The synthesis of a number of 3-alkyl and 3-carboxy substituted pyrroles; their chemical polymerisation onto poly(vinylidene fluoride) membranes, and their use as gas sensitive resistors

Synthetic Studies of Oroidin-derived Pyrrole-imidazole Alkaloids

“…For the synthesis of 2 in chiral form, construction of the chiral aminal moiety at C6 and C10 is the most challenging issue. Romo and co workers reported the rst enantioselective synthesis of ( ) phakellin (19). 4b In their synthesis, hypervalent iodine mediated oxidative cyclization was applied to 17, which is derived from L proline (16), to construct the N,N aminal structure in a highly stereoselective manner (Scheme 3).…”

“…Synthesis of ( ) phakellin (19) by Romo and co workers. nated to give enamine 28 by reaction with methanesulfonyl chloride in the presence of triethylamine in 52% yield from 26.…”

“…Therefore, we examined an alternative strategy to construct the cyclic guanidine 74 from 73 under oxidative conditions via iminium cation, as originally demonstrated by Romo in their synthesis of ( ) phakellin (19) (Schemes 14, 15). 4b For the synthesis of precursor 72 for the oxidative cyclization, we planned to apply intramolecular Friedel Crafts type cyclization of 71 bearing aldehyde and 4 amidepyrrole functional groups.…”

“…Condensation reaction of L prolinol (75) with N Ts protected pyrrole 3 carboxylic acid 76 19 was carried out using EDCI in the presence of DMAP to give amide 77 (92% yield), whose N Ts protective group was converted to N Boc by deprotection with potassium hydroxide in methanol followed by reaction with (Boc) 2 O and triethylamine. 20 Then, the TBS ether was removed with TBAF, and the resulting alcohol was oxidized with IBX to give aldehyde 78 in 65% yield from 77 (4 steps).…”

Thallium Trinitrate (TTN)

“…3 An application of such a rearrangement was the preparation of pyrrole monomers, by using TTN supported on Montmorillonite clay K-10, as recently reported. 5 A convenient application of TTN in organic synthesis is the oxidative rearrangement of olefins. In this fashion, cyclohexene is classically converted into a cyclopentane moiety.…”