Synthesis of 2-oxazolines and related N-containing heterocycles using [Et2NSF2]BF4 as a cyclodehydration agent

Total Synthesis of Mycobacterium tuberculosis Dideoxymycobactin‐838 and Stereoisomers: Diverse CD1a‐Restricted T Cells Display a Common Hierarchy of Lipopeptide Recognition

“…[3b] Oxazoline acid 11 was prepared from α-methyl- l -serine 5 , by protection as the methyl ester 6 , which was condensed with 2-benzyloxysalicylic acid 8 using COMU to afford amide 9 (Scheme 1a) [7] Cyclization to the oxazoline 10 proceeded smoothly with XtalFluor-M in CH 2 Cl 2 . [8] Saponification of the ester of 10 with LiOH afforded the O -benzyl-protected acid 11 , which was coupled with NH 2 - l -Lys(Boc)OMe using EDC.FICI/FIOAt/DMAP. Saponification of 12 afforded deoxymycobactic acid 13 .…”

The Elusive Seven-Membered Cyclic Imino Ether Tetrahydrooxazepine

“…A suitable monomer was purportedly found in the literature in the form of 2-phenyl-4,5,6,7-tetrahydro-1,3-oxazepine (2-phenyl-2-THOx) 1, the synthesis of which had been described in four independent literature reports using two different methods (Scheme 2). [24][25][26][27][28][29] However, the 2-phenyl-2-THOx 1 prepared according to the literature procedure reported by Mollo et al, 29 did not have the expected physical and chemical properties, based on our experience with 2-oxazolines and 2-DHOx. The obtained product showed a complete lack of any kind of reactivity in CROP, and even any type of alkylation reactivity.…”

“…This apparent hiatus in the literature on CIE CROP may be related to the fact that the synthesis of 2-THOx is also only sparingly reported in the literature, and these compounds are thus not readily available as monomers. [24][25][26][27][28][29] Intrigued by the possibility to introduce a four-carbon linker between the repeating amide units, we set out to investigate the polymerization of such seven-membered CIE monomers. A suitable monomer was purportedly found in the literature in the form of 2-phenyl-4,5,6,7-tetrahydro-1,3-oxazepine (2-phenyl-2-THOx) 1, the synthesis of which had been described in four independent literature reports using two different methods (Scheme 2).…”

An efficient one-pot synthesis of 2-oxazolines with molecular iodine under ultrasound irradiation

“…The reaction of carboxylic acids [12][13][14][15][16][17] or acid derivatives like ester [18][19][20][21][22] with 2-aminoethanol is the most common method for the synthesis of oxazolines. In addition, other substrates such as imidate hydrochlorides [23], N-(2-hydroxyethyl) amides [24][25][26][27][28][29], ortho esters [30], imino ether hydrochlorides [31], aldehydes [32][33][34][35][36][37] and nitriles [38][39][40][41][42][43][44][45][46] have been used to prepare the oxazolines. Despite the potential applications of the reported procedures in the synthesis of 2-oxazoline derivatives, some of them suffered from one or more shortcomings such as prolonged reaction times, expensive catalysts, hazardous reaction conditions, tedious work-up procedures and lack of general applicability.…”