1,4-Conjugate addition of allyltrimethylsilane to α,β-unsaturated ketones

The Truth about False Unicorn (Chamaelirium luteum): Total Synthesis of 23R,24S‐Chiograsterol B Defines the Structure and Stereochemistry of the Major Saponins from this Medicinal Herb

“…Allyl cuprates failed to give successful 1,4-addition and produced, at best, only trace quantities of 1,2-addition product. Allylation of enone 21 was also attempted by exposure to Sakurai conditions, [37] with successful 1,4-allylation occurring when using the modified conditions (allyl-TMS, I 2 cat., CH 2 Cl 2 , 258C) reported by Yadav et al [38] Disappointingly, 1 H NMR spectroscopy analysis showed that two diastereomers had formed in almost equal amounts. An attempt to epimerise the C-17 centre failed to alter the ratio of each diastereomer, suggesting the allylated product to be a mixture of C-20 epimers.…”

Iodotrimethylsilane-Mediated Cross-Aldol Condensation: A Facile Synthesis of α,α′-Bis(substituted benzylidene)cycloalkanones

“…Encouraged by this result, several aromatic aldehydes were successfully reacted with cyclic ketones under similar conditions to afford the corresponding a,a¢-bis(substituted benzylidene)cycloalkanones and the results are shown in Table 1. It is important to note that the cross-aldol reaction of aliphatic aldehyde with cyclohexanone (Table 1, entry j) also proceeded cleanly to give the corresponding di-aldol product in good yield, whereas the reaction of unsymmetrical cyclic ketones such as cyclohex-2-enone (entry f), indan-1-one (entry l) with benzaldehyde afforded 3-benzylidenecyclohex-2-ene-1-one and 2-benzylidineindan-1-one respectively, which can be utilized 15 for the synthesis of Michael adducts. All reactions proceeded rapidly at room temperature and complete conversion was observed within 60-80 minutes with one equivalent of TMSCl and one equivalent of NaI to give the corresponding products in 72-95% yield.…”

Allyltrimethylsilane

“…87 Allylation of acetals also proceeds smoothly when using sulfur dioxide as a Lewis acidic solvent. 91 Reaction with Acyl Chlorides. The conjugate addition of allyltrimethylsilane to conjugate enones can be catalyzed by TMSNTf 2 , which is formed in situ from HNTf 2 and allyltrimethylsilane (eq 11).…”