Allyl using

The synthetic utility and generality of the reaction is demonstrated by an intramolecular/intermolecular double allylation using an oo-dienyl aldehyde 38 as a probe. The internal diene terminus selectively undergoes nucleophilic allylation intramolecularly to form a cyclopentanol structure. The terminal... 

Scheme 51 Allylations using an acyclic template sulfonamide...

Scheme 56 Radical allylations using chiral lanthanide Lewis acids... 

Palladium-catalyzed allylation using nucleophiles with allylic halides, acetates, carbonates, etc. via intermediate allylpalladium complexes, and typically with overall retention of stereochemistry. 

Hunter R, Michael JP, Tomlinson GD (1994) Allylation using allylborates. Tetrahedron... 

Scheme 6 Bi(OTf)34H20-catalyzed allylation using a functionalized allylsilane...

The most detailed and thorough studies on asymmetric catalytic allylation using palladium chiral phosphine complexes have come from the work of Bosnich et a/.443 45 Employing a combination of NMR, chemical and labelling studies on this process, this group was able to determine that with 1,1-diphenyl-3-... 

Methylacridinium ion also underwent allylation using allyltrimethylsilanes under photochemical conditions (equation 36)176. 

Chiral N-oxides of type (S)-165 can be also used for diastereo- and enantioselec-tive allylation using ( )- and (Z)-crotyltrichlorosilanes [176]. For these substrates, high diastereoselectivity led to the anti-diastereomer when ( )-crotyltrichlorosilane, 158b, was used and the syn-diastereomer when the (Z)-substrate, 158c, was used (Scheme 6.77). For example, formation of the anti-diastereomer (R,R)-159e proceeded with 68% yield and excellent diastereoselectivity of d.r. (syn/anti) = 3 97. Enantiomeric excess for the major anti-diastereomer (R, )-159e was 86%. 

In more detail these pathways and their coupling with Lewis-acid-catalyzed allylation using allyltrimethylsilane are shown in Scheme 14 <2000J(P1)3006>. 

Fluoride ion (from CsF, CdF2, or AgF) can also catalyze the allylation using AllylSiF3 and AllylSi(OMe)3, respectively [10, 11] the asymmetric version (with <56% ee) requires a combination of Bu4N+[SiPh3F2] with the Lewis acidic complex of CuCl and BINAP [21]. 

Carbonyl allylation using pentacoordinate allylsilicates is valuable for stereospecific synthesis of homoallyl alcohols ... 

Homochiral strained allylsilacycles 24 are valuable for uncatalyzed enantioselective allylation of (V-acy I hydrazones derived from aldehydes and ketones (Equation (32)).133,133a The crotylation using 24b and 24c occurs in the same stereospecific manner as observed in the DMF-promoted crotylation using crotyltrichlorosilanes. A cyclic transition state similar to 22 is reasonable also in the allylation using 24. 

The metal allyls can provide a large variety of an-chorcd/grafted species with different oxidation states after subsequent thermal treatments. They are involved as model catalysts in various catalytic reactions hydrogenation, oxidation, metathesis, isomerization, or polymerization. The most widely studied metal allyls are Mo and Cr. A list of the metal allyls used as precursors for anchoring/grafting as well as their catalytic applications can be found in Table 5 of Ref. 15. 

Asymmetric allylation using optically active allylic siliconates has been reported [96]. The allylic siliconates were prepared by asymmetric hydrosilylation of 1,3-dienes and HSiCla catalyzed by a chiral palladium catalyst followed by ethanolysis. Complete asymmetric induction of allylic siliconates to homoallylalcohols was accomplished (Sch. 55). 

In the laboratory of B.M. Trost, a modular approach toward the total syntheses of furaquinocins was developed. To introduce the homoallylic side chain in a diastereoselective fashion, they utilized the Sakurai allylation reaction. During their studies they found that the highest diastereoselectivity can be achieved using 1 equivalent of TiCU at room temperature. Application of other Lewis acids such as BF3 OEt2 gave the product with lower selectivity. Attempts to perform the allylation using catalytic amounts of Lewis acids such as FeCIs or Sc(OTf)s led to no conversion. The resulting homoallylic alcohol served as a common intermediate toward the syntheses of both furaquinocin A and B. 

Excellent yields and diastereoselectivities have been obtained in allylations using a new oxazolidinone chiral auxiliary derived from diphenylalaninol [24]. The use of oxazolidinone chiral auxiliaries was sparked by the application of Lewis acids to radical reactions. Bidentate Lewis acids are used to favor one rotamer (44) out of a possible four by forming a chelated intermediate with the two carbonyl groups and through steric interactions imparted by the 4-substituent of the oxazolidinone (Eq. (13.12)). Trapping with the allylstannane can then occur on the face opposite the bulky oxazolidinone-4-substituent. 

Table 13-2. Diastereoselective allylations using oxazolidinone auxiliaries.

Trost and coworkers developed a chiral zinc phenoxide for the asymmetric aldol reaction of acetophenone or hydroxyacetophenone with aldehydes (equations 62 and 63) . This method does not involve the prior activation of the carbonyls to silyl enol ethers as in the Mukaiyama aldol reactions. Shibasaki and coworkers employed titanium phenoxide derived from a phenoxy sugar for the asymmetric cyanosilylation of ketones (equation 64). 2-Hydroxy-2 -amino-l,l -binaphthyl was employed in the asymmetric carbonyl addition of diethylzinc , and a 2 -mercapto derivative in the asymmetric reduction of ketones and carbonyl allylation using allyltin ° . ... 

Scheme 4.6 Indium-mediated allylation using cinchonidine as a ligand.

To achieve asymmetric allylation with allylsilanes, the control of absolute configuration by use of chiral auxiliaries was extensively studied in the nineteen-eighties. Recently, much effort has been directed toward the use of optically active a-chiral allylsilanes and catalytic asymmetric allylation using chiral Lewis adds and bases. 

---