dipyrromethane - one-pot synthesis
High purity dipyrromethane is essential for its applicationin the synthesis of asymmetric -substituted porphyrin.
Technibel | Unsubstituted dipyrromethane synthesis essay
AB - A variant of the MacDonald approach was devised for the synthesis of porphyrins. A new base-catalyzed one-step synthesis of 1,9-dipyrromethane- dicarbinols was achieved by Friedel-Crafts alkylation of dipyrromethanes using commercially available ethyl glyoxylate solution in toluene. This method avoids the use of acid chlorides, Grignard reagents, borohydride reductions, and acidic conditions. The [2 + 2] condensation of dipyrromethanedicarbinols and dipyrromethanes yielded 5,15-di(ethoxycarbonyl)porphyrins.
A series of novel meso-(8-substituted naphth-1-yl)porphyrins has been synthesized creating derivatives with a tight recognition environment above the porphyrin plane. The selective synthesis of single atropisomers is discussed. Condensation of bisnaphthaldehyde 12 with phenyldipyrromethane unexpectedly led to selective synthesis of the alpha,alpha-5,10-bridged isomer 14. A mechanism is proposed for this unusual scrambling, and alternative syntheses of alpha,alpha-5,15-bisnaphthylporphyrins are described. Synthesis of 5,15-analogues can be achieved by employing (pentafluorophenyl)dipyrromethane or via presynthesis of a bis(dipyrromethane) derivative 22 (from bisnaphthaldehyde 12) and subsequent condensation with benzaldehyde.
Unsubstituted dipyrromethane synthesis essay - …
A porphyrin bearing a formyl and an ester group at trans-meso positions was synthesized from a 1,9-diacyl-5-acetaldipyrromethane and an ester-dipyrromethane (). The direct diacylation of the acetal-dipyrromethane 1g with EtMgBr and p-toluoyl chloride was not successful. We then tried to introduce the two 4-methylbenzoyl substituents in separate steps. Following known procedures,,, reaction of dipyrromethane 1g with EtMgBr followed by Mukaiyama reagent 5b gave the crude 1-p-toluoyl-5-(5,5-dimethyl-1,3-dioxan-2-yl)dipyrromethane, which upon dialkylboron complexation with Bu2B-OTf gave the boron complex 12-BBu2 in 34% yield. The boron complex 12-BBu2 was treated with MesMgBr and p-toluoyl chloride to form the 1,9-diacyldipyrromethane 13-BBu2 in 56% yield. The latter was reduced by NaBH4 and the resulting dipyrromethane-1,9-dicarbinol was condensed with ester-dipyrromethane 1e to afford acetal/ester-porphyrin H2P9-acetal. A small amount (~1%) of aldehyde-porphyrin (from deprotection of H2P9-acetal) was also observed in the reaction mixture by LD-MS. The purified acetal/ester-porphyrin H2P9-acetal was obtained in 14% yield. Treatment of H2P9-acetal in the biphasic mixture of CH2Cl2 and TFA/H2O, gave the aldehyde/ester-porphyrin H2P9-CHO in 85% yield.
The synthesis of ZnP8-OH entailed the acylation of dipyrromethane 1a (). Treatment of 1a with EtMgBr and benzoyl chloride followed by tin complexation with Bu2SnCl2 yielded tin complex 11-SnBu2 in 63% yield. The latter was then reduced by NaBH4. The resulting dipyrromethane-1,9-dicarbinol was condensed with ester-dipyrromethane 1e in the presence of InCl3 followed by oxidation with DDQ to afford the free base porphyrin H2P8-OTBDMS in 27% yield. Metalation gave zinc porphyrin ZnP7-OTBDMS in 95% yield, and deprotection with TBAF yielded ZnP7-OH in 71% yield.
Synthesis If Dipyrromethane And Their Pollymerization
Three trans-AB2C-porphyrins with different patterns of one-carbon substitution were synthesized following literature procedures for the condensation of a dipyrromethane-1,9-dicarbinol and a dipyrromethane., A porphyrin with one hydroxymethyl and three aryl groups was first synthesized. Tin complex 10-SnBu2 was reduced by NaBH4. The resulting dipyrromethane-1,9-dicarbinol was condensed with TBDMS-protected hydroxymethyldipyrromethane 1a to afford free base porphyrin H2P7-OTBDMS in 12% yield (). Treatment of H2P7-OTBDMS with Zn(OAc)2·2H2O afforded ZnP7-OTBDMS in 95% yield. The TBDMS group of H2P7-OTBDMS and ZnP7-OTBDMS was removed by treatment with TBAF to yield H2P7-OH and ZnP7-OH in 60% and 81% yield, respectively. The synthesis of H2P7-OH and ZnP7-OH was previously carried out with the unprotected 5-hydroxymethyldipyrromethane. Although the yields are comparable in the two routes, the presence of a protecting group opens access to synthetic routes that are not possible with the free hydroxy group. An example is provided for porphyrins bearing two different one-carbon groups, such as ZnP8-OH, which bears one hydroxymethyl group and one ester group at opposite meso positions.
Thus, 1,9-bis(N,N-dimethylaminomethyl)dipyrromethanes were synthesized from the corresponding dipyrromethanes (1b, 1e and 1f) by treatment with Eschenmoser’s reagent. The resulting crude products were used in the porphyrin syntheses without further purification. The condensation reaction was performed in refluxing ethanol containing Zn(OAc)2 followed by oxidation with DDQ. Zinc porphyrins ZnP4-OTBDMS, ZnP5-OTBDMS and ZnP6-OTBDMS were purified by chromatography and obtained in pure form but in low yield. The zinc porphyrins were then treated with TBAF to remove the TBDMS group, affording hydroxymethylporphyrins ZnP4-OH, ZnP5-OH and ZnP6-OH. Porphyrin ZnP6-OH contains a free hydroxymethyl group and an ethynyl group owing to removal of both the TBDMS and TMS groups, respectively. The molecule ion of ZnP6-OH was observed by LD-MS with POPOP as the matrix. Similar to ZnP1-(OH)4, high-resolution mass measurements for ZnP6-OH were not successful.
Unsubstituted dipyrromethane synthesis essay
ERIC - Synthesis of "Meso"-Diethyl-2,2'-Dipyrromethane …
In this communication we describe the first results of an efficient synthesis of β-free-dipyrromethanes in water
Color Control in π-Conjugated Organic Polymers for Use …
21/03/2017 · Porphyrin Bootcamp 2017: #1 Dipyrromethane Synthesis - Duration: 2:44
Reynolds at the University of Florida in Gainesville
dipyrromethane is a pyrrole building block for the synthesis of porphyrins
Heme Metabolism | Biosynthesis | Red Blood Cell
A trans-A2-porphyrin was synthesized in a similar manner. The self-condensation of the carbinol derived from 1-acyldipyrromethane 9 was catalyzed by Yb(OTf)3 instead of InCl3. The protected bis(hydroxymethyl)porphyrin H2P3-(OTBDMS)2 was obtained in 7.5% yield. Deprotection with TBAF afforded the trans-A2-porphyrin H2P3-(OH)2 in 66% yield. Similar to ZnP1-(OH)4, H2P3-(OH)2 also showed poor solubility and was purified by washing with water, acetone and THF.
Synthesis of Porphyrin-C 60 Dyads with Potential Use in Solar Cells
Trans-A2-porphyrins or A2B2-porphyrins can be synthesized by the condensation of a dipyrromethane and an aldehyde. However, alkyl-substituted dipyrromethanes are somewhat susceptible to scrambling.- An alternative synthetic route to a trans-A2- or A2B2-porphyrin is via a 1-acyldipyrromethane. Two 1-acyldipyrromethanes bearing one hydroxymethyl moiety were obtained from the corresponding dipyrromethanes in a manner similar to that of the synthesis for H2P1-(OTBDMS)4. 5-Mesityldipyrromethane (1c) or unsubstituted dipyrromethane (1d) reacted with EtMgBr and pyridyl thioester 5a to afford TBDMS-protected 1-acyldipyrromethane 8 or 9 in 74% or 85% yield, respectively (). 1-Acyl-5-mesityldipyrromethane 8 was reduced by NaBH4 and the resulting dipyrromethane-1-carbinol was self-condensed,, in the presence of InCl3 followed by oxidation with DDQ to afford TBDMS-protected bis(hydroxymethyl)porphyrin H2P2-(OTBDMS)2 in 13% yield (). Cleavage of the TBDMS group by TBAF afforded porphyrin H2P2-(OH)2 quantitatively.
Thieme E-Journals - Synlett / Abstract
Mukaiyama reagents (S-2-pyridyl thioacyl compounds) are valuable species in porphyrin synthesis. The acylation of a dipyrromethane with a Mukaiyama reagent selectively introduces the desired acyl group at the 1-position of the dipyrromethane. An attempt to synthesize S-2-pyridyl hydroxythioacetate without TBDMS protection was not successful. The synthesis of TBDMS-protected glycolic acid 4 from glycolic acid and TBDMSCl has been reported but with limited data. However, in our hands the yield of the reaction varied and sometimes was lower than 10%. Alternatively, ethyl glycolate was treated with TBDMSCl to afford the TBDMS-protected glycolate (). Without purification, the ester was hydrolyzed to afford TBDMS-protected glycolic acid 4 in 55% yield, a known compound with limited characterization data., Reaction of 4 with 2,2′-dipyridyl disulfide gave the corresponding pyridyl thioester 5a in 43% yield.
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