tert-Butyl 14-(tosyloxy)-3,6,9,12-tetraoxatetradecan-1-oate

tert-Butyl 14-(tosyloxy)-3,6,9,12-tetraoxatetradecan-1-oate, is designed to provide a polar, flexible poly(ethylene glycol)-like spacer while presenting a tosylate leaving group for efficient nucleophilic substitution. Its ether-rich backbone supports solubility and conformational adaptability in targeted protein degradation constructs. The combination of a protected terminus and an activated electrophile makes it a practical intermediate for assembling PROTACs, with detailed structural and synthetic considerations provided below.

Structure: The linker contains a tetraoxa polyether chain featuring multiple ether oxygen atoms, a terminal tert-butyl ester functionality, and a tosylate-activated alcohol at the opposite terminus. It incorporates aromatic sulfonate bonding within the tosyl group and stable C–O and C–C linkages, yielding a polar, ether-rich scaffold.

Reactivity: The tosylate terminus is suitable for substitution via nucleophilic substitution mechanisms, enabling attachment of PROTAC warheads or handles under standard alkylation conditions. Reactions are typically performed with nucleophiles such as amines or thiols in polar aprotic solvents, often using mild bases to promote nucleophile formation. The tosylate serves as an excellent leaving group, facilitating efficient coupling without requiring transition-metal catalysis.