An efficient synthesis of alkenyl and alkynyl silyl ethers

A New Entry to the Stereoselective Introduction of an Ethynyl Group by a Radical Reaction: Synthesis of the Potential Antimetabolite 2′‐Deoxy‐2′‐C‐ethynyluridine

“…The reaction was carried out with EDMS and TEDMS ethers of a variety of iodohydrins as substrates, which were prepared with EDMS‐Cl13 or TEDMS‐NMe 2 14 (Table 1). We first examined the radical atom‐transfer reaction with the TEDMS and EDMS ethers of 2‐iodoindanol ( 8 a and 8 b ) under various conditions, and found that when the substrate was treated with Et 3 B (0.3 equiv) at room temperature in toluene under argon, the expected atom‐transfer cyclization proceeded effectively, and immediate treatment of the product, without purification, with tetrabutylammonium fluoride (TBAF) gave the desired ethynyl product 15 15 in high yield (Table 2, entries 1 and 2).…”

Ene cyclisations of α-(prenyl)dialkylsilyloxy aldehydes: formation and oxidative cleavage of oxasilacyclohexanols

“…The solvent was removed under reduced pressure and the resulting oil was purified by flash column chromatography on silica gel (25 : 1, petrol : ether) to give the product as a colourless oil (1.46 g, 84%). R f 0.35 ( ϩ , 5%), 361 (100), 333 (12), 244 (9), 216 (10), 167 (14).…”

Highly Diastereoselective Intramolecular Allylation Reactions of Mixed Silyl-Substituted Acetals

“…Unfortunately, chlorodimethyl-substituted allylsilanes which could be employed in the reverse Brook rearrangement method are not readily available. A number of approaches to the synthesis of bifunctional silanes have been reported from dichlorodialkylsilanes or (dialkylamino)alkoxydialkylsilane derivatives; however, earlier studies in our group had indicated that nucleophilic addition of α-alkoxy anions to silyl halides or silyl ethers was not a synthetically useful process . Our initial attempts to solve this problem involved chemoselective functionalization of dimethylphenyl(α-hydroxyhexyl)silane 3 .…”

“…Given the fact that alkoxy groups are readily displaced from silicon by reaction with alkyllithio species, we then explored an alternative route to synthesize a methoxy substituted (α-alkoxyalkyl)dimethylsilane. We anticipated that ozonolysis of allyl silane 2a or 2b in methanol would result in an unstable α−trialkylsilyl aldehyde …”