Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
42.16.1.1.2.3.2 Variation 2: Solid-Phase Phosphoramidites for Selective Monophosphorylation of ­Carbohydrates and Nucleosides

DOI: 10.1055/sos-SD-042-00920

McKenna, C. E.; Kashemirov, B. A.; Błażewska, K. M.Science of Synthesis, (200942786.

An alternative solid-phase approach exploiting phosphoramidite chemistry is to immobilize the reagent instead of its substrate. Polymer-bound phosphoramidite reagents (e.g., 18) can be used for selective monophosphorylation of carbohydrates or nucleosides with multiple hydroxy groups (Scheme 8).[‌25‌,‌26‌] In this approach, the substrate alcohol (or polyol) is treated with the immobilized phosphoramidite reagent. Unreacted alcohol is then easily removed by washing. The resin suppresses intermolecular reactions, even when swelling resins are used, and can, in principle, completely eliminate such processes if ­rigid resins are used, potentially resulting in monophosphitylation of polyols by the immobilized reagent. The intermediate phosphite 19 is then oxidized with 56M tert-butyl hydroperoxide to give the corresponding polymer-bound phosphate triesters 20. Removal of the cyanoethoxy group with 1,8-diazobicyclo[5.4.0]undecan-7-ene for 48hours at room temperature gives the immobilized phosphate ester 21. Cleavage from the resin with dichloromethane/trifluoroacetic acid (1:1) for 30minutes then provided the monophosphorylated product 22 with an overall yield of 4161%.

Meeeee 8 Meeeeeeee Meeeeeeeeeeeeeeeeee ee Meeeeeeeeeeee eee Meeeeeeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

8-M-Meeeeeeee-α-M-eeeeeeeeeeeee (88, M8=α-M-Meeeee-8-ee); Meeeeee Meeeeeeee:[‌88‌]

α-M-Meeeeee (888ee, 8.8eeee) eee 8M-eeeeeeeee (88ee, 8.88eeee) eeee eeeee ee eee eeeeeeeeeee eeeeeee 88 (888ee, 8.88eeee·e8) ee e eeeeeee ee eeeee MMM (8eM) eee MMMM (8eM), eee eee eeeeeee eee eeeeee ee ee eee 88e. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeeeeeeeeeee eeee MMMM (8 × 8eM), MMM (8 × 8eM), eee MeMM (8 × 8eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeeeee eeeeeeeee 88. M 88M eeee ee e-MeMMM ee eeeeee (888 µM, 8.8eeee) eee eeeee ee eee eeeee 88 (~888ee) ee MMM (8eM), eee eee eeeeeee eee eeeeee ee ee eee 8e. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeeeeeeeeeee eeee MMMM (8eM), MMM (8 × 8eM), eee MeMM (8 × 8eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeeee eeeeeeeeee 88. Mee eeeee 88 (~888ee) eeeeeee ee MMM (8eM) eee eeeeeee eeee MMM (888 µM, 8.8eeee), eee eee eeeeeee eee eeeeee eee 88e ee ee. Mee eeeee eee eeeeeeeee ee eeeeeeeeee, eeeeee eeee MMM (8 × 8eM) eee MeMM (8 × 8eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeee eeeee 88. Mee eeeeeee eeeee 88 (~888ee) ee eeeee MM8Me8 (8eM) eee eeeeeee eeee MM8Me8/MMM (8:8; 8eM) eeee eeeeeee eee 88eee. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeee MM8Me8 (8eM), MMM (8eM), eee MeMM (8eM). Mee eeeeeeee eee eeeeeeeeeee eeeeeeeeeeee ee 88°M, eee eee eeeeeeeee eeeeeee eee eeeeeee eeee Meeeeeeee MM-88M-M8 (888888 eeee, M+ eeee; 888ee, 8.8 eee·e8) ee M8M/8,8-eeeeeee (8:8; 8eM) eee 88eee ee 88°M. Mee eeee eee eeeeeeee eee eeeeeeeeeeee ee eeee e eeeee eeeeeee, eeeee eee eeeeeeee ee eeeeeeeeeeeeee (M88 Mee-Mee). Mee eeeeeee eee eeeeeee eee eee eeeeeee eee eeeee eeeee eeeeee; eeeee: 88% (eeeeeee).

References


Cookie-Einstellungen