions (Scheme 75). Allylation of acetals can be promoted by trimethylsilyl bis(trifluoromethanesulfo-nyl)imide (Me3SiNTf2),327 which is also a reactive catalyst for Diels Alder reactions.328... 

S. Kobayashi, T. Wakabayashi, H. Oyamada, Use of an Organometallic Reagent in Water Sc(OTf)3-Catalyzed Allylation Reactions of Aldehydes in Micellar Systems Chem. Lett. 1997, 831-832. 

Allylsilanes and allylboranes are allyl anion equivalents, which are stable enough to be included in subsequent allylation reactions of aldehydes under... 

In 1996, Yamamoto and Yanagisawa reported the allylation reaction of aldehydes with allytributyltin in the presence of a chiral silver catalyst.2 They found that the combination of silver and a phosphine ligand accelerates the allylation reaction between aldehydes and allyltributyltin. After this discovery, they screened several chiral phosphine ligands and found that chiral silver-diphosphine catalysts can effect the reaction in an enantioselective fashion (Table 9.1).2 For example, when benz-aldehyde and allyltributyltin were mixed in the presence of 5 mol% of AgOTf and (S)-2,2 -bis(diphenylphosphino)-1,1 -binaphthyl (BINAP), the corresponding homoallyl alcohol was obtained with 96% ee and 88% yield (Table 9.1). Generally, the reaction with aromatic aldehydes afforded the corresponding homoallyl alcohols in excellent... 

Chiral(acyloxy)boranes 523-525 were reported to be excellent catalysts for the enantioselective Mukaiyama condensation (Equation (248)) and allylation reaction of aldehydes leading to homoallylic alcohols (Equation (249)) 1042-1045... 

Tandem acetalization-allylation reaction of aldehydes with allylsilanes provides a convenient route to homoallyl ethers.82 Under catalysis by Sc(OTf)3, various aldehydes can be converted into homoallyl ethers by treatment with... 

Table 1. Enantioselective allylation reaction of aldehydes with allyltributyltin (68) catalyzed by 5 mol % (S)-BINAP-AgOTtcomplex in THF at-20 °C.

Allylsilanes and allylstannanes are known to undergo the allylation reactions of aldehydes and ketones in the presence of Lewis acids (the most commonly used are TiCU and SnCU). Zirconium Lewis acids have often been compared with the titanium analogs. For most allylation reactions using allylsilanes the best results were obtained when TiCU or SnCU was used. For allylation reactions using allylstannanes, as illustrated in Eq. (15), however, ZrCU was used as the Lewis acid to obtain the bicyclic compound 36 via the intramolecular allylation of stannylaldehyde (35) [16]. 

Bandin, M., Casolari, S., Cozzi, P. G., Proni, G., Schmohel, E., Spada, G. P., Tagliavini, E., Umani-Ronchi, A. Synthesis and characterization of new enantiopure 7,7 -disubstituted 2,2 -dihydroxy-1,1 -binaphthyls useful ligands for the asymmetric allylation reaction of aldehydes. Eur. J. Org. Chem. 2000,491-497. 

The synthesis of bis-pyran 340 was initiated by the allylation reaction of aldehyde 336b with the allylboron reagent derived from allylstannane (S)-335 and... 

Furthermore, the Sc(OTf)3-catalyzed allylation reactions of aldehydes with tetraallyltin proceeded smoothly in micellar systems to afford the corresponding homoallylic alcohols in high yields (Table 14-12) [45]. The reactions were successfully carried out in the presence of a small amount of a surfactant in water without using any organic solvents. 

In this chapter, an overview of the electrophilic snbstitntion chemistry of allyltin compounds leading to the formation of a new C—C bond is presented. Mechanistic considerations and a synopsis of information derived from detailed studies of allyltin reactions develop a perspective, which serves as a guide for planning new reactions. The major emphasis of the chapter is devoted to Lewis acid-promoted allylation reactions of aldehydes and related species. 

Scheme 4.5 Enantioselective indium-mediated allylation reaction of aldehydes.

Tab. 5.1 a-Selective allylation reaction of aldehydes or ketones with allyli c barium reagents ... 

Pd-catalyzed umpolung allylation reactions of aldehydes, ketones, and imines... 

Compared with well-established electrophilic it-allylpalladium chemisty, the catalytic asymmetric reaction via umpolung of jt-allylpalladium has received very limited exploration [93]. Zhou and co-workers investigated the Pd-catalyzed asymmetric umpolung allylation reactions of aldehydes [22a, 94], activated ketones [95], and imines [96] by using chiral spiro ligands (5)-18e, (S)-17c, and (5)-17a, respectively. One representative example is that of the Pd/(5)-18e-catalyzed umpolung allylation of aldehydes with allylic alcohols and their derivatives, which provided synthetically useful homoallylic alcohols from readily available allylic alcohols, with high yields and excellent enantioselectivities (Scheme 33). 

It was also found that the allylation reactions of aldehydes (cf. Section 6.8) with tet-ra-allyltin proceeded smoothly in micellar systems using Sc(OTf)3 as a catalyst... 

Furthermore, the Sc(OTf)3-catalyzed allylation reactions of aldehydes with tetraallyltin proceeded smoothly in micellar systems to afford the correspond-... 

For the reactions of carbonyl compounds with tetraallyltin (a) PeetWG.Tam W (1983) J Chem Soc, Chem Commun 853 (b) Daude G, Pereyre M (1980) J Organometal Chem 190 43 (c) Harpp DN, Gingras M (1988) J Am Chem Soc 110 7737. See also (d) Fuku-zawa S, Sato K, Fujinami T, Sakai S (1983) J Chem Soc, Chem Commun 853. Quite recently Yamamoto et al.has reported allylation reactions of aldehydes with tetraallyltin in the presence of hydrochloric acid (e) Yanagisawa A, Inoue H, Morodome M, Yamamoto H (1993) J Am Chem Soc 115 10,356... 

Highly Selective Allylation Reaction of Aldehydes with Allyltrifluorosi-lane / Diol / Trialkylamine... 

This chapter collects miscellaneous enantioselective nickel-catalysed reactions that could not be included in other chapters, such as cyclisation reactions, amination reactions, ring-opening reactions, Friedel-Crafts reactions, allylation reactions of aldehydes, and other reactions. It well demonstrates the remarkably diverse chemical reactivity exhibited by chiral nickel catalysts. 

Scheme 13.12 Allylation of imines catalyzed by lanthanide triflate. Table 13.12 Competitive allylation reaction of aldehydes and imines...

In 2007, Hall and coworkers have disclosed a new family of simple and efficient double allylating reagents of type (11) as stable bimetallic reagents for stereoselective allylation reaction of aldehydes (Scheme 1.16) [22]. 

In 1978, Hoffmann reported enantioselective allylation reactions of aldehydes with a camphor-derived chiral boronate 13 (Equation 1) [55]. Three classes of chiral boron reagents that furnish allylation products with very high levels of enantioselectivity have emerged Brown s diisopinocampheyl or diisocaranyl allyl boranes [35-41], Roush s tartrate-derived boronates [33, 42-48], and Hoffmann s "a-chiral boronates [56-61],... 

In pioneering studies, Yamamoto reported catalytic, asymmetric allylation reactions of aldehydes with allylsilanes in the presence of chiral acyloxy-borane complexes (CAB, 188) as shown in Equation 11 [120]. The observed enantioselectivities are impressively high for y-alkyl-substituted allylsilanes (>90% ee), but only modest for the parent allyltrimethylsilane (55% ee). 

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