Crotyl trichlorosilane

A terpene-derived pyridine N-oxide catalyses the asymmetric allylation of aldehy- des with allyl- and crotyl-trichlorosilane at —40 C, and the ees hold up well even at ambient temperature.189... 

Cp2Ni in HMPA at 90 °C. The reaction of ( T)-crotyl chloride with ClsSiH and BU4PCI at 150 °C has also been reported. ( -crotyl trichlorosilane, on the other hand, was prepared via the 1,4-addition of CHSiH to butadiene, catalyzed by (Ph4P)4Pd (at 20 °C or -78 or by (PhCN)2PdCl2 this hydro-... 

Stoichiometric asymmetric allylation of (V-benzoyl hydrazones derived from aromatic and heteroaromatic aldehydes can be attained with pseudoephedrine chelates derived from allyl and ( )- and (Z)-crotyl trichlorosilanes with excellent diastereo- and enantioselectivity (eq 7) note the opposite relative configuration at the vicinal centers of the product compared to that obtained in the aldehyde allylation (eq 4), resulting from different orientation in the transition state. ... 

N., and Maruoka, K. (2000) Tetrahedron, 56, 5373 (e) For the synthesis of trans-crotyl trichlorosilane carrying other substituents, see Maikov, A.V., Kysilka,... 

Chiral Lewis-basic catalysts (Figs. 7.1 and 7.2), in particular phosphoramides 8-12 [9, 14c, 15c, 22-24], formamide 13 [17], pyridine N,N -bisoxides 17 and 18 [25-27], N-monoxides (19-26) [27-32], and N,N N"-trisoxides (27) [33] exhibit good to high enantioselectivities for the allylation of aromatic, heteroaromatic, and cinnamyl-type aldehydes (1) with allyl, trans- and ds-crotyl, and prenyl trichlorosilanes (2a-d). Chiral formamides (with the exception of 13, as discussed below) [17], pyridine-oxazolines [34], urea derivatives [19] and sulfoxides [35] are effective only in stoichiometric quantities (or in excess) and, as a rule, exhibit lower enantioselectivities. 

Asymmetric allylation and crotylation reactions using allylic trichlorosilanes and chiral phosphonamides were developed by Denmark and coworkers in 1994 and further refinement of the chiral ligands system was made in 200114 (Scheme 3.2k). The influence of the six-membered chairlike transition state is once again evidenced by the excellent correlation of the geometry of the reacting silanes with the diastereomeric composition of the products. Thus, anti -isomer is obtained from the -allylic silane, and syn-isomer is produced from the Z-silane. Based on... 

Dimeric phosphoramides have recently been demonstrated to be superior to the monomeric versions for allylations and crotylations using allylic trichlorosilanes, see reference 21b. 

Chiral Lewis-basic catalysts, in particular phosphoratnides (1 and 2),2-13c. 16.46,47 pyridine iV,iV-bisoxides (3 and and pyridine iV-monoxides (5, 6 and 7,8),3 exhibit very high enantioselectivities for the allylation of aromatic, heteroaromatic, and cinnamyl-type aldehydes with allyl, ( )- and (Z)-crotyl, and prenyl trichlorosilanes. Chiral formamides, pyridine-oxazolines, urea derivatives, and sulfoxides are generally less enantioselective and effective only in stoichiometric quantities. The reaction is much less efficient with aliphatic aldehydes, which require stoichiometric conditions (vide infra). However, a, -unsaturated aldehydes do react readily and give 1,2-addition products. 

A solution of ( )-crotyl chloride (5.4 g, 60 mmol) and trichlorosilane (11.7 g, 86 mmol) in diethyl ether (10 mL) is added to a suspension of copper(I) chloride (0.20 g, 2.0 mmol) and triethylamine (7.2 g, 71 mmol) in diethyl ether (30 mL) at it. The reaction mixture is stirred for 1.5 h, and insoluble materials are filtered off. The filtrate is concentrated the residue is distilled to give ( )-crotyltrichlorosilane in 76% yield. SbFe (15.3 g, 86 mmol) is placed in a 50-mL flask and heated under vacuum for 2 h for drying. To this is added ( )-crotyltrichlorosilane (9.9 g, 52 mmol) drop by drop. An exothermic reaction takes place and... 

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