A convenient approach for the deprotection and scavenging of the PMB group using POCl3

Abstract

A convenient and high yielding approach for the deprotection and scavenging of the p-methoxybenzyl (PMB) group in PMB ethers and PMB esters was developed using POCl 3 as the reagent. 4-Methoxybenzyl chloride, a starting material used for the preparation of PMB ethers and esters was regenerated in the deprotection step. This mild and selective procedure tolerates several acid sensitive functional groups.

Total synthesis of (+)-grandiamide D, dasyclamide and gigantamide A from a Baylis–Hillman adduct: A unified biomimetic approach

“…Among different reagents such as DDQ, CAN, Yb(OTf) 3 and CeCl 3 –NaI used for deprotection of the PMB group, TFA gave the better result. Even though POCl 3 [ 14 ] was able to effect complete removal of the PMB group in short time, the yield was only moderate. Thus (±)-grandiamide D ((±)- 5 ) was obtained in 16.6% overall yield.…”

Preparation and Applications of 4-Methoxybenzyl Esters in Organic Synthesis

“…79 These conditions were also found to be effective in the deprotection of PMB ethers but did not affect benzyl ethers or acid-sensitive Boc -carbamates. For example, the tyrosine-based PMB ester 84 was deprotected to the carboxylic acid 85 in 82% yield under these conditions.…”

A mild and efficient method for the selective cleavage of primary p-methoxybenzyl protecting group of saccharides by Co2(CO)8–Me2PhSiH–CO system

“…1 Various methods have been developed to cleave PMB ether. 2,3 Recent advances include selective catalytic hydrogenolysis, 4 oxidative cleavage, 5 and the use of new Lewis acids such as AgSbF 6 and POCl 3 . 3,6,7 Some other studies also focus on transforming PMB to other functional groups directly.…”

“…2,3 Recent advances include selective catalytic hydrogenolysis, 4 oxidative cleavage, 5 and the use of new Lewis acids such as AgSbF 6 and POCl 3 . 3,6,7 Some other studies also focus on transforming PMB to other functional groups directly. 8 However, few protecting groups are stable under Lewis acid or oxidative conditions, especially in carbohydrate manipulations, and groups like thiol can greatly inhibit the reaction process during Pd catalyzed reaction.…”