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Please login to access the full content or check if you have access via42.16.1.1.2.3.2 Variation 2: Solid-Phase Phosphoramidites for Selective Monophosphorylation of Carbohydrates and Nucleosides
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McKenna, C. E.; Kashemirov, B. A.; Błażewska, K. M., Science of Synthesis, (2009) 42, 786.
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 5–6 M 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 48 hours at room temperature gives the immobilized phosphate ester 21. Cleavage from the resin with dichloromethane/trifluoroacetic acid (1:1) for 30 minutes then provided the monophosphorylated product 22 with an overall yield of 41–61%.
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 (888 ee, 8.8 eeee) eee 8M-eeeeeeeee (88 ee, 8.88 eeee) eeee eeeee ee eee eeeeeeeeeee eeeeeee 88 (888 ee, 8.88 eeee·e−8) ee e eeeeeee ee eeeee MMM (8 eM) eee MMMM (8 eM), eee eee eeeeeee eee eeeeee ee ee eee 88 e. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeeeeeeeeeee eeee MMMM (8 × 8 eM), MMM (8 × 8 eM), eee MeMM (8 × 8 eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeeeee eeeeeeeee 88. M 8–8 M eeee ee e-MeMMM ee eeeeee (888 µM, 8.8 eeee) eee eeeee ee eee eeeee 88 (~888 ee) ee MMM (8 eM), eee eee eeeeeee eee eeeeee ee ee eee 8 e. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeeeeeeeeeee eeee MMMM (8 eM), MMM (8 × 8 eM), eee MeMM (8 × 8 eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeeee eeeeeeeeee 88. Mee eeeee 88 (~888 ee) eeeeeee ee MMM (8 eM) eee eeeeeee eeee MMM (888 µM, 8.8 eeee), eee eee eeeeeee eee eeeeee eee 88 e ee ee. Mee eeeee eee eeeeeeeee ee eeeeeeeeee, eeeeee eeee MMM (8 × 8 eM) eee MeMM (8 × 8 eM), eee eeee eeeee eeeee eeeeee ee eeee eee eeeeeeeee eeeee 88. Mee eeeeeee eeeee 88 (~888 ee) ee eeeee MM8Me8 (8 eM) eee eeeeeee eeee MM8Me8/MMM (8:8; 8 eM) eeee eeeeeee eee 88 eee. Mee eeeee eee eeeeeeeee ee eeeeeeeeee eee eeeeee eeee MM8Me8 (8 eM), MMM (8 eM), eee MeMM (8 eM). Mee eeeeeeee eee eeeeeeeeeee eeeeeeeeeeee ee –88°M, eee eee eeeeeeeee eeeeeee eee eeeeeee eeee Meeeeeeee MM-88M-M8 (888–888 eeee, M+ eeee; 888 ee, 8.8 eee·e−8) ee M8M/8,8-eeeeeee (8:8; 8 eM) eee 88 eee 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
[25] | Meeeee, M.; Meeee, M. M.; Meeee, M. M., Meee. Mee. Meee., (8888) 8, 888. |
[26] | Meeeeeeeee, M.; Meeeee, M., M. Mee. Meee., (8888) 88, 8888. |