Solid-supported diol resins

Fully protected tumor-associated carbohydrate antigen Globo-H (50), a potential breast and prostate cancer vaccine [54, 55], was assembled by automated solid support synthesis using oct-4-ene-l,8-diol linker 49 and building blocks 51-56 (Scheme 20.15). The linker is stable to acid and base but is cleaved cleanly by olefin metathesis [56]. The octenediol linker performs best on Merrifield s PS resin, affording routinely loadings in a range of 0.1-0.3 mmol g 1. 

Acetal handle 78 synthesized from Merrifield resin and 4-hydroxy-benzaldehyde was applied to the solid-phase synthesis of carbohydrates and 1-oxacephams (Scheme 41) [90]. For the latter, a 1,3-diol was initially anchored to the support to form a cyclic acetal. A ring opening reaction with DIBAL generated a resin-bound alcohol which was converted to the corresponding triflate for A-alkylation with 4-vinyl-oxyazetidin-2-one. A Lewis acid catalyzed ring closure released 1-oxa-cephams from the support. 

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