Deallyloxy- and debenzyloxycarbonylation of protected alcohols, amines and thiols via a naphthalene-catalysed lithiation reaction

Deacylation of Esters, Thioesters and Amides by a Naphthalene-Catalysed Lithiation

“…In general, the deprotection of pivaloyl bearing substrates gave the expected products in good yields, except those in which the R substituent was cyclohexyl ( 15), probably due to the participation of the generated lithium amide as a base in b-elimination processes.…”

“…Finally, both pivalamides 1m-p and the benzamide 1q under the aforementioned reductive deprotection conditions furnished deacylated amines 2m-p, generally in good yields (Equation 1 and Table 1, entries [13][14][15][16][17]. The reductive removal of the pivaloyl group of N-octylpivalamide was also attempted following the same procedure previously used by us in the deprotection of tritylated primary amines, 13 (deprotonation with n-butyllithium and treatment with trimethylsilyl chloride before performing the lithiation step) however, the reaction failed in this case, the starting amide being quantitatively recovered.…”

“…8-10 Among other uses, 11 this methodology has been shown to be applicable to the cleavage of trityl ethers 12 and amines, 13 for the desilylation of silylated alcohols, amines and thiols, 14 as well as for the deprotection of allyloxy-or benzyloxycarbonyl-protected alcohols, amines and thiols. 15 In this paper we wish to report on the use of a naphthalenecatalysed lithiation to perform the deacylation of representative esters, thioesters and amides under very mild non-hydrolytic conditions. The reaction of different alkyl or aryl pivalates 1a-e with an excess of lithium (1:9 molar ratio) and a catalytic amount of naphthalene (1:0.16 molar ratio) in THF at 0 °C for two to four hours led, after quenching with methanol, to the corresponding alcohols 2a-d and phenol 2e (Equation 1 and Table 1, entries 1-5).…”

3-(2-Aminophenyl)-4-methyl-1,3-thiazole-2(3H)-thione as an Ecofriendly Sulphur Transfer Agent to Prepare Alkanethiols in High Yield and High Purity

“…Moreover, it must be stressed that thiols easily undergo oxidation to disulphides under ambient conditions. Protecting groups are thus used to grant long term stability to derivatives, implying development of protection-deprotection procedures [ 16 , 17 , 18 , 19 , 20 ] with consequent loss of yield.…”

Reductive removal of the Boc protecting group via a DTBB-catalysed lithiation reaction

“…11,12,13 Among other uses, 14 this methodology has been shown to be applicable to the cleavage of trityl ethers 15 and amines, 16 to the desilylation 17 and the deallyloxy-or debenzyloxycarbonylation 18 of protected alcohols, amines and thiols, and to perform the deacylation of esters, thioesters and amides. 19 In this paper we report on the reductive removal of the Boc group from protected alcohols, amines and thiols via a DTBB-catalysed lithiation process under very mild reaction conditions.…”