Pyrrole Studies; 34¹. Synthesis of 1,2-Di(2-pyrrolyl)ethenes and Related Compounds

Synthesis of the Spiroiminal Moiety and Approaches to the Synthesis of Marineosins A and B

“…The suspension of magnesium in THF was slowly treated with 4-bromo-1-pentene (1.64 g, 11.0 mmol) and was heated to reflux gently. The resulting solution was refluxed for 2 h, cooled to 25 °C and cannulated to a solution of 1-(phenylsulfonyl)-2-pyrrolecarboxaldehyde 43 (1.95 g, 8.25 mmol) in THF (15 mL) at 0 °C. The mixture was then stirred at 25 °C for 3 h and was quenched with 0.5 M HCl (8 mL).…”

Probing the hydrolytic reactivity of 2-difluoromethyl pyrroles

“…Solutions of air-and moisture-sensitive compounds were introduced via syringe or cannula through a rubber septum. Compounds 4, 45 9, 46 and 15 47 were prepared according to literature procedures.…”

Aminomethylated Pyrroles: Casting a Spotlight

“…Triphenylphosphine acts as a strong nucleophile which displaces the quaternized dialkylamino group from pyrrole Mannich bases to yield (pyrrol-2-ylmethyl)triphenylphosphonium iodides (67) [86,87], useful as starting materials in Wittig reactions with aromatic aldehydes [19]. The same approach led to the 1,2-dipyrryl substituted alkene (68) precursor in a photochemical cyclization-based strategy allowing the rapid construction of the skeleton of the Streptomyces metabolites PDE-I and PDE-II (Scheme 19) [88].…”

“…The same approach led to the 1,2-dipyrryl substituted alkene (68) precursor in a photochemical cyclization-based strategy allowing the rapid construction of the skeleton of the Streptomyces metabolites PDE-I and PDE-II (Scheme 19) [88]. Sodium diethylphosphite is yet another example of phosphorous-containing nucleophile able to react with pyrrole Mannich bases [87].…”

“…Pyrrole Mannich bases derived from less reactive substrates did not undergo the deaminomethylation under these conditions. Treatment of the Mannich bases with para-toluenesulfonyl chloride afforded the expected sulfonamides (86), whereas the addition to isocyanates, isothiocyanates, and acrylamide gave ureas (87), thioureas (88), and β-aminoacrylamide (89), respectively. Acylation of these compounds with both acid chlorides and anhydrides led to N,N-disubstituted amides (84), which could be in turn reduced to the corresponding tertiary amines (85) (Scheme 24).…”