“…The acids 172 are then converted into Weinreb-type amides 173 . , This has been carried out for 173a , b , d , and e in yields of 53−72%. The formation of amide 173b was optimized (92% yield) by choosing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the activator in the presence of Hünigs base in DMF instead of the usual DCC/Et 3 N . The amides were then reacted with Grignard or organolithium reagents at −30 to −40 °C. ,, Under these conditions, there is no erosion of configurational integrity of the ketones (at −10 to 0 °C, 5−10% racemization may occur). , …”
Section: Nn-dibenzylamino Ketonesmentioning
confidence: 99%
“…The formation of amide 173b was optimized (92% yield) by choosing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the activator in the presence of Hu ¨nigs base in DMF instead of the usual DCC/Et 3 N. 138 The amides were then reacted with Grignard or organolithium reagents at -30 to -40 °C. 22,134,138 Under these conditions, there is no erosion of configurational integrity of the ketones (at -10 to 0 °C, 5-10% racemization may occur). 22,134 Some of the compounds were also prepared by application of the Gilman-Jorgenson ketone synthesis (11b, v, w) 22,134,139,140 or the Mukaiyama one-pot ketone preparation based on the use of anhydrides 174 ( 11a, b, c, k, l, x).…”
“…The acids 172 are then converted into Weinreb-type amides 173 . , This has been carried out for 173a , b , d , and e in yields of 53−72%. The formation of amide 173b was optimized (92% yield) by choosing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the activator in the presence of Hünigs base in DMF instead of the usual DCC/Et 3 N . The amides were then reacted with Grignard or organolithium reagents at −30 to −40 °C. ,, Under these conditions, there is no erosion of configurational integrity of the ketones (at −10 to 0 °C, 5−10% racemization may occur). , …”
Section: Nn-dibenzylamino Ketonesmentioning
confidence: 99%
“…The formation of amide 173b was optimized (92% yield) by choosing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the activator in the presence of Hu ¨nigs base in DMF instead of the usual DCC/Et 3 N. 138 The amides were then reacted with Grignard or organolithium reagents at -30 to -40 °C. 22,134,138 Under these conditions, there is no erosion of configurational integrity of the ketones (at -10 to 0 °C, 5-10% racemization may occur). 22,134 Some of the compounds were also prepared by application of the Gilman-Jorgenson ketone synthesis (11b, v, w) 22,134,139,140 or the Mukaiyama one-pot ketone preparation based on the use of anhydrides 174 ( 11a, b, c, k, l, x).…”
“…Based on steric arguments, the conformer shown should be preferred. [14] Consequently, the hydride is delivered from the least hindered (Si) face resulting in the formation of 2 b as the major isomer.…”
We report here a concise route to synthesize various stereoisomers of tetrahydrofuran amino acids (TAAs) and the synthesis of TAA‐containing linear cationic dodecapeptides. Some of these linear peptides show slightly better antimicrobial activities than their tetra‐ and octameric congeners, but no activity against Mycobacterium tuberculosis, for which octapeptides exhibited by far the best results; this implies that antibacterial activity is dependent on the length of these linear peptides. All the dodecapeptides described here were found to be toxic in nature against Vero cells. The study helps to delineate the optimal length of this series of linear peptides and select potential leads in the development of novel cationic peptide‐based antibiotics.
“…However, the use of LTA would obviously present a major issue for the large-scale application unless alternative reagents could be found. It was mentioned in the paper that compound 148 can also be prepared using a chiral-pool approach in three steps from l -valine …”
Section: 42 Addition To Other Electrophilesmentioning
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