General Method for Selective Mono-Boc Protection of Diamines and Thereof

Abstract

Here we report a simple and efficient protocol for selectively diamine protection with Boc using Me<sub>3</sub>SiCl or SOCl<sub>2</sub> as HCl source in “one-pot” procedure. This methodology is extended to 1,2- to 1,8-diamines to obtain the corresponding mono-Boc protected diamines.

trans- and cis-DACH-Based Bifunctional Squaramides Catalyzed Ring-Opening Polymerizations of Asymmetric Substituted Glycolides

“…trans -DACH-based bifunctional catalysts were synthesized with five-step reactions in high yields ranging from 69% up to 100% in each reaction and from 32 to 39% in overall yields (Scheme B): (i) the removal of tartrate from diaminocyclohexane mono-(+)-tartrate 12 in a basic medium to obtain compound 13 having free amine groups at room temperature in 83% yield; (ii) the conversion of one of the free amines in compound 13 to the Boc-protected amine in compound 14 ,, as a consequence of the reaction of the compound 13 with di- tert -butyl dicarbonate (Boc 2 O) in the presence of HCl in methanol; (iii) the formation of a pyrrolidine or piperidine ring as shown in compounds 15 and 16 from the free amine group in the mono Boc-protected compound 14 in the presence of 1,4-diiodobutane or 1,5-dibromopentane in a basic medium, respectively; (iv) the removal of the Boc-protected group from compounds 15 and 16 in the presence of trifluoroacetic acid to yield products 17 , and 18; and (v) the coupling of intermediates 7 – 11 with deprotected compounds 17 or 18 to give the organocatalysts 19 – 25 . ,,,, …”

“…trans-DACH-based bifunctional catalysts were synthesized with five-step reactions in high yields ranging from 69% up to 100% in each reaction and from 32 to 39% in overall yields (Scheme 1B): (i) the removal of tartrate from diaminocyclohexane mono-(+)-tartrate 12 in a basic medium to obtain compound 13 16 having free amine groups at room temperature in 83% yield; (ii) the conversion of one of the free amines in compound 13 to the Boc-protected amine in compound 14 21,56,57 as a consequence of the reaction of the compound 13 with di-tert-butyl dicarbonate (Boc 2 O) in the presence of HCl in methanol; (iii) the formation of a pyrrolidine or piperidine ring as shown in compounds 15 58 and 16 21 from the free amine group in the mono Boc-protected compound 14 in the presence of 1,4-diiodobutane or 1,5-dibromopentane in a basic medium, respectively; (iv) the removal of the Boc-protected group from compounds 15 and 16 in the presence of trifluoroacetic acid to yield products 17 58,59 and 18; 21 and (v) the coupling of intermediates 7−11 with deprotected compounds 17 or 18 to give the organocatalysts 19− 25. 15,16,21,60,61 cis-DACH-based bifunctional catalysts were synthesized by the four-step reaction sequence providing yields mostly higher than 70% in each step and with overall yields ranging from 32 to 45%, as indicated in Scheme 1C: (i) desymmetrization of cis-DACH 26 with diallyl carbonate in toluene by CAL-B to yield product 27, 21,62 (ii) formation of compounds 28 and 29 having a pyrrolidine or piperidine ring as the tertiary amine structure via cyclization of 1,4-diiodobutane or 1,5-dibromopentane with compound 27 in the presence of K 2 CO 3 in acetonitrile, 21 (iii) deprotection of the mono-N-allyloxycarbonyl (alloc) group from 28 and 29 with the palladium diacetate catalyst in the presence of 1,3-dimethylbarbituric acid as an allyl scavenger to give the products 30 or 31, 21 and (iv) coupling of intermediates 7−11 with the deprotected compound 30 or 31 to acquire the organocatalysts 32−37.…”

Synthesis of New Amino—β-Cyclodextrin Polymer, Cross-Linked with Pyromellitic Dianhydride and Their Use for the Synthesis of Polymeric Cyclodextrin Based Nanoparticles

“…There was a need to protect the reactive functional group -NH 2 , with a protective group. Used for this a tert -butyloxycarbonyl group (BOC) [ 23 , 24 , 25 ]. The β-CD-NH 2, was polymerized using crosslinking reaction [ 26 , 27 , 28 ].…”