Allylations allyl trichlorosilane

Allylic trichlorosilanes have shown promise in the development of methods for enantioselective reactions by use of chiral phosphoramides such as C. 

S)-Prolinc-dcrivcd phosphoramides catalyse enantioselective allylation of aromatic aldehydes with allylic trichlorosilanes.90 Chiral a-aminoaldehydes have been allylated diastereoselectively with various reagents.91... 

Stereo specific generation and reactions of allylic alkali and alkaline earth metals have been reviewed121 and solvent-mediated allylation of carbonyl compounds with allylstannanes has been explored.122 Chiral phosphoramides derived from (5 )-proliiie have been used to catalyse asymmetric allylation of aromatic aldehydes by allylic trichlorosilanes.123... 

Chiral phosphoramides have been developed as catalysts for asymmetric addition of allylic trichlorosilanes to aldehydes.176 Although some des were high, ees were modest. Kinetic studies suggest dual mechanisms, and thus a route to the design of more highly selective catalysts. 

Scheme 7.2 Lewis base-catalyzed allylation of aldehydes 1 with allyl trichlorosilanes 2a-d.

Allyl trichlorosilane is conveniently prepared from allyl chloride, Cl3 SiH, CuCl, and (i-Pr)2EtN (or Et3N) in ether at 20 °C (a) Kobayashi, S., Nishio, K., Chem. Lett. 1994, 1773 (b) Nakajima, M., Saito, M., Hashimoto,... 

Allyl trichlorosilane (0.47 mmol) was added to a solution of the METHOX catalyst (0.02 mmol), diisopropylethylamine (2 mmol) and aldehyde (0.4 mmol) in acetonitrile (2 mL) under nitrogen at — 40 °C. The mixture was stirred at the same temperature for 18 h, after which the reaction was quenched with aqueous saturated NaHC03 (1 mL). The aqueous layer was extracted with ethyl acetate (3 x 10 mL) and the combined organic extracts were washed with brine and dried over Na2S04. The solvent was removed in vacuo and the residue purified by FC on a silica gel column (15 cm x 1 cm) with a petroleum ether-ethyl acetate mixture (95 5) to produce (S)-(—)-l-phenyl-but-3-en-l-ol (95%, 96% ee). 

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... 

ALLYLSENFOEL (GERMAN) see AGJ250 ALLYL SEVENOLUM see AGJ250 ALLYL THIOCARBONIMIDE see AGJ250 ALLYL TRICHLORIDE see TJB600 ALLYL TRICHLOROSILANE see AGU250 ALLYLTRICHLOROSILANE, stabilized (DOT) see AGU250... 

Various chiral allylic trichlorosilanes and dichloro(methyl)silanes obtained in this way were transformed into chiral fluorosilanes on treatment with copper fluoride14. 

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

Pentacoordinate silicon, in the form of allyltrichlorosilane, in the presence of DMF or HMPA, also undergoes allylation with aldehyde [97,98], The Lewis base-promoted approach has the merit of operational convenience. Stereoselective formation of allylic trichlorosilanes is achieved by copper-catalyzed coupling of allylic chloride and trichlorosilane or by palladium-catalyzed hydrosilylation of 1,3-dienes (Sch. 56) [99],... 

Chiral phosphorarnides, as developed by Denmark during the late 1990s [25], are efficient catalysts for the allylation of aldehydes with allyl trichlorosilane [26a] or the aldol condensation of trichlorosilyl-enol ethers with aldehydes [26b]. However, the first example of supported chiral phosphorarnides on a polymeric matrix was reported only in 2005 [27]. 

The reaction of 2-chloropropene, trichlorosilane, and amine in the presence of a catalytic amount of copper(l) chloride proceeds smoothly under mild conditions to give allyl-trichlorosilane in highyield (equation 32). 

Synonm Allyl Alcohol Allyl Bromide Allyl Chloride Allyl Chlorocarbonate Allyl Chloroformate Allylsilicone Trichloride Allyl Trichlorosilane Aluminum Chloride... 

---