Simple and efficient cleavage reaction of the boc group in heterocyclic compounds

Abstract

Dedicated to the memory of Pr. Ladjama DaifA series of chiral cyclosulfamides have been synthesized by alkaline cyclisation starting from N-benzoylamino acids (Ala, Val, Leu, Phe) derivatives and chlorosulfonyl isocyanate. A simplified and regioselective deprotection of the cyclic compounds (cyclosulfamides) containing the tert-butyloxycarbonyl group (Boc) has been achieved in good yield by fusion under reduced pressure.

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

“…25 Aouf and co-workers have also reported the selective cleavage of N-Boc from N-Boc chiral cyclosulfamides by fusion: mixing N-Boc substrates with catalytic amounts of iodine under reduced pressure. 26 Guillaumet and co-workers have developed the basic deprotection of N-Boc substratesusing sodium carbonate in reuxing DME. 27 Similar basic N-Boc deprotection has been reported by Ewing et al, where sodium tbutoxide in slightly wet tetrahydrofuran was used to cleave off unactivated primary N-Boc from base stable substrates.…”

Synthesis of β-Hydroxy-α,α-difluorosulfonamides from Carbanions of Difluoromethanesulfonamides

“…The residue was purified by reversed-phase chromatography using a Biotage Isolera One Flash purification system including a C-18 reversed-phase preparative Biotage column (30 g) using a gradient of 10–100% methanol over 30 min at 25 mL per minute ( t R = 19 min) to give 27 as a colorless oil (1.88 g, 97% yield). 1 H NMR data of this material was identical to previously reported spectra …”

Sulfamic Acid and Its N- and O-Substituted Derivatives

“…572 Starting from N-benzoylamino acids and chlorosulfonylisocyanate cyclic sulfamides 515 (X = Boc) form, and these can undergo Boc deprotection by fusion under reduced pressure to give 515 (X = H) in 90%+ yields. 1106 Compounds 516 (R = Bn, nBu, Ph, and p-X-C 6 H 4 (X = NO 2 , Br, −CN, etc.) have been synthesized in ∼50% yield from reaction of sulfuryl chloride with 2-chloroethylamine hydrochloride followed by treatment with a primary amine and triethylamine and then ring closure with potassium carbonate in DMSO.…”

“…Rhodium-catalyzed transfer hydrogenation of 2,3-dihydro-[1,2,5]-thiadiazole-1,1-dioxide derivatives gave 514 in excellent yields with % ee ≥ 97 . Starting from N -benzoylamino acids and chlorosulfonylisocyanate cyclic sulfamides 515 (X = Boc) form, and these can undergo Boc deprotection by fusion under reduced pressure to give 515 (X = H) in 90%+ yields …”