Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via
37.3.1.1.1 Method 1: Synthesis from 3-Halopropanols (The Williamson Synthesis)

DOI: 10.1055/sos-SD-037-00246

Griesbeck, A. G.; Sokolova, T.Science of Synthesis, (200837434.

This simple approach to cyclic ethers (compared to the dehydration of 1,3-diols), i.e. the Williamson ether synthesis, is less frequently found in oxetane chemistry. This is due to the lack of availability of 3-bromoalkan-1-ols compared to 2-bromoalkan-1-ols. A straightforward strategy is the selective conversion of 1,3-diols (available from aldol products by reduction) into 3-bromoalkan-1-ols followed by base-induced oxetane ring formation. Diastereomerically pure 1,3-diols 8 with a phenyl group at C1 are transformed into esters of 3-bromopropan-1-ols 9 by treatment with trimethyl orthoacetate and acetyl bromide. Deprotection of the intermediate 3-bromopropyl acetates with diisobutylaluminum hydride and subsequent reaction with sodium hydride furnishes the oxetanes 10 with overall retention of configuration at both stereogenic centers (Scheme 3).[‌21‌] A shorter reaction protocol involves direct conversion of the 3-bromopropyl acetates into oxetanes by treatment with methanol and sodium hydride (method B to prepare trans-10, Scheme 3). 2,3,4-Trisubstituted oxetanes may also be synthesized by this protocol.

Meeeee 8 Meeeeeeeee Meeeeee Meeeeeeee eeee 8-Meeeeeeeeee Meeeeeee[‌88‌]

M eee eeee ee eee ee eee eeeee eeeeeeeee ee Meeee ee eee eeeeeee (M-eeee) eeeeeeeee ee eeee eeeeeee ee e eeeee-8-eeeeee-8-(eeeeeeeeeeeee) eeeeeeee ee eeeeeeeee eeee eee eeeeee eeee 8,8-eeeeeeeeeeee[8.8.8]eee-8-eee.[‌88‌] Mee eeeeeeee eee eeee ee eeeeeeeee eeee e eeeeee eeeee ee eeeeeeeeeeee eee eeee eee eeeeeeeeeeeeee eeeeeeee eeeeeeeeeeee.[‌88‌] Meee eeeeeeeeeeeeeeeeeeee eeeeeeeee, eeeeeeee eee eeeee ee M-eeeeeeeeeeee eeeeeeeeeeee ee eeee eeeeeeee ee eee eeeeeee eeeee ee ee ee eeeeeeeeeee eeeeeeee eee M-eeeeeeeeee ee eeee eeeeeeeee. Mee eeeeeeee eeeeeeeeee 88 ee eeeeeeee ee eeeeeee (8,8-eeeeeeeeeeeeee-8-eeeeeee)eeeeeeee (88) ee 88% eeeee ee eeeeeeeee eeee eeeeee eeeeeee ee eeeeeeeeeeeeeee (Meeeee 8).[‌88‌]

Meeeee 8 Meeeeeee Meeeeeeeeee Me Meee ee Meeeeee Meee[‌88‌]

Mee eeee eeeeeee eeeeeeeee ee eee Meéeeee eeeeeeee ee eee eeeeeeeeeeeee eeeeeee eeeeeee 88, eeeee eee eeeeeeeeeeee 88 eeee eeeeeee eeee 8,8-eeeeeeeeeeee[8.8.8]eeeee-8-eee, eeeeeee eeeeeeeee ee eee eeeeeee (ee eeeeeee eeeeeeeeeeee, Meeeee 8). Mee eee eeeeee eee eee eee-eeee eeeeeee eee eee ee eee eeeeeeeee ee e eeee-eeeeeeeeeee eeeeeee eeeeee eee Meéeeee eeeeeeee.[‌88‌]

Meeeee 8 Meeeeee Meeeeeeee eeee ee Meeeeee Meeeeee ee Meéeeee Meeeeeee eee Meeeeeeee Meee Meeeeeeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

eeeee-8-Meeeeeeeee-8-eeeeeeeeeeeee (88); Meeeeee Meeeeeeee:[‌88‌]

Me e eeee ee eee eeee eeee-8 (888ee, 8.88eeee) ee MM8Me8 (8eM) eee eeeee MeM(MMe)8 (888 μM, 8.88eeee) eee MMMM (8ee). Mee eeeeeee eee eeeeeee eee 88eee, eeeeee ee 88°M, eee MeMe (888 μM, 8.8eeee) eee eeeee. Mee eeeeeee eee eeeeeee eee 8.8e, eeeeeeee eeee eee. ee MeMMM8, eeeeeeeee eeee MM8Me8 (8×8eM), eeeee (MeMM8), eeeeeeee, eee eeeeeeeeee ee eeee eee eeeee eeeeeee. Meee eeeeeeee eee eeeeeeeee ee eee MMM (8eM), eee MeMM (88eM, 8.88eeee) eee 88% MeM eeeeeeeeee ee eeeeeee eee (888ee, 8.8eeee) eeee eeeee. Mee eeeeee eee eeeeeee ee eeee eee eee eeeeeee eee eeeeeee eee 88e ee 88°M, eeeeeeee eeee M8M, eee eeeeeeeee eeee MeMMe (8×88eM). Mee eeeeeeee eeeeeee eeeeeeee eeee eeeee (MeMM8), eeeeeeee, eee eeeeeeeeee, eee eee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee; eeeee: 88ee (88%).

References


Cookie-Einstellungen