Rational Synthesis of Trans-Substituted Porphyrin Building Blocks Containing One Sulfur or Oxygen Atom in Place of Nitrogen at a Designated Site

Cho, Won‐Seob; Kim, † Han-Je; Littler, Benjamin J.; Miller, Mark A.; Lee, Changhee; Lindsey, Jonathan S.

doi:10.1021/jo9909305

Cited by 103 publications

(107 citation statements)

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“…The mono-functionalized heteroporphyrins which are key building blocks for the synthesis of unsymmetrical porphyrin dyads containing heteroporphyrin sub-units were first synthesized by Lee, Lindsey and co-workers 16 as shown in Scheme I. They have used thienylpyrromethane di-carbinol 1 or furylpyrromethane di-carbinol 2 and condensed with functionalized meso-aryl dipyrromethane 3 under mild acid catalyzed porphyrin forming conditions.…”

Section: Mono-functionalized Heteroporphyrin Building Blocksmentioning

confidence: 99%

“…However, the disadvantage of their synthetic approach is the involvement of multi-step synthesis of precursors and their tedious chromatographic purifications. 16 Lee and co-workers 17 used functionalized unsymmetrical tripyrrane 7 and condensed with thiophene 8 or furan di-carbinol 9 under mild porphyrin forming conditions. 26 The condensation resulted in the mixture of three porphyrins: (1) meso-tetra aryl heteroporphyrins (10-11), (2) desired mono-functionalized heteroporphyrins (12-13) and (3) cis di-functionalized heteroporphyrins (14-15) (Scheme II).…”

Section: Mono-functionalized Heteroporphyrin Building Blocksmentioning

confidence: 99%

“…8,9 An assembly of two such different eteroporphyrins (containing cores such as N 3 S, N 3 O, N 2 S 2 , N 2 O 2 , N 2 SO etc) or heteroporphyrin and normal porphyrin (N 4 core) would offer unique dyads which are expected to have unusual electronic structure and interesting properties. Recently, we [10][11][12][13][14][15] and others [16][17] developed novel syn-thetic routes to synthesize mono-functionalized heteroporphyrins which have been used further to synthesize several covalent and non-covalent unsymmetrical porphyrin dyads and higher arrays. In this review, we describe the various synthetic routes developed recently to synthesize monofunctionalized heteroporphyrins and their use in the synthesis of covalently and non-covalently linked unsymmetrical porphyrin dyads containing two different types of porphyrin sub-units.…”

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confidence: 99%

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Mono‐functionalized Heteroporphyrin Building Blocks and Unsymmetrical Covalent and Non‐covalent Porphyrin Dyads

Yedukondalu

Ravikanth

2011

J Chinese Chemical Soc

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Heteroporphyrins resulted from the replacement of one or two pyrrolic nitrogens with other hetero atoms such as O, S, Se and Te possess very interesting and distinct properties compared to tetrapyrrolic porphyrins. Specially, the singlet state energy levels can be fine tuned with suitable modification of porphyrin core by substituting pyrrolic "N" with other hetero atoms such as "O" and "S". In this review, we describe our synthetic approaches for the synthesis of various mono-functionalized heteroporphyrin building blocks and their use in the synthesis of several covalently and non-covalently linked unsymmetrical porphyrin dyads containing two different porphyrin sub-units. The photophysical studies are also described to show the possibility of singlet-singlet energy transfer from one porphyrin sub-unit to another in these unsymmetrical porphyrin dyads.

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Section: Mono-functionalized Heteroporphyrin Building Blocksmentioning

confidence: 99%

Section: Mono-functionalized Heteroporphyrin Building Blocksmentioning

confidence: 99%

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confidence: 99%

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Mono‐functionalized Heteroporphyrin Building Blocks and Unsymmetrical Covalent and Non‐covalent Porphyrin Dyads

Yedukondalu

Ravikanth

2011

J Chinese Chemical Soc

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“…8 (S)-(4-Methylphenyl)-(2'-thienyl)methanol (3f) [14] The title compound was obtained from 2-thiopheneboronic acid (1g) (76.8 mg, 0.6 mmol) and 4-methylbenzaldehyde (2d) (29. …”

Section: (R)-(2-bromophenyl)-(4'-methylphenyl)methanol (Ent-3c)mentioning

confidence: 99%

Diarylmethanols by Catalyzed Asymmetric Aryl Transfer Reactions onto Aldehydes Using Boronic Acids as Aryl Source

2007

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Using a planar-chiral ferrocene as catalyst and combinations of functionalized aldehydes and substituted arylboronic acids as starting materials, asymmetric aryl transfer reactions give access to structurally diverse, optically active diarylmethanols in high yields and enantioselectivities.Keywords: arylboronic acids; C À C bond formation; diarylmethanols; enantioselective catalysis; organozinc reagents Diarylmethanols 3 with defined stereochemistry at the hydroxy-bearing carbon are important intermediates for the synthesis of numerous compounds with high biological and/or physiological activity.[1] For example, neobenodine and orphenandrine show anticholinergic as well as anthihistaminic properties.[2] Recently, diarylmethanols have been used in the synthesis of pharmaceuticals containing asymmetrical 1,1'-diarylalkyl subunits.[3] The most common routes towards diarylmethanols are either enantioselective reductions of prochiral benzophenone derivatives [4] or asymmetric carbon-carbon bond formations starting from aromatic aldehydes and appropriate organometallic compounds. [5,6] Despite the fact that the latter strategy has attracted considerable attention due to its enormous synthetic potential, the so far evaluated substrate range appears rather limited. Thus mostly, aryl transfer reactions onto (unsubstituted) benzaldehyde (Scheme 1, Ar 2 = Ph) or phenyl-to-aldehyde transfers have been studied leading to arylphenylmethanols. The synthesis of diarylmethanols with two differently substituted aryl groups via zinc reagents has, to the best of our knowledge, never been in the focus of an intensive study. [7] In 2002, we described a general approach for aryl transfer reactions to aromatic aldehydes involving arylzinc species formed in situ from arylboronic acids 1 and diethylzinc. Ferrrocene 4 served as catalyst (Scheme 1). [8] Noteworthy is the fact that with a single catalyst both enantiomers of 3 became accessible by choosing the appropriate combination of arylboronic acid 1 and aldehyde 2. Also in this case, only arylphenylmethanols were prepared.Wondering about the flexibility of this method and with the goal to investigate the applicability of the approach in the preparation of more functionalized molecules, we have now studied the catalytic synthesis of 1,1'-disubstituted diarylmethanols (e.g., products with aryls other than phenyl). This involved structural variations of both the arylboronic acids 1 as well as the aldehydes 2. The results are summarized in Table 1.To our delight we found that most diarylmethanols 3 were formed in good yields and high enantioselectivities (Figure 1). For example, 4-chlorophenyl-2'-methylphenylmethanol (3a) was obtained with 91 % ee in 71 % yield (Table 1, entry 1). In the catalysis starting from 2-bromobenzaldehyde (2c) and 3-methoxyphenylboronic acid (1c) diarylmethanol ent-3b was formed with 88 % ee in 66 % yield (entry 3). Using the "reverse combination" of substrates, the enantiomeric product 3b was obtained by aryl transfer from 2-bromophenylboronic acid (1b) ...

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“…Dipyrromethanecarbinols have emerged as key intermediates in rational syntheses of porphyrinic macrocycles bearing meso-substituents in defined positions, including trans-A 2 B 2 -porphyrins [1], ABCD-porphyrins [2], chlorins [3], heteroatom-substituted trans-A 2 B 2 -porphyrins [4], and heteroatom-substituted corroles [5]. The application of dipyrromethanecarbinols depends on acid-catalyzed condensation conditions leading to the porphyrinic macrocycle that provide good yields while avoiding scrambling that could give rise to a mixture of products.…”

Section: Introductionmentioning

confidence: 99%

A survey of acid catalysts in dipyrromethanecarbinol condensations leading to meso-substituted porphyrins

Geier

Callinan

Rao

et al. 2001

J. Porphyrins Phthalocyanines

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ABSTRACT:The successful use of dipyrromethanecarbinols in rational routes to porphyrinic macrocycles requires catalysis conditions that enable irreversible condensation, thereby avoiding substituent scrambling and formation of undesired porphyrin products. Previously, successful conditions of trifluoroacetic acid (TFA) (30 mM) in acetonitrile were identified following a lengthy survey of TFA and BF 3 -etherate catalysis in diverse solvents. In this study, focus was placed on the acid catalyst by examining 17 acids in CH 2 Cl 2 , the traditional solvent for two-step, one-flask porphyrin syntheses. In the self-condensation of the carbinol derived from 1-(4-methylbenzoyl)-5-phenyldipyrromethane, porphyrin yields of 9-55% were obtained from the various acids, compared to 20% under TFA catalysis in acetonitrile. A number of catalytic conditions that produce little to no porphyrin in reactions of pyrrole benzaldehyde afforded good yields of porphyrin and the suppression of scrambling in reactions of dipyrromethanecarbinols. The four best acid catalysts (InCl 3 , Sc(OTf) 3 , Yb(OTf) 3 , and Dy(OTf) 3 ) initially identified were then examined with dipyrromethanecarbinols bearing challenging substituents (alkyl, pyridyl, or no substituent). The greatest improvement was obtained with the pyridyl substrates. Selected reactions performed on a preparative scale (115 to 460 mg of isolated porphyrin) verified the results of the analytical-scale experiments and revealed the more facile isolation of the porphyrin from reactions performed in CH 2 Cl 2 rather than acetonitrile. This study provides alternatives to the use of TFA/acetonitrile that offer advantages in terms of yield and isolation of the porphyrin without sacrificing suppression of scrambling. Furthermore, the finding that poor catalysts for the benzaldehyde pyrrole reaction can be excellent catalysts for dipyrromethanecarbinols provides guidance for the identification of other catalysts for use with reactive precursors in porphyrin-forming reactions.

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Rational Synthesis of Trans-Substituted Porphyrin Building Blocks Containing One Sulfur or Oxygen Atom in Place of Nitrogen at a Designated Site

Cited by 103 publications

References 36 publications

Mono‐functionalized Heteroporphyrin Building Blocks and Unsymmetrical Covalent and Non‐covalent Porphyrin Dyads

Mono‐functionalized Heteroporphyrin Building Blocks and Unsymmetrical Covalent and Non‐covalent Porphyrin Dyads

Diarylmethanols by Catalyzed Asymmetric Aryl Transfer Reactions onto Aldehydes Using Boronic Acids as Aryl Source

A survey of acid catalysts in dipyrromethanecarbinol condensations leading to meso-substituted porphyrins

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