H-Dap(Boc)-OMe HCl

H-Dap(Boc)-OMe HCl
Nβ-Boc-L-2,3-diaminopropionic acid methyl ester hydrochloride; methyl (2S)-2-amino-3-[(2-methylpropan-2-yl)oxycarbonylamino]propanoate hydrochloride

Three things are true of this compound at once: the backbone α-amine is free, as its hydrochloride; the side-chain β-amine carries Boc; and the α-carboxyl is a methyl ester. Note which nitrogen is which — the protected one is the side-chain nitrogen, the reverse of the solid-phase building blocks, where the α-amine is the one that carries the protecting group. With the carboxyl esterified and the α-amine free, this is the amine component of a solution-phase coupling rather than a stepwise solid-phase building block: the ester keeps the carboxyl out of the reaction while the α-amine is acylated.

The methyl ester is not an acid-labile group. TFA removes the Boc from the β-nitrogen and leaves the ester in place, so one acid treatment does not unmask both: the free acid is produced by hydrolysis or saponification, a separate step with its own conditions, rather than by acidolysis.

Weigh it as the salt: the hydrochloride is C9H19ClN2O4, 254.71, against 218.25 for the free base, so the salt's mass is the one to calculate with. As an amine hydrochloride it also needs an extra equivalent of base wherever the reaction wants the free amine, before the acylation.

The solid-phase-ready derivatives of the same amino acid are separate listings: Fmoc-Dap(Boc)-OH (47061), Fmoc-Dap(Mtt)-OH (47250) and Boc-Dap(Fmoc)-OH (47251).

Applications

• Solution-phase coupling in which the diaminopropionate supplies the amine component
• Preparation of other 2,3-diaminopropionic acid derivatives and dipeptide esters
• Routes that need the carboxyl masked through an acidolytic step

Storage
Store refrigerated (2–8 °C) in a tightly closed container, and let it reach room temperature before opening.

For research use only. Not for human or veterinary use.