Picolinyl group as an efficient alcohol protecting group: cleavage with Zn(OAc)2·2H2O under a neutral condition
摘要:
As an efficient alcohol protecting group, picolinates (Pic), prepared from the corresponding alcohols using commercial picolinoyl chloride, are readily cleaved by Zn(OAc)(2) or Cu(OAc)(2), even in the presence of other common alcohol protecting groups. Moreover, the picolinyl group at C-2 position in carbohydrates can be selectively cleaved to give methyl 4,6-O-benzylidene-3-O-picolinyl-alpha-D-glucopyranoside and 3-O-picolinyl methyl-4,6-O-benzylidene-alpha-D-galactopyranoside in good yields. (c) 2005 Elsevier Ltd. All rights reserved.
Spontaneous formation of PMB esters using 4-methoxybenzyl-2,2,2-trichloroacetimidate
作者:Jigisha P. Shah、Christopher M. Russo、Kyle T. Howard、John D. Chisholm
DOI:10.1016/j.tetlet.2014.01.097
日期:2014.3
Carboxylic acids are converted to the corresponding 4-methoxybenzyl (PMB) esters with 4-methoxybenzyl-2,2,2-trichloroacetimidate in the absence of an acid catalyst. This operationally simple procedure is a highly effective method for the formation of PMB esters. The reaction is promoted by the carboxylic acids themselves in excellent yields (72–99%). Sterically hindered carboxylic acids, which provide
Ester Formation via Symbiotic Activation Utilizing Trichloroacetimidate Electrophiles
作者:Nivedita S. Mahajani、Rowan I. L. Meador、Tomas J. Smith、Sarah E. Canarelli、Arijit A. Adhikari、Jigisha P. Shah、Christopher M. Russo、Daniel R. Wallach、Kyle T. Howard、Alexandra M. Millimaci、John D. Chisholm
DOI:10.1021/acs.joc.9b00745
日期:2019.6.21
Trichloroacetimidates are useful reagents for the synthesis of esters under mild conditions that do not require an exogenous promoter. These conditions avoid the undesired decomposition of substrates with sensitive functional groups that are often observed with the use of strong Lewis or Brønsted acids. With heating, these reactions have been extended to benzyl esters without electron-donating groups. These inexpensive