A Dipyrromethane

A simple and versatile one-pot synthesis of meso-substituted trans-A2B-corroles (Scheme 7) was reported by Gryko and Jadach (01JOC4267). It affords regioisomerically pure frans-A2B-corroles 11 through the TFA-catalyzed condensation of a dipyrromethane 10 and an aldehyde followed by oxidation with DDQ. The synthesis is compatible with diverse functionalities ester, nitrile, ether, fluoro, hydroxy, etc. on the aryl group of the... 

The 21,22-dioxaporphyrin 227 was synthesized by "2+2" acid-catalyzed condensation of 5,5 -diformyldifurrylmethane and a dipyrromethane diacid (1969JCS(CC)1480). 21,22-Diheteroporphyrins 229 (X=Y=0, S X=S, Y=0) containing S and O atoms have been obtained from 228 (X=Y=0 X=Y=S and X=S, Y=0) with 5-phenyl dipyrromethane derivative, followed by oxidation with DDQ (1998BKCS314,1999TL8879). 

Figure 4.7 (a) interaction of a dipyrromethane-based cofactor in porphobilinogen deaminase with... 

Another Ptn molecule where the acetylide unit governs the photophysics of the metal complex has recently emerged. In this report the Ptn contained an appended phenylacetylide that was substituted in the para position with a dipyrromethane-BF2 (BODIPY) subunit, 3.9 [64],... 

With the original reports of the successM synthe of the sapphyrins [26,66,152] and uranyl superphthalocyanine [112, 118, 119], interest in other expanded porphyrin systems, was kindled. The next logical step (after sapphyrin), in the expanding series of all-pyrrole systems, was the pentaphyrin macrocycle 231 which contains five pyrroles and five meso-like methine bridgra. In 1983 Gossauer et al. reported the synthesis of the first prototypical member 231 of this macrocyclic family [158, 182, 183, 185-187]. This first synthesis was achieved by a 2 + 3 MacDonald-type condensation between an oc-firee dipyrromethane 233 and a tripyrrane dialdehyde 236. More recently, the synthesis of pentaphyrin 231 has l n achieve by using a dipyrromethane 5,5 -dicarboxylic acid 235 in place of an a-firee dipyrromethane [21]. Here, as is the case in many of these kind of reactions [21,26,27,66,155], decarboxylation occurs under the reaction conditions to produce the corresponding a-free species 233 in situ. (Scheme 40) [21]. 

Using an approach similar to that described in the preceding paragraph, this methodology enables the synthesis of 5,15-diaryl- or 5,15-dialkyl-porphyrins from a dipyrromethane and an alkyl- or arylaldehyde linker molecule.36 In the example shown, porphyrin (73) can be obtained from the 5-mesityldipyrromethane (74) (prepared in a manner similar to that described for (64)) and 4-iodobenzaldehyde if the dipyrromethane (74) had been unsubstituted at the 5-position, a 5,15-diarylporphyrin would have resulted (Scheme 22). Mixed 5-alkyl-15-arylporphyrins, such as (75), can be prepared35,46 by treatment of 1,9-di-unsubstituted 5-alkyldipyrromethanes (e.g., (76)) with l,9-diformyl-5-aryldipyrromethanes (77) in a MacDonald-type [2 + 2] approach (Scheme 23). 

The presence of an a-free pyrrole attached to the native HMBS was also demonstrated, both in Cambridge and Southampton, by treatment with Ehrlich s reagent, acidic p-dimethylaminobenzaldehyde [30, 33]. This initially gave the UV/visible absorbance at 564 nm, typical of the Ehrlich product from an a-free pyrrole, but the spectrum then changed to one at 495 nm, typical of a dipyrromethene, indicating that the cofactor is in fact a dipyrromethane (e. g. 32), as shown in Scheme 11 and tautomerisation of the initial product 33 occurs to give 34. 

Figure 4.7 (a) interaction of a dipyrromethane-based cofactor in porphobilinogen deaminase with an aspartic acid-derived side chain. The carboxylate residues of the co-factor are stabilised by protein arginine residnes. (b) general strnctnre of the prodigiosins (R, R = alkyl). 

Thiocarbamoylthymidine has been converted into various species with heterocycles joined to thymidine through an ether link. Water-soluble C-linked nucleoside-porphyrins have been made by reaction of 2, 3 -0-iso-propylideneuridine-5 -carboxaldehyde with pyrrole to give a dipyrromethane, which was treated with p-fluorobenzaldehyde to give after oxidation a porphyrin... 

The inverted porphyrins (also called N-confused porphyrins) 289 were discovered accidentally as by-products of the well-known acid-catalyzed pyrrole aldehyde cyclocondensation route to porphyrins (Scheme 58) (see Chapter 14 by Latos-Grazynski). Rational multistep synthetic approaches to inverted porphyrins have t peared recently. Dolphin and coworkers. s have reported a method for the preparation of porphyrin 292 involving acid-catalyzed MacDonald-type (2 -I- 2) condensation of an a,j8-dipyrromethane 291 and a,a-dipyrromethane dialdehyde 290. Lee and coworkers have reported a (3 -I- 1) approach to porphyrin analogues with an inverted pyrrole and a thiphene, or a furan ring system 293 (Scheme 59). Pandey et reported the preparation of dibromo-a, c-... 

Functionalization of the wso-positions has been achieved most conunonly via an acid-catalyzed condensation of a dipyrromethane, containing the group or moiety that is designed to assist in ion binding, with an excess of acetcme [1, 7]. One elegant embodiment of this approach involves so-called strapped calix[4]pyrroles here, a tethered bispyrromethane, the precursor to the strap , is used in the synthesis [8]. 

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