“…Despite the very hindered nature of the 14 position, cultures UC 5059, UC 11141, and UC 11144 were able to introduce the hydroxyl group at this position to give 8 (10-15% yield). The structure proofs for these three compounds (6)(7)(8) hydroxylated at positions 16, 15, and 14 rests again on the deshielding effect of the hydroxyl group in the NMR spectrum as described above. Compounds 6-8 were also identical with samples prepared from 1 by multistep synthetic procedures, 16 and the stereochemistries of these compounds were previously assigned.…”
Section: Resultsmentioning
confidence: 96%
“…Expansion of the anthelmintic arsenal is thus an urgent goal. Marcfortine A, paraherquamide A, and their analogues have potent antiparasitic activity. − Because the marcfortines and paraherquamides are unique both structurally and in their mode of action, they represent a promising new class of anthelmintics (Figure ). 1 t…”
Hydroxylation of the indole alkaloid marcfortine A (1)
at carbon atoms 5, 10, 12, 14, 15, 16,
and 27 was realized by various soil-derived microorganisms.
Fission at the C-12−N bond was
also observed. The structural elucidation of the products
(2
−
12) was accomplished
by
spectroscopic and semisynthetic means.
“…Despite the very hindered nature of the 14 position, cultures UC 5059, UC 11141, and UC 11144 were able to introduce the hydroxyl group at this position to give 8 (10-15% yield). The structure proofs for these three compounds (6)(7)(8) hydroxylated at positions 16, 15, and 14 rests again on the deshielding effect of the hydroxyl group in the NMR spectrum as described above. Compounds 6-8 were also identical with samples prepared from 1 by multistep synthetic procedures, 16 and the stereochemistries of these compounds were previously assigned.…”
Section: Resultsmentioning
confidence: 96%
“…Expansion of the anthelmintic arsenal is thus an urgent goal. Marcfortine A, paraherquamide A, and their analogues have potent antiparasitic activity. − Because the marcfortines and paraherquamides are unique both structurally and in their mode of action, they represent a promising new class of anthelmintics (Figure ). 1 t…”
Hydroxylation of the indole alkaloid marcfortine A (1)
at carbon atoms 5, 10, 12, 14, 15, 16,
and 27 was realized by various soil-derived microorganisms.
Fission at the C-12−N bond was
also observed. The structural elucidation of the products
(2
−
12) was accomplished
by
spectroscopic and semisynthetic means.
“…The synthetic pathway employed for the preparation of macrolactam 2 is illustrated in Scheme 1. Bis-silylated AVM 5 was subjected to Seebach transesterification with Ti(OiPr) 4 in β-(trimethylsilyl)ethanol to generate secoester 6 . The specific reaction conditions employed were those described by Julia et al .…”
The first synthesis of 1,19-aza-1,19-desoxy-avermectin B(1a) (2) is described. This new macrolactam, prepared efficiently from avermectin B(1a) (1a) in seven steps, was designed to form an intramolecular hydrogen bond between the amide carbonyl and the adjacent C7 tertiary hydroxyl via a six-center hydrogen bonding network. The presence of this intramolecular hydrogen bond is anticipated to confer additional conformational rigidity to the 16-membered macrocycle.
“…Expansion of the anthelmintic arsenal is thus an urgent goal. Marcfortine A, paraherquamide A, and their analogs have potent antiparasitic activity . Because the marcfortines and paraherquamides are unique both structurally and in their mode of action, they represent a promising new class of anthelmintics.…”
mentioning
confidence: 99%
“…The stereochemistry of 10 was established by comparison of its 1 H NMR spectrum with that reported by Blizzard et al. in their synthesis of 10 by an alternate synthetic route 3a…”
The paraherquamides and marcfortines represent a novel class of anthelmintics. The sole structural difference between paraherquamide A and marcfortine A occurs in ring G. We synthesized paraherquamide B from marcfortine A in six steps. Paraherquamide A was then prepared from paraherquamide B in seven steps. This represents the first formal synthesis of paraherquamide A.
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