Ring cleavage of THP and THF ethers using dimethylboron bromide

✍ Scribed by Yvan Guindon; Michael A Bernstein; Paul C Anderson

• Book ID: 104227575
• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 256 KB
• Volume: 28
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)96086-6

✦ Synopsis

The reactlon of dlmethylboron bromlde with THP and THF ethers was studled. Under condltlons of klnetlc control. these reacttons proceed by selective cleavage of the ring carbon-oxygen bond to glve acyclIc a-bromo ethers. Treatment of these lntermedlates with a variety of nucleophiles gives ring-opened products. Olmethylboron bromide (Me2BBr) has recently been described by our laboratories as a mild and selective reagent for the cleavage of acetals and ketals (including MEH. MOH and MTH ethers) to the corresponding aldehydes, ketones or alcohols. 2a,b Whlle most simple acetals and ketals (Including acetonldes. HEM and MOM ethers) were cleaved efficiently at -78°C. tetrahydropyranyl (THP) and tetrahydrofuranyl (THF) ethers requlred more forcing condltlons (B-18 h, room temperature) to generate the parent alcohol.2b The unexpected difference In reactivity between these classes of acetals has led us to re-examine these reactions and It Is these results whjch we are now reporting.