Morpholine, a strong contender for Fmoc removal in solid-phase peptide synthesis.

Morpholine, which scores 7.5 in terms of greenness and is not a regulated substance, could be considered a strong contender for Fmoc removal in solid-phase peptide synthesis (SPPS). Morpholine in dimethylformamide (DMF) (50%-60%) efficiently removes Fmoc in SPPS, minimizes the formation of diketopiperazine, and almost avoids the aspartimide formation. As a proof of concept, somatostatin has been synthesized using 50% morpholine in DMF with the same purity as when using 20% piperidine-DMF.

Serinol-Based Versatile Disulfide-Reducing Reagent.

Here, we report the synthesis of disulfide-reducing agents 2-(dibenzylamino) propane-1,3-dithiol (DPDT) and 2-(dibenzylamino)-2-methylpropane-1,3-dithiol (DMPDT) from serinol and methyl serinol, respectively. DPDT was found to show greater stability than DMPDT. Hence, the effectiveness of DPDT as a reducing agent was evaluated in both liquid and solid phases. The reducing capacity of this agent was comparable to that of DTT.

Breaking a Couple: Disulfide Reducing Agents.

Cysteine is present in a large number of natural and synthetic (bio)molecules. Although the thiol side chain of Cys can be in a free form, in most cases it forms a disulfide bond either with a second Cys (bridge) or with another thiol, as in the case of protecting groups. Efficient reduction of these disulfide bridges is a requirement for many applications of Cys-containing molecules in the fields of chemistry and biochemistry. Here we review reducing methods for disulfide bonds, taking into consideration the solubility of the substrates when selecting the appropriate reducing reagent.

2-(Dibenzylamino)butane-1,4-dithiol (DABDT), a Friendly Disulfide-Reducing Reagent Compatible with a Broad Range of Solvents.

Disulfide-reducing agents play a crucial role in bioconjugate chemistry. Herein, we describe the synthesis of a new disulfide-reducing agent [2-(dibenzylamino)butane-1,4-dithiol (DABDT)] that is conveniently prepared from inexpensive aspartic acid. Being nonmalodorous and highly soluble in a broad range of solvents, DABDT is user-friendly. We have demonstrated its performance both in solution and in the solid phase.