Exploration of meso-substituted formylporphyrins and their Grignard and Wittig reactions

FULL PAPER

DOI: 10.1002/ejoc.200700380

Exploration of meso-Substituted Formylporphyrins and Their Grignard and

Wittig Reactions

Katja Dahms,^[a]Mathias O. Senge,*^[a]and M. Bakri Bakar^[a]

Keywords: Porphyrinoids / Grignard reaction / Wittig reaction / Tetrapyrroles / Umpolung

Formylporphyrins were prepared by using either the 1,3-di-

thian-2-yl residue as a precursor for the CHO group or by

the Vilsmeier reaction. Two synthetic routes for the introduc-

tion of the 1,2-dithian-2-yl group were explored. Further-

more, reactions of the 1,3,5-trithian-2-yl group with porphy-

rins were examined as well as spirobisdithiane derivatives as

precursors for the ultimate assembly of porphyrin spirobisdi-

thanyl-linked bioconjugates. The obtained formylporphyrins

were reacted with organomagnesium or organophosphorus

compounds. A series of hydroxyporphyrins resulting from the

Grignard reaction of 5,15-substituted porphyrins were syn-

thesised in high yields. Several porphyrins with unsaturated

residues introduced by the Wittig reaction were obtained in

moderate yields. The less sterically hindered 5,15-substituted

porphyrins show increased reactivity and give higher yields;

their reaction products are higher in stability relative to other

porphyrin systems.

Germany, 2007)

with methylmagnesium iodide to yield the meso-(1-hydroxy-

ethyl) derivative only as a crude product as decomposition

to the meso-vinyl compound occurred rapidly.^[10]Smith and

co-workers continued these studies by using several Grig-

nard reagents such as methylmagnesium bromide, ethyl-

magnesium bromide and benzylmagnesium chloride and an

acid.^[11]Surprisingly, they did not obtain the expected car-

binol compounds but observed direct meso alkylation at the

15-position opposite to the formyl group. We earlier studied

reactions of β-substituted formylporphyrins with organo-

metallic reagents and found comparable yields and products

for reactions with RLi and RMgX.^[12]For β-substituted

porphyrins, the Wittig reaction has been investigated

in some detail. Callot reported the reactions of

(2,3,7,8,12,13,17,18-octaethyl-5-formylporphyrinato)nickel-

(II) as well as (2-formyl-5,10,15,20-tetraphenylporphyr-

inato)nickel(II) with several Wittig reagents in yields rang-

ing from 29 to 93%.^[13a]Further Wittig condensations were

reported by Arnold et al. who prepared various meso-vinyl

derivatives of nickel porphyrins in yields ranging from 44 to

70%.^[13b]Similarly, McMurry coupling reactions have been

investigated in detail.^[13c]

The porphyrins studied so far in these reactions possess

either meso or β substituents adjacent to the formyl group

that can cause peri interactions, which would result in de-

formation of the macrocycle^[14]or facilitate complex re-

arrangement reactions.^[9,15]To further develop the use of

these core intermediates in porphyrin chemistry, we decided

to investigate the synthesis of β-unsubstituted meso-formyl-

porphyrins and their reactions with Grignard and Wittig

reagents. In light of the increasing use of asymmetrically

substituted porphyrins and the need to develop syntheses

Introduction

Porphyrins are an essential class of natural compounds

that are ubiquitous in nature. They play an important role

in biological processes such as oxygen transport, electron

transfer and photosynthesis.^[1]Their properties also make

them useful in applications ranging from catalysis,^[2]drug

delivery,^[3]nonlinear optics,^[4]photodynamic therapy,^[5]and

the fundamental studies and generation of novel macro-

cycles.^[6]As a result of these properties, they are some of

the most important fine chemicals that are available in in-

dustry, and they are utilised in an ever-expanding array of

applications. Hence, methods to improve the synthesis of

functionalised porphyrins are of fundamental importance.

One functional group, which allows asymmetric modifica-

tion and is widely used in porphyrin chemistry, is the formyl

group.^[7]The formyl fragment can be used to build up alk-

enyl and alkyl chains, cyano groups, carbonic acids,

alcohols and ethers, or they can be use to construct bispor-

phyrins. These compounds can then be used for further re-

actions.

Formylporphyrins have been explored extensively in ge-

neral.^[8,9]However, few reactions using meso-substituted

formylporphyrins for the purpose of functionalising the

porphyrins have been reported. Arnold et al. reported the

reaction of 2,3,7,8,12,13,17,18-octaethyl-5-formylporphyrin

[a] School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Col-

lege Dublin,

Dublin 2, Ireland

Fax: +353-1-8968537

E-mail: sengem@tcd.ie

Eur. J. Org. Chem. 2007, 3833–3848

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K. Dahms, M. O. Senge, M. B. Bakar

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for multichromophore nanomaterials,^[16]we chose 5,15-di- followed by standard workup yielded the double substituted

aryl- and alkylporphyrins as starting material, as they can formylporphyrin 5b in low yield (11%). These reactions al-

be prepared in high yields and purities.^[17]

ready indicated that the stability of the dithian-2-yl residue

is limited under the reaction conditions necessary for por-

phyrin substitution.

Results and Discussion

Dithian-2-ylporphyrins

An effective method for the C–C coupling of different

residues with the porphyrin moiety is the use of organo-

lithium reagents.^[18]This technique can be applied for a

number of different porphyrins with various residues be-

cause of the mild reaction conditions. It can be utilised both

for free-base porphyrins and metalloporphyrins, and the re-

action typically gives products in good-to-excellent yields.

Another approach is the reaction of an organolithium com-

pound with an organosulfur compound. For example, the

reaction of n-butyllithium with 1,3-dithiane at –30 °C in

THF under an atmosphere of argon gives the classical um-

polung synthon for a formyl group, 1,3-dithian-2-yl, which

was developed by Seebach and Corey.^[19]This reaction al-

lows entry into formylporphyrins under nucleophilic condi-

tions.^[20,21]

Investigation of this reaction was carried out with 5,15-

disubstituted porphyrins 1a–f at –78 °C in THF under an

atmosphere of argon. The substitution reaction was pro-

The 1,3,5-trithian-2-yl group could be used in a similar

moted by TMEDA, quenched with water and oxidised by manner, and the reaction of the lithio derivative, the 1,3,5-

DDQ to the corresponding mono-1,3-dithian-2-yl-substi- trithian-2-ylporphyrins 6a–d could be obtained from the re-

tuted porphyrins 2a–f in 4–53% yield (Scheme 1). Ni^IIpor- spective free base and nickel(II) porphyrins in moderate

phyrins generally showed higher yields than the free-base yields from 18–38%. The yields were lower than those of

porphyrins, and because of the steric hindrance of the bulky the related dithian-2-yl reactions. Reaction with the steri-

dithian-2-yl residue, the yields are comparable to those of cally more hindered 2-methyl-1,3-dithiane to yield putative

iPrLi or sBuLi reactions.^[22a]Subsequent treatment with compound 7 was problematic. Spectroscopic evidence indi-

DDQ and BF₃·OEt₂led to deprotection of 2 to the respec- cates the formation of β adducts in low yields.^[23]

tive formylporphyrins 3a–c in varying yields ranging from

39–94%.

The initial success in using the 1,3-dithiane residue for

porphyrin substitution reactions prompted us to investigate

To test the reactivity with more asymmetrical porphyrins, the utility of spirobisdithiane derivatives^[24]for the ultimate

porphyrin 4 was prepared by standard 2+2 condensation construction of porphyrin spirobisdithanyl-linked bioconju-

and then treated with 1,3-dithian-2-yl; workup of this un- gates. Such systems would have significant potential in bio-

optimised reaction yielded a small amount of the depro- medical applications as a drug delivery system owing to the

tected formyl porphyrin 5a. We also attempted to trap the cleavable spirobisdithiane linker. Spirobisdithiane 8 was

in situ generated “porphyrin anion” with electrophiles, akin prepared as described by Kutateladze et al.,^[24a]and its reac-

to the reactions with standard RLi reagents.^[22b]Reaction of tion with n-butyllithium and DMF gave bisaldehyde 9 in

free base 1a with 1,3-dithian-2-yllithium and pentyl iodide 56% yield. As outlined in Scheme 2, the reaction of disub-

Scheme 1. Formylation of porphyrins by the 1,3-dithian-2-yl synthon.

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Exploration of meso-Substituted Formylporphyrins

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stituted porphyrins with the in situ generated spirobisdithi-

anyllithium gave the respective spirobisdithianylporphyrins

11a–e in yields ranging from 19 to 40%.

Scheme 2. Synthesis of spirobisdithiane derivatives.

Unfortunately all attempts to use the spirobisdithianyl

dianion for double substitution reactions failed or gave al-

ternative products. For example, reaction of 1a with the dili-

thio derivative of 8 gave 71% of the respective 5-butyl-sub-

stituted porphyrin and 6% of 11b.

More successful were the attempts to use the 2-formyl-

1,3-dithiane 12^[25]in classic porphyrin condensation reac-

tions (Scheme 3). Reaction with pyrrole generated the 1,3-

dithian-2-yldipyrromethane 13 as a key building block in

almost quantitative yield (96%). Depending on the reaction

conditions, equivalents of reactants and acid, porphyrins

14a–d with two to four meso-dithian-2-yl residues could be

prepared in low-to-moderate yields that are typical for por-

phyrin condensation reactions. Like all dithian-2-yl porphy-

Scheme 3. Condensation reactions involving dithian-2-carbalde-

hyde. Conditions: (a) pyrrole, BF₃·OEt₂, room temp., 40 min, then

NaOH, 96%. (b) CH₂Cl₂, tripyrrane, pyrrole, 45 min, room temp.;

then TFA, room temp., 16 h; then DDQ; then NEt₃, 3%. (c)

CH₂Cl₂, dipyrromethane, TFA, 14 h, room temp.; then DDQ,

10 min, reflux, 16%. (d) CH₂Cl₂, pyrrole, BF₃·OEt₂, 1 h, room

temp.; then NEt₃, DDQ, 4 min, 15%. (e) CH₂Cl₂, pyrrole,

BF₃·OEt₂, 1 h, room temp.; then excess DDQ, 1 h, 46%. (f) CHCl₃,

8 equiv. bis(trifluoroacetoxy)iodobenzene (BTIB), 45 °C, 30 min,

62%. (g) CHCl₃, 4 equiv. BTIB, room temp., 30 min, 30%.

rins, this series showed that the introduction of each di- through the initial formation of the porphyrinogen related

thian-2-yl residue shifts the absorption maxima batho- to 14d followed by acid-catalysed cleavage of one dithian-2-

chromically by about 10 nm. All dithian-2-yl porphyrins ex- yl residue and subsequent oxidation to the porphyrin.^[28,29]

1

hibited very broad signals in the H NMR spectra for the

Despite testing many different reagents for the dethioace-

β protons flanking the dithian-2-yl residues. Variable tem- tylation, only porphyrins with one or two dithian-2-yl resi-

perature NMR showed that these signal became sharper dues could be converted into the formylporphyrins with

(ca. 58 °C) with increasing temperature, which indicates ease. By using bis(trifluoroacetoxy)iodobenzene (BTIB),

that intramolecular hydrogen bonds between the β protons porphyrin 14b was converted into either the mono-formyl-

and the sulfur atoms prevent the free rotation of the di- porphyrin 15a^[30]or the acetal 15b.^[31]Porphyrins such as

thian-2-yl residues at lower temperatures.^[26]

14c or 14d always resulted in the formation of complex mix-

Nevertheless, the oxidative dethioacetylation proved to tures with partially deprotected groups and the loss of indi-

be difficult owing to the low stability and solubility of the vidual meso substituents. Thus, our initial hopes to use the

dithian-2-ylporphyrins with more then two dithian-2-yl res- dithian-2-yl group as a synthon for polyformylporphyrins,

idues or with dithian-2-yl residues in a 5,10 regiochemical which cannot be prepared by Vilsmeier formylation because

arrangement. Porphyrins with one or two dithian-2-yl resi- of the deactivation of the aromatic system, have not yet

dues in a 5,15 orientation are stable, the 5,10 derivative 14a been realised. Nevertheless, this group allows the prepara-

and the tri- 14c and tetrasubstituted porphyrins 14d were tion of free-base formylporphyrins without prior activation

increasingly unstable especially towards traces of acid. The through conversion to the copper(II) or nickel(II) complex,

latter had to be stored under an atmosphere of argon at as is required for classic porphyrin formylation reactions.

–20 °C. The instability of these compounds is a result of

To increase the stability and solubility of the dithian-2-

both increased steric strain in such systems^[27]and the reac- ylporphyrins, we attempted to use 12 or 13 in mixed con-

tivity of the dithian-2-yl residues. For example, formation densation reactions.^[32]Indeed, either 2-formyl-1,3-dithiane

of 14c under the conditions given can only be explained 12 and 5-phenyldipyrromethane or 1,3-dithian-2-yldipyrro-

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K. Dahms, M. O. Senge, M. B. Bakar

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methane 13 and benzaldehyde could be used as starting ma- and 2–3%, respectively. The appearance of compound 16a

terials (Scheme 4). Depending on the reaction conditions, is due to scrambling during the condensation process.^[33]

porphyrins 16a and 16b could be isolated in yields of 2–4 Porphyrins 16a and 16b were both converted into the re-

spective formylporphyrins 17a and 17b in quantitative yield.

Dithian-2-ylporphyrins such as 16 are stable enough to

withstand metallation–demetallation sequences. For exam-

ple, 16a could be converted into zinc(II) porphyrin 18 under

standard metallation conditions^[34]with zinc acetate and

methanol in dichloromethane in 53% yield. Demetallation

was found to be possible, although problematic. For exam-

ple, nickel(II) porphyrin 2b could be demetallated with

BBr₃, albeit in 24% yield only.

An exemplary molecular structure of a dithian-2-ylpor-

phyrin is given in Figure 1. Single-crystal X-ray structure

determination of 16b shows that the S–S vector in each di-

thian-2-yl residue is orthogonal to the mean plane of the

macrocycle (Є 91.3°). The contact between the sulfur atoms

and the neighbouring β hydrogen atoms is 2.971 Å. Al-

though overall planar, the macrocycle exhibits a minor wav

distortion and some core elongation.^[14e–14g]

Vilsmeier Formylation

Whereas the dithian-2-yl synthon offered some new pos-

sibilities for the synthesis of formylporphyrins, the classic

Vilsmeier formylation still has some benefits due to the un-

problematic experimental procedure. To gain more material

for subsequent reactivity studies, we thus prepared a variety

of formyl derivatives of 5,15-disubstituted porphyrins. Me-

tallation was achieved by standard conditions with nickel-

(II) acetate in DMF under reflux conditions and copper(II)

acetate in dichloromethane at room temp. respectively.^[34]

The experimental procedure used for the Vilsmeier for-

mylation was adapted from the one developed by Johnson

and Oldfield.^[35]The yield was between 13 (for 20a) and

97% (for 20h), as summarised in Scheme 5. The low yield

Scheme 4. meso-Substituted dithian-2-ylporphyrins. Conditions: (a)

CH₂Cl₂, 5-phenyldipyrromethane, cat. TFA, 16 h, room temp.; then

DDQ, 45 min, 16a 3%, 16b 2%. (b) CH₂Cl₂, benzaldehyde, cat.

TFA, 16 h, room temp., then DDQ, 45 min, 16a 2%, 16b 4%. (c)

CH₂Cl₂, DDQ, BF₃·OEt₂, room temp., 10 min, 97%. (d) CH₂Cl₂,

ZnOAc, CH₃OH, room temp., 30 min, 53%. (e) H₂SO₄.

Figure 1. Top and side view of the molecular structure of 16b in the

crystal. Thermal ellipsoids are drawn for 50% occupancy; hydrogen

atoms are omitted for clarity.

Scheme 5. Vilsmeier formylations. Conditions: 1,2-dichloroethane,

90 °C, 3–16 h.

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Exploration of meso-Substituted Formylporphyrins

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for compound 20a was a result of problems in separating porphyrin up to 93% for 22d. Though, Smith and co-

the mono- from the diformylated porphyrin. Compounds workers observed the direct meso alkylation of zinc or

3b, 20d and 20e were used as starting material for further metal-free 5-formyloctaethylporphyrin by using Grignard

reactions.

reagents. A regioselective attack at the meso position dia-

metrically opposite to the formyl group of the porphyrin

macrocycle was reported and the unexpected 5-formyl-15-

alkylporphyrin was obtained.^[11]No reaction with the for-

myl group was observed.

Grignard and Wittig Reactions

One reaction type that can be carried out with the formyl

group on the porphyrin is the Grignard reaction.^[10,36]For-

mylporphyrins 3b, 20d and 20e were treated with ethylmag-

nesium bromide (21a), phenylmagnesium bromide (21b)

and allylmagnesium bromide (21c) to obtain compounds

22a–h. The reactions were performed in dry THF under an

atmosphere of argon at room temp. for the reaction be-

tween porphyrins and phenyl- and allylmagnesium bromide

and at 75 °C for the reaction with ethylmagnesium bromide

as reported by Arnold et al.^[10]An excess amount of the

Grignard reagent (10 equiv.) was used for monoformylated

porphyrins 3b and 20d and 20 equiv. for the reaction with

Compound 22g resulting from the reaction of formylpor-

phyrin 3b with allylmagnesium bromide is particularly

interesting as the starting material for further reactions in-

volving the double bond, such as metathesis, to investigate

the activating or deactivating influence of the adjacent hy-

droxy group.

An additional reaction type that can be performed on

formylporphyrins is the Wittig reaction.^[37]Reactions be-

tween methyltriphenylphosphonium bromide (23a), (cya-

nomethyl)triphenylphosphonium chloride (23b) and (4-ni-

trophenyl)triphenylphosphonium bromide (23c) and com-

pounds 3b, 20d and 20e were investigated (Scheme 7).

(5,15-diformyl-10,20-dihexylporphyrinato)nickel(II)

20e.

The yields are given in Scheme 6.

Scheme 7. Wittig reactions.

An excess of the phosphonium salt was suspended in dry

THF and n-butyllithium was added dropwise at room temp.

The suspension was stirred for 5 min to form the ylide in

situ before adding the respective formylporphyrin. The best

Scheme 6. Grignard reactions.

Interestingly, when the diformylated porphyrin 20e was yield was achieved for compound 24a with 81% after heat-

treated with 21a and 21c the resulting (1-hydroxypropyl)- ing at reflux overnight. Moderate yields from 41 to 61%

and (1-hydroxybut-3-enyl)porphyrins were found to be un- were obtained for the vinyl compounds. However, only 10%

stable. The disubstituted (1-hydroxypropyl)porphyrin 22c of compound 24b and 11% of compound 24c could be iso-

could be isolated by column chromatography in 35% yield lated mainly as a result of problems associated with the sep-

and (1-hydroxybut-3-enyl)porphyrin 22h in 9% yield. Both aration of the side products.

porphyrins were characterised by ¹H NMR spectroscopy

In comparison, Callot obtained the (5-vinyl-

but no further characterisation could be accomplished be- 2,3,7,8,12,13,17,18-octaethylporphyrinato)nickel(II) for ex-

cause of the decomposition of the porphyrins. Similar prob- ample in 27% yield. For reactions with different residues

lems were found by Arnold et al. for the reaction of meso- adjacent to the double bond he obtained yields from 69 to

formyloctaethylporphyrin with methylmagnesium bromide 93%.^[13a]Likewise, Arnold et al. investigated different Wit-

and phenylmagnesium bromide.^[10]In contrast, the products tig reactions of (5-formyloctaethylporphyrinato)nickel(II)

of the reactions of ethylmagnesium bromide or allylmagne- and (5-formyletioporphyrinato)nickel(II).^[13b]Various meso-

sium bromide with the monoformylated porphyrins 3b and vinyl derivatives of nickel porphyrins were prepared in

20d or phenylmagnesium bromide with 3b, 20d or 20e were yields ranging from 44% to 70%. Thus, the yields of Wittig

found to be stable. Porphyrins 22a,b and 22d–g were synthe- reactions of meso-substituted porphyrins are comparable to

sised in good yields, ranging from 68% for the disubstituted the results for β-substituted porphyrins.

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K. Dahms, M. O. Senge, M. B. Bakar

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raphy on silica gel was carried out by using a forced flow of the

indicated solvent system on either Fluka Silica Gel 60 (230–

400 mesh) or Fluka Alox (basic). Tetrahydrofuran (THF) was dis-

tilled from sodium/benzophenone under an atmosphere of argon.

All commercial chemicals were supplied by Aldrich and used with-

out further purification. Other conditions were as described be-

fore.^[44]

The expected products bearing unsaturated substituents

can furthermore be applied as precursors for metathesis^[38]

or Diels–Alder reactions^[39]and offer potential use for pho-

todynamic therapy^[17c,40]or in the field of nanoscience.^[41]

Cyanoethenylporphyrin 24a is interesting for further het-

ero-Diels–Alder reactions.^[42]Another synthetic approach

for cyanoethenylporphyrins was reported by Locos and Ar-

nold in 2006.^[43]They described the Heck coupling of bro-

moporphyrins with acrylonitrile. The mono- as well as the

disubstituted alkenylporphyrins were isolated as an insepa-

rable mixture of the cis and trans isomers. In our case, by

employing the Wittig reaction, cyanoethenylporphyrin 24a

was isolated as the trans isomer only in a very good yield

of 81%.

Synthesis of Dithian-2-ylporphyrins

General Procedure A: A dried out, septum-equipped Schlenk flask

under an atmosphere of argon was charged with 1,3-dithiane (1.16,

9.64 mmol). The flask was evacuated under vacuum for 30 min,

and freshly distilled THF (25 mL) was added. The solution was

cooled to –40 °C, and n-butyllithium (2.5 , 3.84 mL, 9.6 mmol)

was added dropwise by syringe through the septum. The reaction

mixture was stirred for 2 h at –30 to –40 °C. The solution of the

organometallic compound was cooled to –78 °C and mixed with a

suspension (–78 °C) of the porphyrin (0.45 mmol) in absolute THF

(20 mL). After transfer of the porphyrin suspension, N,N,N,N-tet-

ramethylethylenediamine (0.25 mL, 1.6 mmol) was added, and the

reaction mixture turned dark brown. After stirring for 1 min, the

cold bath was removed, and the reaction mixture was stirred for

15 min. Water (6 mL) was added by syringe, which resulted in an

immediate colour change to dark green. The mixture was stirred

for 15 min at room temp., followed by the addition of a solution

of DDQ (0.6 g, ca. 0.75 mmol) in THF (10 mL), and the colour of

the solution changed to purple. Stirring was continued for 15 min,

followed by filtration of the reaction mixture through silica

(200 mL) and washing with CH₂Cl₂. The eluted porphyrin frac-

tions were evaporated to dryness and washed with n-hexane

(2ϫ10 mL). The residue was purified by column chromatography

(silica, CH₂Cl₂/C₆H₁₄, 3:1), and the target compounds were ob-

tained as the second fraction.

Conclusions

Umpolung reactions were used to synthesise six 1,3-di-

thian-2-yl porphyrins 2a–f in moderate yields. Porphyrins

2a, 2b and 2d were deprotected to the corresponding for-

mylporphyrins 3a–c. This shows that this method offers a

new pathway for the preparation of formylporphyrins in

their free base form as well as metalloporphyrins under

milder reaction conditions with yields comparable to the

Vilsmeier reaction. Owing to the low stability of polydithi-

anylporphyrins, access to meso-polyformylporphyrins could

not be realised with the use of this method. Nonetheless,

the Vilsmeier reaction is still the most common way for in-

troducing the formyl group into the porphyrin moiety. Por-

phyrins 3b and 20a–h were synthesised by using this

method.

To demonstrate the wide range of applications for the

formyl group to yield functionalised porphyrins, studies of

Grignard and Wittig reactions of 5,15-disubstituted por-

phyrins were performed. The yields of porphyrins 22a–f and

24a–e ranged from 54 to 93% and from 10 to 81%, respec-

tively. These yields are much better then those from similar

reactions with 5-formyl-2,3,7,8,12,13,17,18-octaethylpor-

phyrins. Hence, the lower steric hindrance present in the

5,15-substituted porphyrins facilitates their reactivity and,

as a result, the yields and stability of the resulting porphy-

rins.

5-(1,3-Dithian-2-yl)-10,20-diphenylporphyrin (2a): Procedure A,

yield: 120 mg (0.207 mmol, 47%) of purple crystals. M.p. 290 °C.

R_f= 0.2 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR (250 MHz, CDCl₃, 20 °C):

δ = –3.03 (br. s, 2 H, NH), 2.53 (m, 2 H, 5⁴-CH₂), 3.31 (m, 2 H,

S–CH₂), 3.63 (m, 2 H, S–CH₂), 7.78 (m, 6 H, Ar_o,p-H), 7.87 (s, 1 H,

5¹-CH), 8.21 (m, 4 H, Ar_m-H), 8.92 (AB/AB, ³J = 8.1 Hz, ⁴J =

3

4.7 Hz, 4 H, 12,13,17,18-H_β), 9.25 (AB, J = 4.6 Hz, 2 H, 2,8-H_β),

9.71 (br. s, 1 H, 3- or 7-H_β), 10.12 (s, 1 H, 15-H_meso), 10.71 (br. s,

1 H, 3- or 7-H_β) ppm. ¹³C NMR (60 MHz, CDCl₃, 20 °C): δ =

26.21, 35.87, 54.51, 105.74, 114.53, 126.74, 127.77, ≈132, 134.60,

141.90 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 416 (5.49), 512 (4.02),

544 (3.23), 586 (3.45), 640 (2.72) nm. MS (EI, 80 eV, 200 °C): m/z

(%) = 580 (100) [M]⁺, 519 (33) [M – C₂H₅S]⁺, 506 (62) [M –

C₃H₆S]⁺, 476 (86) [M – C₃H₄S₂]⁺, 462 (17) [M – C₄H₆S₂]⁺, 290 (8)

[M]²⁺

. HRMS (EI): calcd. for C₃₆H₂₈N₄S₂580.1755; found

580.1772.

Experimental Section

Instrumentation and General Considerations: ¹H and ¹³C NMR

[5-(1,3-Dithian-2-yl)-10,20-diphenylporphyrinato]nickel(II)

(2b):

spectra were recorded with a Bruker DPX 400 (400.13 MHz for

Procedure A, yield: 140 mg (0.22 mmol, 53%) of purple crystals.

¹H NMR; 100.61 MHz for ¹³C NMR) and/or a Bruker AV 600 M.p. Ͼ300 °C. R_f

=

0.60 (CH₂Cl₂/C₆H₁₄, 1:1). ¹H NMR

(600.13 MHz for ¹H NMR; 150.90 MHz for ¹³C NMR). Chemical

shifts are reported in ppm referenced to tetramethylsilane (δ =

0.00 ppm). High-resolution mass spectra and low-resolution mass

spectra were recorded with Micromass/Waters Corp. USA Quattro

micro LC–MS/MS and with a Finnigan SSQ 710 GC–MS, GC–

TOF and ESI/APCI-Q-TOF_micro. UV/Vis measurements were per-

formed with a Shimadzu Multispec-1501. Melting points were ac-

quired with a Stuart SMP10 melting point apparatus and are un-

corrected. Thin-layer chromatography (TLC) was performed on sil-

ica gel 60F₂₅₄(Merck) precoated aluminium sheets. Chromatog-

(300 MHz, CDCl₃, 20 °C): δ = 2.45 (m, 2 H, CH₂–CH₂–CH₂) 3.22

(m, 2 H, S–CH₂), 3.45 (m, 2 H, S–CH₂), 7.24 (s, 1 H, S–CH–S),

7.69 (m, 6 H, Ar_o,p-H), 7.99 (m, 4 H, Ar_m-H), 8.78 (m, 4 H,

3

12,13,17,18-H_β), 9.02 (AB, J = 4.8 Hz, 2 H, 2,8-H_β), 9.65 (s, 1 H,

15-H_meso), 9.88 (br. s, 2 H, 3,7-H_β) ppm. ¹³C NMR (63 MHz,

CDCl₃, 20 °C): δ = 26.00, 35.20, 52.77, 104.99, 112.55, 118.37,

126.87, 127.73, 132.32, 132.37, 133.66, 140.54, 141.88, 142.14,

142.55 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 413 (5.09), 529 (4.07),

560 (3.71) nm. MS (70 eV): m/z (%) = 636 (4) [M]^·+, 575 (7) [M –

C₂H₅S]⁺, 562 (10) [M – C₃H₆S]⁺, 532 (2.5) [M – C₃H₄S₂]⁺, 518 (4)

3838

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Eur. J. Org. Chem. 2007, 3833–3848

Exploration of meso-Substituted Formylporphyrins

[M HRMS (EI): calcd. for

C₄H₆S₂]⁺, 318 (2) [M]²⁺

FULL PAPER

3

–

.

CH₂), 3.49 (m, 2 H, S–CH₂), 4.52 (d, J = 7.2 Hz, 4 H, CH–CH₂),

7.14 (s, 1 H, –S–CH–S–), 9.03 (AB, ³J = 5.2 Hz, 2 H, H_β), 9.30

(AB/AB, ³J = 6.0 Hz, ⁴J = 5.0 Hz, 4 H, 2,3,17,18-H_β), 9.47 (s, 1 H,

20-H_meso), 9.86 (br. s, 2 H, 8,12-H_β) ppm. ¹³C NMR (63 MHz,

CDCl₃, 20 °C): δ = 22.99, 26.09, 34.38, 35.19, 42.14, 52.65, 104.05,

111.22, 116.46, 130.41, 132.46, 139.87, 141.02, 142.00, 142.87 ppm.

UV/Vis (CH₂Cl₂): λ (log ε) = 416 (5.45), 534 (4.11), 568 (3.59) nm.

MS (EI, 70 eV): m/z (%) = 596 (5) [M]^·+, 553 (6) [M – C₂H₅S]⁺,

535 (7) [M – C₃H₇]⁺, 522 (11) [M – C₃H₆S]⁺, 492 (4) [M –

C₃H₄S₂]⁺, 481 (17.5) [M – C₈H₁₈]⁺, 298 (2) [M]²⁺. HRMS (EI):

calcd. for C₃₂H₃₄N₄S₂596.1578; found 596.1576.

C₃₆H₂₆N₄NiS₂636.0952; found 636.0956.

5-(1,3-Dithian-2-yl)-10,20-bis(3-methoxyphenyl)porphyrin (2c): Pro-

cedure A, yield: 15 mg (0.0234 mmol, 4%) of purple crystals. M.p.

268 °C. R_f= 0.09 (CH₂Cl₂/C₆H₁₄, 1:1). ¹H NMR (300 MHz,

CDCl₃, 20 °C): δ = –3.03 (br. s, 2 H, NH), 2.55 (m, 2 H, CH₂–

CH₂–CH₂), 3.33 (m, 2 H, S–CH₂), 3.64 (m, 2 H, S–CH₂), 4.00 (s,

6 H, OCH₃), 7.37 (m, 2 H, Ar_H), 7.69 (m, 2 H, Ar_H), 7.82 (m, 5

H, Ar_H, S–CH–S, Ar_m-H), 8.98 (m, 4 H, 12,13,17,18-H_β), 9.27 (AB,

³J = 4.5 Hz, 2 H, 2,8-H_β), 9.65 (br. s, 1 H, H_β), 10.14 (s, 1 H, 15-

H_meso),10.63 (br., 1 H, H_β) ppm. ¹³C NMR (63 MHz, CDCl₃,

20 °C): δ = 35.88, 55.54, 113.71, 120.47, 127.55, 127.71, 127.80,

143.21, 158.02 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 417 (5.29), 513

(3.81), 557 (3.38), 588 (3.41), 648 (3.25) nm. MS (EI, 80 eV,

200 °C): m/z (%) = 640 (2) [M]^·+, 580 (5) [M – C₂H₄S]⁺, 522 (7)

[M – C₄H₆S₂]⁺. HRMS (EI): calcd. for C₃₈H₃₂N₄O₂S₂640.1967;

found 640.1979. Ϫ Alternatively this compound was prepared by

demetallation of 2d. Ni^IIcomplex 2d (70 mg, 0.1 mmol) was dis-

solved under an atmosphere of Ar in dry CH₂Cl₂(15 mL) and co-

oled to –70 °C. BBr₃(4 mL) was added dropwise, and the red solu-

tion turned green. After removal of the cold bath, the mixture was

stirred for 12 h at room temp. Water was then added slowly for

hydrolysis, and the mixture was extracted with water (2ϫ20 mL)

and a saturated NaHCO₃solution (20 mL) and dried with Na₂SO₄.

The solvent was removed under reduced pressure and recrystalli-

sation from CH₂Cl₂/CH₃OH gave 15 mg (0.02 mmol, 24%) of the

title compound.

Deprotection of the Dithian-2-ylporphyrins

General Procedure B: To a solution of dithian-2-ylporphyrin

(0.06 mmol) in CH₂Cl₂(60 mL) was added DDQ (500 mg,

2.20 mmol) and BF₃·Et₂O (0.5 mL, 9.95 mmol), and the colour of

the red solution changed over yellow to green. After stirring for

45 min, the reaction was quenched by the addition of aqueous so-

dium hydrogen carbonate. The organic phase was washed with a

saturated solution of sodium hydrogen carbonate several times, fol-

lowed by drying over anhydrous sodium sulfate and evaporation of

the solvent in vacuo. After filtration through silica gel and

recrystallisation from CH₂Cl₂/MeOH the pure product could be

obtained.

5-Formyl-10,20-diphenylporphyrin (3a): Procedure B, yield: 13 mg

(0.03 mmol, 44%) of purple crystals. M.p. Ͼ310 °C. R_f= 0.53

(CH₂Cl₂/C₆H₁₄, 2:1). ¹H NMR (300 MHz, CDCl₃, 20 °C): δ =

–2.54 (br. s, 2 H, NH), 7.81 (m, 6 H, Ar_o,p-H), 8.18 (dd, ³J = 6.0 Hz,

⁴J = 1.5 Hz, 4 H, Ar_m-H), 8.85 (AB, ³J = 4.5 Hz, 2 H, H_β), 9.02

[5-(1,3-Dithian-2-yl)-10,20-bis(3-methoxyphenyl)porphyrinato]nickel-

3

(II) (2d): Procedure A, yield: 167 mg (0.239 mmol, 53%) of purple

(AB, J = 4.9 Hz, 2 H, 2,8-H_β), 9.22 (AB, J = 4.5 Hz, 2 H, H_β),

10.11 (AB, ³J = 4.7 Hz, 2 H, 3,7-H_β), 10.18 (s, 1 H, 15-H_meso),

12.52 (s, 1 H, CHO) ppm. ¹³C NMR (63 MHz, CDCl₃, 20 °C): δ

1

crystals. M.p. Ͼ300 °C. R_f= 0.10 (CH₂Cl₂/C₆H₁₄, 1:1). H NMR

(300 MHz, CDCl₃, 20 °C): δ = 2.44 (m, 2 H, CH₂–CH₂–CH₂), 3.22

(m, 2 H, S–CH₂), 3.49 (m, 2 H, S–CH₂), 3.94 (s, 6 H, OCH₃), 7.25 = 108.08, 109.87, 122.13, 124.92, 126.94, 127.80, 128.10, 128.64,

(m, 4 H, Ar_o,p-H), 7.60 (m, 5 H, Ar_m-H, S–CH–S), 8.82 (m, 4 H, 130.19, 131.18, 133.86, 134.42, 141.18, 195.15 ppm. UV/Vis

3

12,13,17,18-H_β), 9.02 (AB, J = 4.8 Hz, 2 H, 2,8-H_β), 9.65 (s, 1 H, (CH₂Cl₂): λ (log ε) = 411 (5.49), 508 (3.95), 561 (3.47), 581 (3.56),

15-H_meso), 9.87 (br. s, 2 H, 3,7-H_β) ppm. ¹³C NMR (60 MHz,

CDCl₃, 20 °C): δ = 25.99, 35.20, 52.75, 55.42, 105.02, 112.58,

113.58, 118.14, 119.57, 126.68, 127.75, 132.44, 132.64, 141.17,

141.76, 141.83, 142.19, 142.44, 158.13 ppm. UV/Vis (CH₂Cl₂): λ

(log ε) = 413 (5.13), 529 (4.16), 560 (3.80) nm. MS (EI, 70 eV):

m/z (%) = 698 (2) [M]^·+, 537 (2.5) [M – C₂H₅S]⁺, 624 (2) [M –

C₃H₆S]⁺, 349 (1) [M]²⁺. HRMS (EI): calcd. for C₃₈H₃₀N₄NiO₂S₂

696.1164; found 696.1138.

647 (3.30) nm. MS (70 eV): m/z (%) = 490 (23) [M]^·+, 462 (6) [M –

CO]⁺, 245 (16) [M]²⁺. HRMS (EI): calcd. for C₃₃H₂₂N₄O 490.1794;

found 490.1777.

(5-Formyl-10,20-diphenylporphyrinato)nickel(II) (3b): Procedure B,

yield: 13 mg (0.02 mmol, 39%) of purple crystals. M.p. 215 °C. R_f

1

= 0.59 (CH₂Cl₂/C₆H₁₄, 2:1). H NMR (300 MHz, CDCl₃, 20 °C):

3

4

δ = 7.72 (m, 6 H, Ar_o,p-H), 7.98 (dd, J = 5.8 Hz, J = 1.5 Hz, 4 H,

3

Ar_m-H), 8.74 (AB, J = 4.8 Hz, 2 H, H_β), 8.89 (AB, J = 5.2 Hz, 2

H, 2,8-H_β), 9.05 (AB, ³J = 4.8 Hz, 2 H, H_β), 9.75 (s, 1 H, 15-H_meso),

5,15-Diisobutyl-10-(1,3-dithian-2-yl)porphyrin (2e): Procedure A,

yield: 24 mg (0.044 mmol, 10.1%) of purple crystals. M.p. 268 °C.

R_f= 0.30 (CH₂Cl₂/C₆H₁₄, 1:1). ¹H NMR (300 MHz, CDCl₃,

20 °C): δ = –2.91 (s, 2 H, NH), 1.19 [d, ³J = 6.6 Hz, 12 H, CH-

(CH₃)₂], 2.57 [m, 2 H, CH(CH₃)₂], 2.76 (m, 2 H, –CH₂CH– 3.35

9.86 (AB, ³J = 5.2 Hz, 2 H, 3,7-H_β), 12.13 (s, 1 H, CHO) ppm. ¹³

C

NMR (63 MHz, CDCl₃, 20 °C): δ = 106.49, 108.59, 111.61, 127.04,

128.08, 130.53, 132.38, 133.19, 133.53, 135.29, 141.80, 144.26,

173.52 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 417 (5.31), 545 (3.75),

589 (3.94) nm. MS (EI, 70 eV): m/z = 546 (18) [M]^·+, 517 (16) [M –

3

(m, 2 H, S–CH₂), 3.66 (m, 2 H, S–CH₂), 4.81 (d, J = 7.2 Hz, 4 H,

CHO]⁺, 440 (52) [M

–

C₇H₆O]⁺. HRMS (EI): calcd. for

CH₂–CH), 7.89 (s, 1 H, S–CH–S), 9.27 (AB, ³J = 5.0 Hz, 2 H, H_β),

3

C₃₃H₂₀N₄NiO 546.0991; found 546.0989.

9.45 (AB, J = 4.6 Hz, 2 H, H_β), 9.52 (AB, J = 5.0 Hz, 2 H, H_β),

9.77 (br. s, 1 H, H_β), 9.98 (s, 1 H, 20-H_meso), 10.78 (br. s, 1 H, H_β)

ppm. ¹³C NMR (63 MHz, CDCl₃, 20 °C): δ = 23.32, 26.32, 35.95,

36.65, 36.71, 43.41, 54.98, 104.93, 113.18, 120.99 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 416 (5.57), 514 (4.17), 547 (3.58), 590 (3.63),

646 (3.45) nm. MS (EI, 70 eV): m/z (%) = 540 (1) [M]^·+, 423 (2)

[M – C₂H₄S]⁺, 407 (40) [M – C₅H₉S₂]⁺. HRMS (EI): calcd. for

C₃₂H₃₆N₄S₂540.2381; found 540.2381.

[5-Formyl-10,20-bis(3-methoxyphenyl)porphyrinato]nickel(II) (3c):

Procedure B, yield: 34 mg (0.05 mmol, 94%) of dark purple crys-

tals. M.p. Ͼ300 °C. R_f= 0.26 (CH₂Cl₂/C₆H₁₄, 2:1). ¹H NMR

(300 MHz, CDCl₃, 20 °C): δ = 3.95 (s, 6 H, OCH₃), 7.58 (m, 8 H,

3

Ar_o,m,p-H), 8.77 (AB, J = 4.8 Hz, 2 H, H_β), 8.93 (AB, J = 5.2 Hz,

2 H, 2,8-H_β), 9.03 (AB, ³J = 4.8 Hz, 2 H, H_β), 9.72 (s, 1 H, 15-

H_meso), 9.84 (AB, J = 5.2 Hz, 2 H, 3,7-H_β), 12.11 (s, 1 H, CHO)

3

ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 419 (4.69), 545 (3.47), 592 (3.56)

nm. MS (ESI): m/z (%) = 606 (100) [M]^·+. HRMS (EI): calcd. for

C₃₅H₂₄N₄NiO₃606.1202; found 606.1190.

[5,15-Diisobutyl-10-(1,3-dithian-2-yl)porphyrinato]nickel(II)

(2f):

Procedure A, yield: 128 mg (0.214 mmol, 49%) of purple crystals.

1

M.p. 250 °C. R_f= 0.30 (CH₂Cl₂/C₆H₁₄, 1:1). H NMR (300 MHz,

CDCl₃, 20 °C): δ = 0.84 [d, ³J = 6.6 Hz, 12 H, CH(CH₃)₂], 2.22 5-Hexyl-15-phenylporphyrin (4): Dry CH₂Cl₂(2 L) was placed in a

[m, 2 H, CH(CH₃)₂], 2.46 (m, 2 H, –CH₂CH–), 3.24 (m, 2 H, S– three-necked flask equipped with magnetic stirrer, gas inlet (argon)

Eur. J. Org. Chem. 2007, 3833–3848

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3839

K. Dahms, M. O. Senge, M. B. Bakar

FULL PAPER

and a reflux condenser. Dipyrromethane (1.2 g, 8.2 mmol), benzal-

dehyde (0.46 mL, 4.6 mmol), and heptanal (0.64 mL, 4.6 mmol)

were added. The flask was shielded from ambient light and then

TFA (140 µL, 1.8 mmol) was added, and the reaction mixture was

stirred for 18 h at room temp. After this time, DDQ (2.77 g,

12.2 mmol) suspended in dry CH₂Cl₂(100 mL) was added, and the

mixture was stirred for 1 h. Triethylamine (6 mL) was then added,

and the reaction mixture was concentrated in vacuo to about

200 mL. The reaction mixture was filtered through silica (500 mL,

column diameter 5 cm), washing with CH₂Cl₂. The eluted porphy-

rin fractions were evaporated to dryness. The porphyrins were sepa-

rated by column chromatography (silica, CH₂Cl₂/C₆H₁₄, 1:1). The

first fraction was 5,15-dihexylporphyrin (45 mg, 0.09 mmol, 4%),

the second fraction, 5-phenyl-15-hexylporphyrin (189 mg,

0.40 mmol, 14%) and the third fraction 5,15-diphenylporphyrin

(65 mg, 0.14 mmol, 6%). The porphyrins were recrystallised from

CH₂Cl₂/MeOH. The suspension was filtered through a D3 frit leav-

ing behind purple crystals of the title compound. M.p. Ͼ310 °C. R_f

= 0.86 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ

= –3.08 (s, 2 H, NH), 1.05 (t, J = 7.6 Hz, 3 H, 5⁶-CH₃), 1.48 (m,

2 H, 5⁵-CH₂), 1.51 (m, 2 H, 5⁴-CH₂), 1.86 (m, 2 H, 5³-CH₂), 2.58

(m, 2 H, 5²-CH₂), 4.96 (t, J = 8.0 Hz, 2 H, 5¹-CH₂), 7.89 (m, 3 H,

Ar_H), 8.33 (m, 2 H, Ar_H), 9.12 (d, J = 4.5 Hz, 2 H, H_β), 9.38 (d, J

= 4.5 Hz, 4 H, H_β), 9.56 (d, J = 7.6 Hz, 2 H, H_β), 10.19 (s, 2 H,

H_meso) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = 13.8, 22.4,

29.9, 31.5, 34.3, 38.4, 104.3, 117.9, 126.6, 127.5, 130.3, 131.3, 134.5,

141.0, 144.3, 147.0 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 408 (4.55),

427 (4.74), 503 (2.90), 539 (3.13), 573 (3.39), 620 (3.33) nm. HRMS

(ES+): calcd. for C₃₂H₃₀N₄[M + H]⁺471.2549; found 471.2553.

1 H, H_β), 10.12 (d, J = 5.3 Hz, 1 H, H_β), 10.15 (s, 1 H, H_meso),

12.55 (s, 1 H, CHO) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ

= 13.7, 22.3, 28.9, 31.5, 35.0, 38.3, 107.1, 109.2, 126.6, 127.6, 133.9,

140.6, 194.9 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 423 (4.02), 458

(3.99), 502 (2.78), 572 (2.78), 601 (2.90), 655 (3.18) nm. HRMS

(ES+): calcd. for C₃₈H₃₃N₄O [M + H]⁺499.2514; found 499.2498.

5-Formyl-15-pentyl-10,20-diphenylporphyrin (5b): 1,3-Dithiane

(0.58 g, 4.82 mmol) was placed in a dried, septum-equipped

Schlenk flask under an atmosphere of argon. The flask was evacu-

ated for 30 min, then backfilled with argon and charged with

freshly distilled THF (25 mL). The solution was cooled to –40 °C

and n-butyllithium (2.5 , 1.92 mL, 4.8 mmol) was added dropwise

by syringe through the septum. The reaction mixture was stirred

for 30–40 min at –30 to –40 °C. The solution of the organometallic

compound was cooled to –78 °C and mixed with a suspension

(–30 °C) of 5,15-diphenylporphyrin 1a (100 mg, 0.22 mmol) in

THF (20 mL). After transfer of the porphyrin suspension,

N,N,NЈ,NЈ-tetramethylethylenediamine (0.2 mL, 1.6 mmol) was

added, and the reaction mixture turned dark brown. After stirring

for 15 min, the cold bath was removed, and the reaction mixture

was stirred for 1 h at room temp. The solution was treated with n-

pentyl iodide (0.7 mL, 0.42 mmol) and stirred for 2 d. Water (3 mL)

was added by syringe, resulting in an immediate colour change of

the solution to dark green. The mixture was stirred for 15 min at

room temp, followed by the addition of a solution of DDQ (0.3 g,

ca. 0.75 mmol) in THF (10 mL), and the colour of the solution

changed from green to purple. Stirring was to continue for 15 min,

followed by filtration of the mixture through silica (200 mL) wash-

ing with CH₂Cl₂. The eluted porphyrins were evaporated to dryness

and further purified by column chromatography (silica, CH₂Cl₂/

C₆H₁₄, 2:1) to yield the compound as a side product (13.55 mg,

0.02 mmol, 11%) as a purple solid. M.p. Ͼ310 °C. R_f= 0.87

5-Formyl-10-hexyl-20-phenylporphyrin (5a): 1,3-Dithiane (0.56 g,

4.67 mmol) was placed in a dried, septum-equipped Schlenk flask

under an atmosphere of argon. The flask was evacuated for 30 min,

then backfilled with argon and charged with freshly distilled THF

(25 mL). The solution was cooled to –40 °C and n-butyllithium

(2.5 , 1.87 mL, 4.67 mmol) was added dropwise by syringe

through the septum. The reaction mixture was stirred for 30–

40 min at –30 to –40 °C. The solution of the organometallic com-

pound was cooled to –78 °C and mixed with a suspension (–30 °C)

of 5-hexyl-15-phenylporphyrin 4 (100 mg, 0.21 mmol) in THF

(20 mL). After transfer of the porphyrin suspension, N,N,NЈ,NЈ-

tetramethylethylenediamine (0.2 mL, 1.6 mmol) was added, and the

reaction mixture turned dark-brown. After stirring for 15 min, the

cold bath was removed, and the reaction mixture was stirred for 1 h

at room temp. The solution was then treated with n-propyl iodide

(0.7 mL, 0.42 mmol) and heated at reflux for an additional day.

Water (3 mL) was added by syringe, resulting in an immediate col-

our change of the solution to dark green. The mixture was stirred

for 15 min at room temp, followed by the addition of a solution of

DDQ (0.3 g of DDQ, ca. 0.75 mmol) in THF (10 mL), and the

colour of the solution changed from green to purple. Stirring was

continued for 15 min, followed by filtration of the mixture through

silica (200 mL) washing with CH₂Cl₂. The eluted porphyrins were

evaporated to dryness and further purified by column chromatog-

raphy (silica, CH₂Cl₂/C₆H₁₄, 2:1) to yield the compound as a side

product (2.2 mg, 0.02 mmol, 2.1%) as a purple solid. M.p.

1

(CH₂Cl₂). H NMR (400 MHz, CDCl₃, 20 °C): δ = –1.81 (s, 2 H,

NH), 0.98 (t, J = 7.6 Hz, 3 H, 5⁵-CH₃), 1.55 (m, 2 H, 5⁴-CH₂),

1.77 (m, 2 H, 5³-CH₂), 2.50 (m, 2 H, 5²-CH₂), 4.88 (t, J = 8.2 Hz,

2 H, 5¹-CH₂), 7.79 (m, 6 H, Ar_H), 8.16 (d, J = 7.0 Hz, 4 H, Ar_H),

8.75 (d, J = 4.7 Hz, 2 H, H_β), 8.90 (d, J = 4.7 Hz, 2 H, H_β), 9.37

(d, J = 4.7 Hz, 2 H, H_β), 9.94 (d, J = 5.2 Hz, 2 H, H_β), 12.41 (s, 1

H, CHO) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = 13.7,

22.3, 29.3, 31.5, 38.0, 126.3, 127.4, 129.8, 133.7, 141.3, 194.0 ppm.

UV/Vis (CH₂Cl₂): λ (log ε) = 422 (4.91), 441 (4.99), 523 (4.12), 563

(4.13), 592 (4.13), 652 (4.15) nm. HRMS (ES+): calcd. for

C₃₈H₃₃N₄O [M + H]⁺561.2665; found 561.2654.

5,15-Diphenyl-10-(1,3,5-trithian-2-yl)porphyrin (6a): n-Butyllithium

(2.5 , 1.92 mL, 4.8 mmol) was added under an atmosphere of ar-

gon to a 100-mL Schlenk flask charged with a solution of 1,3,5-

trithiane (0.67, 4.84 mmol) in dry THF (20 mL) at –40 °C. The

reaction mixture was then stirred for 2.5 h at 20 °C. The solution

of the organometallic compound was cooled to –78 °C and mixed

with a suspension (–30 °C) of 5,15-diphenylporphyrin 1a (100 mg,

0.22 mmol) in THF (20 mL). After transferring the porphyrin

suspension,

N,N,NЈ,NЈ-tetramethylethylenediamine

(0.2 mL,

1.6 mmol) was added, and the reaction mixture turned dark brown.

After stirring for 15 min, the cold bath was removed, and the reac-

tion mixture was stirred for 1 h at room temp. Subsequently, water

Ͼ310 °C. R_f= 0.71 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR (400 MHz, (3 mL) was added for hydrolysis. The mixture was stirred for an-

CDCl₃, 20 °C): δ = –2.50 (s, 2 H, NH), 0.97 (t, J = 7.3 Hz, 3 H,

other 15 min at room temp, followed by the addition of a solution

5⁶-CH₃), 1.44 (m, 2 H, 5⁵-CH₂), 1.54 (m, 2 H, 5⁴-CH₂), 1.83 (m, 2 of DDQ (0.3 g, ca. 0.75 mmol) in THF (10 mL), and the colour of

H, 5³-CH₂), 2.52 (m, 2 H, 5²-CH₂), 4.90 (t, J = 7.7 Hz, 2 H, 5¹- the solution changed to purple. Stirring was continued for another

CH₂), 7.83 (m, 6 H, Ar_H), 8.19 (d, J = 7.16 Hz, 4 H, Ar_H), 8.85

15 min, and the organic solvent was removed under vacuum. Final

(d, J = 4.7 Hz, 1 H, H_β), 9.00 (d, J = 4.7 Hz, 1 H, H_β), 9.24 (d, J purification was achieved by column chromatography (EtOAc/

= 4.7 Hz, 1 H, H_β), 9.32 (d, J = 4.1 Hz, 1 H, H_β), 9.43 (d, J = C₆H₁₄, 1:20) under dark conditions to yield title compound 6a

4.7 Hz, 1 H, H_β), 9.59 (d, J = 5.3 Hz, 1 H, H_β), 9.99 (d, J = 4.7 Hz, (24 mg, 0.04 mmol, 18%) as a purple solid. M.p. Ͼ310 °C. R_f=

3840

www.eurjoc.org

Eur. J. Org. Chem. 2007, 3833–3848

Exploration of meso-Substituted Formylporphyrins

0.83 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ lithium (2.5 , 9.9 mL, 15.99 mmol) was added dropwise by syringe

FULL PAPER

= –3.06 (s, 2 H, NH), 4.36 (d, J = 14.6 Hz, 2 H, S–CH₂–S), 5.06

(d, J = 14.6 Hz, 2 H, S–CH₂), 7.78 (m, 6 H, Ar_H), 7.94 (s, 1 H,

through the septum, and the reaction mixture was stirred for 2 h

at –25 °C. The solution of the organometallic compound was co-

S–CH–S), 8.18 (d, J = 7.0 Hz, 4 H, Ar_H), 8.91 (d, J = 15.2 Hz, 4 oled to –78 °C and mixed with a suspension (–10 °C) of DMF

H, H_β), 9.25 (s, 2 H, H_β), 9.52 (s, 1 H, H_β), 10.13 (s, 1 H, H_meso), (10 mL). The solution was stirred for 2 h at –10 °C and the colour

10.50 (s, 1 H, H_β) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = of the solution turned to light yellow. The solution was then stored

30.5, 40.9, 57.7, 105.6, 113.3, 126.4, 127.4, 134.2, 141.3 ppm. UV/ in the freezer overnight. For workup, the solution was poured into

Vis (CH₂Cl₂): λ (log ε) = 415 (4.25), 512 (3.52), 548 (3.42), 587

(3.43), 640 (3.39) nm. HRMS (ES+): calcd. for C₃₉H₃₂N₄S₄[M +

H]⁺599.1398; found 599.1411.

ice, and the aqueous phase was extract with hexane. The aqueous

phase was then neutralised with HCL (1 ) before extraction with

CH₂Cl₂for the second time. The organic phase was dried with

MgSO₄, and the organic solvent was removed under vacuum. The

remaining yellow oil was recrystallised from C₆H₁₄/CH₂Cl₂and

gave the title compound (0.70 g, 2.49 mmol, 56%) as a yellow solid.

M.p. 165 °C. ¹H NMR (400 MHz, CDCl₃, TMS): δ = 2.86 (s, 4

H, –S–CH₂–), 2.94 (s, 4 H, –S–CH₂–), 4.03 (s, 2 H, –S–CH–S–),

9.39 (s, 2 H, -CHO) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 29.72,

30.99, 36.06, 46.63, 186.86 ppm.

[5,15-Diphenyl-10-(1,3,5-trithian-2-yl)porphyrinato]nickel(II) (6b):

The reaction was performed with the use of the same conditions

as for free base 6a by using 1,3,5-trithiane (0.55 g, 4.01 mmol), n-

butyllithium (2.5 , 1.60 mL, 4.0 mmol) and (5,15-diphenylporphy-

rinato)nickel(II) 1b (100 mg, 0.18 mmol). Elution with CH₂Cl₂/

C₆H₁₄(1:1) yielded the title compound (46 mg, 0.07 mmol, 38%)

as a purple solid. M.p. Ͼ310 °C. R_f= 0.89 (CH₂Cl₂/C₆H₁₄, 2:1).

¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 4.27 (d, J = 15.2 Hz, 2

H, S–CH₂–S), 4.92 (d, J = 14.6 Hz, 2 H, S–CH₂–S), 7.30 (s, 1 H,

S–CH–S), 7.68 (m, 6 H, Ar_H), 7.95 (d, J = 6.4 Hz, 4 H, Ar_H), 8.77

(m, J = 4.7 Hz, 4 H, H_β), 9.02 (d, J = 4.7 Hz, 2 H, H_β), 9.67 (s, 1

H, H_meso), 9.72 (s, 2 H, H_β) ppm. ¹³C NMR (100 MHz, CDCl₃,

20 °C): δ = 35.0, 40.3, 56.0, 102.6, 104.9, 126.5, 127.4, 132.1, 132.2,

133.2, 139.9, 141.6, 141.8, 142.3 ppm. UV/Vis (CH₂Cl₂): λ (log ε)

= 413 (5.73), 530 (4.54), 565(4.11) nm.

5,15-Diphenyl-10-(spirobis-1,3-dithian-2-yl)porphyrin (11a): Spiro-

bisdithiane (1.08 g, 4.84 mmol) was dried in vacuo in a septum-

equipped Schlenk flask for 30 min. Dry THF (20 mL) was then

added under an atmosphere of argon, and the suspension was co-

oled to –40 °C. n-Butyllithium (2.5 , 1.92 mL, 4.84 mmol) was

added dropwise by syringe through the septum, and the reaction

mixture was stirred for 2 h at –25 °C. The solution of the organo-

metallic compound was cooled to –78 °C and mixed with a suspen-

sion (–30 °C) of 5,15-diphenylporphyrin 1a (100 mg, 0.22 mmol)

in dry THF (20 mL). After transfer of the porphyrin suspension,

N,N,NЈ,NЈ-tetramethylethylenediamine (0.2 mL, 1.6 mmol) was

added, and the reaction mixture turned dark brown. After stirring

for 15 min, the cold bath was removed, and the reaction mixture

was stirred for 1 h at room temp. Upon the addition of water

(3 mL), the reaction mixture changed its colour to dark green. The

mixture was stirred for 15 min at room temp., followed by the ad-

dition of a solution of DDQ (0.3 g, ca. 0.75 mmol) in THF

(10 mL), and the colour of the solution changed from green to

purple. Stirring was continued for a further 15 min, and the organic

solvent was removed under reduced pressure. Final purification was

achieved by column chromatography (EtOAc/C₆H₁₄, 1:20) in the

dark to yield the title compound (33 mg, 0.05 mmol, 22%) as a

purple solid. M.p. Ͼ310 °C. R_f= 0.76 (CH₂Cl₂/C₆H₁₄, 2:1). ¹H

NMR (400 MHz, CDCl₃, 20 °C): δ = –3.04 (s, 2 H, NH), 3.38 (d,

J = 14.7 Hz, 2 H, S–CH₂–S), 3.65 (m, 8 H, S–CH₂), 7.71 (s, 1 H,

S–CH–S), 7.76 (m, 6 H, Ar_H), 8.18 (d, J = 6.4 Hz, 4 H, Ar_H), 8.92

(dd, J = 4.7 Hz, 4 H, H_β), 9.25 (d, J = 4.7 Hz, 2 H, H_β), 9.53 (s, 1

H, H_β), 10.13 (s, 1 H, H_meso), 10.55 (s, 1 H, H_β) ppm. ¹³C NMR

(100 MHz, CDCl₃, 20 °C): δ = 24.0, 31.8, 35.1, 41.5, 55.0, 105.5,

112.7, 126.3, 127.4, 134.2, 141.4 ppm. UV/Vis (CH₂Cl₂): λ (log ε)

= 415 (4.42), 511 (3.54), 549 (3.39), 586 (3.42), 638 (3.34) nm.

HRMS (ES+): calcd. for C₃₉H₃₂N₄S₄[M + H]⁺685.1588; found

685.1578.

{5,15-Bis[3-methoxyphenyl-10-(1,3,5-trithian-2-yl)]porphyrinato}-

nickel(II) (6c): The reaction was performed wit the use of the same

conditions as for free base 6a by using 1,3,5-trithiane (0.53 g,

3.80 mmol), n-butyllithium (2.5 , 1.51 mL, 3.80 mmol) and [5,15-

bis(3-methoxyphenyl)porphyrinato]nickel(II) 1d (100 mg,

0.17 mmol). Elution with CH₂Cl₂/C₆H₁₄(1:1) yielded the title com-

pound as a red solid (42 mg, 0.06 mmol, 34%). M.p. Ͼ310 °C. R_f

1

= 0.74 (CH₂Cl₂/C₆H₁₄, 3:1). H NMR (400 MHz, CDCl₃, 20 °C):

δ = 3.92 (s, 6 H, OCH₃), 4.29 (d, J = 15.2 Hz, 2 H, S–CH₂–S), 4.90

(d, J = 14.6 Hz, 2 H, S–CH₂–S), 7.29 (s, 1 H, S–CH–S), 7.50 (s, 2

H, Ar_H), 7.57 (d, J = 5.3 Hz, 6 H, Ar_H), 8.81 (m, 4 H, H_β), 9.00

(d, J = 4.6 Hz, 2 H, H_β), 9.63 (s, 1 H, H_meso), 9.74 (s, 2 H, H_β)

ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = 26.67, 29.28, 30.61,

40.31, 55.00, 55.90, 61.60, 104.87, 111.41, 113.15, 117.94, 119.15,

123.44, 126.23, 127.39, 132.15, 141.24, 141.87, 157.69 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 413 (5.05), 531 (4.23), 574 (4.17) nm.

[5,15-Dihexyl-10-(1,3,5-trithian-2-yl)porphyrinato]nickel(II) (6d):

The reaction was performed with the use of the same conditions

as for free base 6a by using 1,3,5-trithiane (0.57 g, 4.11 mmol), n-

butyllithium (2.5 , 1.63 mL, 4.11 mmol) and (5,15-dihexylporphy-

rinato)nickel(II) (100 mg, 0.19 mmol). Elution with CH₂Cl₂/C₆H₁₄

(1:1) gave the title compound as a red solid (31 mg, 0.05 mmol,

24%). M.p. Ͼ310 °C. R_f= 0.88 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR

(400 MHz, CDCl₃, 20 °C): δ = 0.88 (t, J = 7.0 Hz, 3 H, 5⁶-CH₃),

1.30 (m, 2 H, 5⁵-CH₂), 1.51 (m, 2 H, 5⁴-CH₂), 2.12 (m, 2 H, 5³-

CH₂), 2.20 (m, 2 H, 5²-CH₂), 4.38 (t, J = 14.6 Hz, 2 H, S–CH₂–S),

4.26 (t, J = 7.6 Hz, 2 H, 5¹-CH₂), 4.80 (t, J = 14.6 Hz, 2 H, S–

CH₂–S), 7.10 (s, 1 H, S–CH–S), 9.08 (d, J = 4.7 Hz, 2 H, H_β), 9.15

(m, 4 H, H_β), 9.36 (s, 1 H, H_meso), 9.52 (s, 2 H, H_β) ppm. ¹³C NMR

(100 MHz, CDCl₃, 20 °C): δ = 13.71, 19.00, 22.22, 29.57, 31.31,

33.45, 36.96, 40.23, 55.71, 103.78, 108.93, 110.03, 112.84, 117.46,

128.98, 129.29, 132.18, 140.35, 141.12, 142.00 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 418 (5.53), 539 (4.65), 576 (4.52) nm.

[5,15-Diphenyl-10-(spirobis-1,3-dithian-2-yl)porphyrinato]nickel(II)

(11b): The reaction was performed with the use of the same condi-

tions as given for free base 11a by using spirobisdithiane (0.89 g,

4.01 mmol), n-butyllithium (2.5 , 1.59 mL, 4.0 mmol) and (5,15-

diphenylporphyrinato)nickel(II) 1b (100 mg, 0.18 mmol). The mix-

ture was purified by column chromatography (CH₂Cl₂/C₆H₁₄, 1:1)

and yielded the title compound (45 mg, 0.06 mmol, 33%) as a red

solid. M.p. Ͼ310 °C. R_f= 0.82 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR

(400 MHz, CDCl₃, 20 °C): δ = 3.31 (d, J = 14.0 Hz, 2 H, S–CH₂–

S), 3.67 (m, 8 H, S–CH₂), 7.08 (s, 1 H, S–CH–S), 7.68 (m, 6 H,

Ar_H), 7.95 (d, J = 6.4 Hz, 4 H, Ar_H), 8.77 (m, J = 4.7 Hz, 4 H,

H_β), 9.02 (d, J = 4.7 Hz, 2 H, H_β), 9.66 (s, 1 H, H_meso), 9.77 (s, 2

H, H_β) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = 22.3, 27.4,

2,8-Diformylspirobisdithiane (9): Spirobisdithiane 8 (1.00 g,

4.40 mmol) was dried in vacuo in a septum-equipped Schlenk flask

for 30 min. Dry THF (25 mL) was then added under an atmo-

sphere of argon, and the suspension was cooled to –78 °C. n-Butyl-

Eur. J. Org. Chem. 2007, 3833–3848

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3841

K. Dahms, M. O. Senge, M. B. Bakar

FULL PAPER

29.3, 36.7, 52.8, 104.8, 126.7, 127.4, 132.1, 132.4, 133.2, 140.0,

After 40 min, the reaction was terminated by the addition of

141.5, 141.8, 142.2 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 413 (5.52), NaOH (0.1 , 16.7 mL). The solution was washed several times

530 (4.34), 569 (3.84) nm.

with water, and the solvent was removed under reduced pressure

to yield a yellow oil as the crude product. Column chromatography

(silica, C₆H₁₄/CH₂Cl₂, 1:2, 1% NEt₃) followed by recrystallisation

from C₆H₁₄yielded a white solid (2.54 g, 9.62 mmol, 96%). M.p.

51 °C. ¹H NMR (270 MHz, CDCl₃, 47 °C): δ = 1.86 (m, 1 H, CH₂–

CH_2eq–CH₂), 2.10 (m, 1 H, CH₂–CH_2ax–CH₂), 2.90 (m, 4 H, S–

CH₂), 4.52 (d, J = 4.41 Hz, 1 H, C–CH–C), 4.66 (d, J = 4.41 Hz,

1 H, S–CH–S), 6.11 (m, 2 H, CH–CH=CH), 6.19 (m, 2 H, N–CH),

6.71 (m, 2 H, N–CH=CH), 8.49 (br. s, 2 H, NH) ppm. ¹³C NMR

(126 MHz, CDCl₃, 320 K): δ = 25.49, 31.15, 43.24, 53.37, 107.92,

108.18, 117.40, 129.52 ppm. MS (200 °C, 80 eV): m/z (%) = 264

(77) [M]^·+, 145 (100) [M – C₄H₇S₂]^·+, 119 (80) [M – C₉H₉N₂]^·+.

HRMS: calcd. for C₁₃H₁₆N₂S₂264.07549; found 264.077553.

C₁₃H₁₆N₂S₂(264.40): calcd. C 59.05, H 6.10, N 10.59; found C

59.35, H 6.27, N 10.32.

[5,15-Bis(3-methoxyphenyl)-10-(spirobis-1,3-dithian-2-yl)porphyrin-

ato]nickel(II) (11c): The reaction was performed with the use of the

same conditions as given for the free base 11a by using spirobisdi-

thiane (0.85 g, 3.81 mmol), n-butyllithium (2.5 , 1.51 mL,

3.81 mmol) and [5,15-bis(3-methoxyphenyl)porphyrinato]nickel(II)

1d (100 mg, 0.17 mmol). The mixture was purified by column

chromatography (CH₂Cl₂/C₆H₁₄, 1:1) and yielded the title com-

pound (47 mg, 0.06 mmol, 34%) as a red solid. M.p. Ͼ310 °C. R_f

3

1

= 0.45 (CH₂Cl₂/C₆H₁₄, 3:1). H NMR (400 MHz, CDCl₃, 20 °C):

δ = 3.33 (d, J = 14.0 Hz, 2 H, S–CH₂–S), 3.74 (m, 8 H, S–CH₂),

3.92 (s, 6 H, OCH₃), 7.09 (s, 1 H, S–CH–S), 7.57 (m, 8 H, Ar_H),

8.82 (m, 4 H, H_β), 9.03 (d, J = 4.1 Hz, 2 H, H_β), 9.67 (s, 1 H,

H_meso), 9.77 (s, 2 H, H_β) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C):

δ = 22.27, 29.27, 31.62, 38.07, 55.00, 104.76, 113.15, 119.14, 126.24,

127.37, 130.46, 132.10, 140.49, 141.28, 141.31, 141.85, 157.68 ppm.

UV/Vis (CH₂Cl₂): λ (log ε) = 414 (4.96), 530 (3.78), 567 (3.48) nm.

5,10-Bis(1,3-dithian-2-yl)porphyrin (14a): A solution of tripyrrane

(464 mg, 2.06 mmol), pyrrole (143 µL, 2.06 mmol) and 2-formyl-

1,3-dithiane 12 (611 mg, 4.12 mmol) in CH₂Cl₂(100 mL) was

stirred under an atmosphere of argon with exclusion from light for

45 min followed by the addition of TFA (100 µL). After 16 h of

stirring at room temp., DDQ (1.5 g) was added, and the solution

was stirred for 1 h. The solution was filtered through a plug of silica

gel with CH₂Cl₂containing 1% NEt₃. The residue was purified by

column chromatography on (silica, CH₂Cl₂/C₆H₁₄, 2:1, 1% NEt₃).

Three fractions were collected; the first one was not characterised

because of the small amount. The second fraction contained por-

phin, and the desired compound was collected as last fraction as a

[5,15-Dihexyl-10-(spirobis-1,3-dithian-2-yl)porphyrinato]nickel(II)

(11d): The reaction was performed with the use of the same condi-

tions as given for free base 11a by using spirobisdithiane (0.92 g,

4.11 mmol), n-butyllithium (2.5 , 1.63 mL, 4.11 mmol) and (5,15-

dihexylporphyrinato)nickel(II) (100 mg, 0.19 mmol). The mixture

was purified by column chromatography (CH₂Cl₂/C₆H₁₄, 1:1) and

yielded the title compound (28 mg, 0.02 mmol, 19%) as a red solid.

M.p. Ͼ310 °C. R_f= 0.67 (CH₂Cl₂/C₆H₁₄, 3:1). ¹H NMR

(400 MHz, CDCl₃, 20 °C): δ = 0.91 (t, J = 7.0 Hz, 3 H, 5⁶-CH₃),

1.32 (m, 2 H, 5⁵-CH₂), 1.34 (m, 2 H, 5⁴-CH₂), 1.58 (m, 2 H, 5³-

CH₂), 2.27 (m, 2 H, 5²-CH₂), 3.26 (d, J = 14.0 Hz, 2 H, S–CH₂– mixture of 5,10- 14a and 5,15-bis(1,3-dithian-2-yl)-porphyrin 14b.

S), 4.49 (t, J = 7.6 Hz, 2 H, 5¹-CH₂), 4.80 (m, 8 H, S–CH₂), 6.95

The separation was carried out by a second column chromatog-

(s, 1 H, S–CH–S), 9.03 (d, J = 4.7 Hz, 2 H, H_β), 9.26 (dd, J = raphy on alumina. The desired product was obtained as the second

5.28 Hz, 4 H, H_β), 9.45 (s, 1 H, H_meso), 9.75 (s, 2 H, H_β) ppm. ¹³C fraction as purple crystals (22.5 mg, 41.2 µmol, 3.0 %). M.p.

1

NMR (100 MHz, CDCl₃, 20 °C): δ = 13.79, 22.28, 23.83, 24.31, Ͼ297 °C. H NMR (270 MHz, CDCl₃, 20 °C): δ = –3.52 (br. s, 2

29.66, 31.34, 33.56, 35.11, 37.14, 38.80, 41.51, 43.39, 53.14, 103.77,

H, NH), 2.53 (m, 4 H, CH₂–CH₂–CH₂), 3.34 (m, 4 H, S–CH_2eq),

117.51, 120.92, 129.40, 129.70, 132.24, 139.28, 140.64, 141.04, 3.70 (m, 4 H, S–CH_2ax), 7.87 (s, 2 H, S–CH–S), 9.40 (m, 4 H,

141.95 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 416 (4.98), 535 (3.70), 2,13,17,18-H_β), 9.74 (br. s, 2 H, 3,12-H_β), 10.10 (s, 2 H, 15,20-

568 (3.48) nm.

H_meso), 10.70 (br. s, 2 H, 7,8-H_β) ppm. UV/Vis (CH₂Cl₂): λ (log ε)

= 413 (5.34), 510 (4.23), 546 (3.79), 582 (3.82), 633 (3.43) nm. MS

(FAB+, 3 KV): m/z (%) = 547.0 (10) [M + H]^·+, 427.0 (2) [M –

C₄H₇S₂+H]⁺.

[5-Hexyl-10,20-diphenyl-15-(spirobis-1,3-dithian-2-yl)porphyrinato]-

nickel(II) (11e): The reaction was performed with the use of the

same conditions as given for free base 11a by using spirobisdithiane

(0.82 g, 3.65 mmol), n-butyllithium (2.5 , 1.45 mL, 3.65 mmol)

and (5-hexyl-10,20-diphenylporphyrinato)nickel(II)^[17c,34](100 mg,

0.17 mmol). The mixture was purified by column chromatography

(CH₂Cl₂/C₆H₁₄, 2:1) and yielded the title compound (54 mg,

0.06 mmol, 40%) as a red solid. M.p. Ͼ310 °C. R_f= 0.78 (CH₂Cl₂/

5,15-Bis(1,3-dithian-2-yl)porphyrin (14b): 2-Formyl-1,3-dithiane 12

(100 mg, 0.67 mmol) and dipyrromethane (100 mg, 0.67 mmol)

were dissolved in CH₂Cl₂(170 mL). After purging with argon TFA

(10 µL) was added, and the mixture was stirred for 14 h. Then,

DDQ (390 mg, 1.7 mmol) was added, and the mixture was heated

for 10 min under reflux. The crude mixture was filtered through

silica gel, concentrated under reduced pressure and subjected to

column chromatography (silica, CH₂Cl₂/C₆H₁₄,1:2) to yield the title

compound as a purple solid (300 mg, 0.55 mmol, 16.0 %). M.p.

1

C₆H₁₄, 3:1). H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.85 (t, J =

7.6 Hz, 3 H, 5⁶-CH₃), 1.36 (m, 2 H, 5⁵-CH₂), 1.55 (m, 2 H, 5⁴-

CH₂), 2.39 (m, 2 H, 5³-CH₂), 2.61 (m, 2 H, 5²-CH₂), 3.14 (d, J =

14.6 Hz, 2 H, S–CH₂–S), 3.59 (m, 8 H, S–CH₂), 4.46 (t, J = 7.6 Hz,

2 H, 5¹-CH₂), 6.88 (s, 1 H, S–CH–S), 7.65 (m, 6 H, Ar_H), 7.91 (d,

J = 6.4 Hz, 4 H, Ar_H), 8.67 (dd, J = 4.7 Hz, 4 H, H_β), 9.18 (d, J

= 4.7 Hz, 2 H, H_β), 9.62 (s, 2 H, H_β) ppm. ¹³C NMR (100 MHz,

CDCl₃, 20 °C): δ = 13.70, 22.19, 23.76, 24.29, 29.29, 31.60, 33.64,

36.94, 38.00, 52.85, 109.62, 118.01, 119.57, 126.49, 127.33, 129.58,

132.00, 132.47, 133.14, 139.92, 140.66, 140.77, 141.3917,

141.5077 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 421 (4.95), 539 (4.01),

577 (3.79) nm.

1

Ͼ320 °C. H NMR (270 MHz, CDCl₃, 20 °C): δ = –2.75 (br. s, 2

H, NH), 2.45 (m, 4 H, CH₂–CH₂–CH₂), 3.38 (m, 4 H, S–CH_2eq),

3.67 (m, 4 H, S–CH_2ax), 7.76 (s, 2 H, S–CH-S), 9.37 (AB, ³J =

4.41 Hz, 4 H, 2,8,12,18-H_β), 10.20 (s, 2 H, 10,20-H_meso), 9.71 +

10.55 (2 br. s, 4 H, 3,7,13,17-H_β) ppm. UV/Vis (CH₂Cl₂): λ (log ε)

= 410 (4.95), 509 (3.82), 545 (3.65), 578 (3.46), 638 (3.30) nm. MS

(305 °C, 80 eV): m/z (%) = 546 (100) [M]^·+, 442 (30) [M –

C₃H₇S₂+H]⁺, 273 (5) [M]²⁺. HRMS: calcd. for C₂₈H₂₆N₄S₄

546.10403; found 546.10500. C₂₈H₂₆N₄S₄(546.78): calcd. C 61.51,

H 4.79, N 10.25; found C 61.31, H 5.01, N 10.23. Ϫ Reaction of 13

with trimethylorthoformate and trichloroacetic acid gave the same

product in 3% yield.

5-(1,3-Dithian-2-yl)dipyrromethane (13): A mixture of 2-formyl-1,3-

dithiane 12 (1.48 g, 10 mmol) and pyrrole (400 mL) was purged

with argon for 10 min, followed by the addition of BF₃·Et₂O

(500 µL). After 20 min, the same amount of acid was added again.

3842

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Eur. J. Org. Chem. 2007, 3833–3848

Exploration of meso-Substituted Formylporphyrins

FULL PAPER

5,10,15-Tris(1,3-dithian-2-yl)porphyrin (14c): 2-Formyl-1,3-dithiane

12 (100 mg, 0.67 mmol) and pyrrole (50 µL) were dissolved in

CH₂Cl₂(100 mL). After purging with argon, BF₃·OEt₂(10 µL) was

added, and the mixture was stirred for 1 h. The crude mixture was

filtered through silica and concentrated under reduced pressure to

yield a purple solid that was stored under Ar at –20 °C. Yield:

230 mg (308 mmol, 46 %). M.p. 224 °C. ¹H NMR (500 MHz,

CDCl₃, 47 °C): δ = –2.76 (br. s, 2 H, NH), 2.53 (m, 3 H, CH₂–

form (25 mL). The reaction mixture was stirred vigorously for

30 min. The organic phase was then washed with a NaHCO₃solu-

tion and water. The residue was purified by column chromatog-

raphy (basic alumina grade III, CHCl₃/C₆H₁₄, 2:1) to yield purple

crystals (10.0 mg, 0.023 mmol, 30%). M.p. Ͼ 320 °C. ¹H NMR

(270 MHz, CD₂Cl₂, 47 °C): δ = –2.92 (m, 2 H, NH), 1.42 (m, 6 H,

CH₃), 3.92 (m, 2 H, O–CH₂), 4.33 (m, 2 H, O–CH₂), 7.77 (s, 1 H,

3

O–CH–O), 9.14 (AB, ³J = 4.55 Hz, 2 H, 13,17-H_β), 9.28 (AB, J =

CH_2eq–CH₂), 2.89 (m, 3 H, CH₂–CH_2ax–CH₂), 3.29 (m, 6 H, S– 4.55 Hz, 2 H, 3,7-H_β), 9.75 (AB, ³J = 4.55 Hz, 2 H, 12,18-H_β), 9.93

3

CH_2eq), 3.59 (m, 6 H, S–CH_2ax), 7.66 (s, 2 H, S–CH–S), 7.74 (s, 1 (AB, J = 4.55 Hz, 2 H, 2,8-H_β), 9.94 (s, 2 H, 10,20-H_meso), 12.11

H, S–CH–S), 9.24 (d, ³J = 4.41 Hz, 2 H, 2,18-H_β), 9.98 (s, 1 H,

(s, 1 H, CHO) ppm. ¹³C NMR (500 MHz, CD₂Cl₂, 0 °C): δ =

H_meso), 9.34 + 10.64 (br. s, 6 H, 3,7,8,12,13,17-H_β) ppm. UV/Vis 15.44, 64.63, 105.07, 106.61, 107.11, 119.19, 128.18, 130.28, 131.85,

(CH₂Cl₂): λ (log ε) = 423 (5.16), 520 (4.07), 555 (3.55), 595 (3.64), 134.01, 143.64, 145.38, 145.96, 148.91, 193.65 ppm. UV/Vis

652 (3.15) nm. MS (FAB+, 3 KV): m/z (%) = 665 (19) [M + H]⁺, (CH₂Cl₂): λ (log ε) = 410 (5.10), 514 (3.71), 555 (3.94), 583 (3.62),

664 (40) [M]^·+, 663 (24) [M – H]⁺, 590 (5) [M – C₃H₆S]⁺.

C₃₂H₃₂N₄S₆(664.99): calcd. C 57.80, H 4.85, N 8.43; found C

57.41, H 4.82, N 8.32. Ϫ Alternatively, this compound could be

prepared by the reaction of 12 and 13 and BF₃·OEt₂catalysis in a

similar yield.

641 (3.82), 670 (3.40) nm. MS (FAB+): m/z (%) = 441 (100) [M]^·+,

367 (50) [C₄H₁₀O]⁺. HRMS: calcd. for C₂₆H₂₄N₄O₃440.18484;

found 440.18500.

5-(1,3-Dithian-2-yl)-10,15,20-triphenylporphyrin (16a) and 5,15-

Bis(1,3-dithian-2-yl)-10,20-diphenylporphyrin (16b): A solution of 2-

formyl-1,3-dithiane 12 (1.0 g, 6.7 mmol) and 5-phenyldipyrrome-

thane (1.49 g, 6.7 mmol) in dry CH₂Cl₂(1.7 L) was purged with

argon. After 1 h, a catalytic amount of TFA (110 µL) was added,

followed by stirring at room temp. for 1 h. After the addition of

DDQ (3.9 g, 17.2 mmol), the mixture was oxidised in the air for

45 min. The crude mixture was filtered through silica gel, eluting

with CH₂Cl₂. Column chromatography (silica, CH₂Cl₂/C₆H₁₄, 2:1)

eluted first 16a, followed by 16b. Analytical data for 16a: Yield:

70 mg (0.11 mmol, 3.0 %) of a purple solid. M.p. Ͼ320 °C. ¹H

NMR (250 MHz, CDCl₃, 20 °C): δ = –2.65 (br. s, 2 H, NH), 2.50

(m, 2 H, CH₂–CH₂–CH₂), 3.28 (m, 2 H, S–CH_2eq), 3.61 (m, 2 H,

S–CH_2ax), 7.72 (s, 1 H, S–CH–S), 7.77 (m, 9 H, Ar_m,p-H), 8.20 (m,

6 H, Ar_o-H), 8.79 (m, 4 H, 12,13,17,18-H_β), 8.92 (AB, ³J = 4.41 Hz,

2 H, 2,8-H_β), 10.02 (m, 2 H, 3,7-H_β) ppm. ¹³C NMR (126 MHz,

CDCl₃, 20 °C): δ = 26.17, 35.76, 54.06, 114.05, 120.32, 121.19,

126.61, 126.74, 127.75, 131.17, 134.49, 141.73, 142.29 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 424 (5.41), 518 (4.24), 552 (3.83), 593 (3.74),

650 (3.57) nm. MS (FAB+, 3 kV): m/z (%) = 657 (100) [M + H]⁺,

656 (73) [M]^·+, 580 (37) [M – C₆H₅+H]^·+, 503 (28) [M – 2C₆H₅+

H]⁺. HRMS: calcd. for C₄₂H₃₂N₄S₂656.20684; found 656.20434.

5,10,15,20-Tetrakis(1,3-dithian-2-yl)porphyrin (14d): 2-Formyl-1,3-

dithiane 12 (1 g, 6.70 mmol) and pyrrole (500 µL, 6.90 mmol) were

dissolved in CH₂Cl₂(200 mL) in a 250-mL Schlenk flask and

purged with argon. BF₃·OEt₂(40 µL) was added, and the mixture

was stirred for 1 h under an atmosphere of Ar. After 1 h, DDQ

(250 mg, 1.10 mmol) was added, which was followed by stirring for

20 min, the addition of NEt₃(100 µL) and again stirring for

20 min. The crude mixture was concentrated to 200 mL and filtered

through basic alumina, washing with CH₂Cl₂(containing 1 %

NEt₃) followed by column chromatography (basic alumina,

CH₂Cl₂/C₆H₁₄, 2:1 + 1% NEt₃) to yield 700 mg (0.89 mmol, 53%)

of 5,10,15,20-tetrakis(1,3-dithinanyl)porphyrinogen. A solution of

this porphyrinogen (50 mg) in CH₂Cl₂(100 mL + 1 drop NEt₃) was

treated with DDQ (50 mg, 0.22 mmol) over 4 min and after 5 min

filtered through basic alumina with CH₂Cl₂. The solvent was evap-

orated, and the product was dried under high vacuum. The purple-

red solid was stored under an atmosphere of argon at –20 °C. Yield:

20 mg (0.026 mmol, 30% with respect to the crude intermediate,

15 % with respect to 2-formyl-1,3-dithiane). M.p. Ͼ320 °C. ¹H

NMR (500 MHz, CDCl₃, 47 °C): δ = –2.42 (br. s, 2 H, NH), 2.48

(m, 8 H, CH₂–CH₂–CH₂), 3.61–3.25 (m, 16 H, S–CH₂), 7.54 (s, 4

H, S–CH–S), 9.97 (br. s, 8 H, H_β) ppm. UV/Vis (CH₂Cl₂): λ (log

ε) = 433 (4.42), 527 (3.36), 565 (3.05), 601 (3.02), 664 (2.58) nm.

MS (FAB+, 3 kV): m/z (%) = 783 (10) [M + H]⁺, 665 (15) [M –

C₄H₇S₂]⁺. C₃₆H₃₈N₄S₈(783.20): calcd. C 55.21, H 4.89, N 7.15;

found C 55.62, H 4.97, N 7.44.

C

₄₂H₃₂N₄S₂(656.86): calcd. C 76.80, H 4.91, N 8.53; found C

76.95, H 5.21, N 8.88. Analytical data for 16b: Yield: 40 mg

(0.057 mmol, 2 %) of a purple solid. M.p. Ͼ320 °C. ¹H NMR

(270 MHz, CDCl₃, 47 °C): δ = –2.59 (br. s, 2 H, N–H), 2.47 (m, 4

H, CH₂–CH₂–CH₂), 3.27 (m, 2 H, S–CH_2eq), 3.60 (m, 2 H, S–

CH_2ax), 7.69 (s, 2 H, S–CH–S), 7.75 (m, 6 H, Ar_m,p-H), 8.14 (m, 4

3

H, Ar_o-H), 8.78 (AB, J = 5.15 Hz, 4 H, 2,8,12,18-H_β), 9.90 (br. s,

5-Formylporphyrin (15a):^[30]A solution of 5,15-bis(1,3-dithian-2-

yl)porphyrin 5 (40 mg, 72.0 µmol) in chloroform (30 mL) was

treated with bis(trifluoracetoxy)iodobenzene (260 mg, 600 µmol).

The mixture was stirred for 30 min at 45 °C. The solution was

washed several times with a solution of NaHCO₃and water, dried,

and subjected to column chromatography (basic alumina grade III,

CHCl₃/C₆H₁₄, 3:1). Yield: 15.0 mg (45 µmol, 61.7%) of a purple

solid. M.p. Ͼ320 °C. ¹H NMR (270 MHz, CD₂Cl₂, 47 °C): δ =

–3.27 (br. s, 2 H, N-H), 9.39 (AB, ³J = 4.55 Hz, 2 H, H_β), 9.43

(AB, ³J = 4.55 Hz, 2 H, H_β), 9.51 (AB, ³J = 4.55 Hz, 2 H, H_β),

4 H, 3,7,13,17-H_β) ppm. ¹³C NMR (126 MHz, CDCl₃, 47 °C): δ =

26.17, 35.72, 53.75, 115.06, 120.42, 126.57, 127.81, 130.06, 134.43,

142.37, 146.32 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 422.76 (5.31),

521.31 (4.24), 555.70 (3.92), 598.22 (3.78), 653.70 (3.71) nm. MS

(FAB+, 3 kV): m/z (%) = 699 (100), [M + H]⁺, 698 (73 [M]^·+

.

HRMS: calcd. for C₄₀H₃₄N₄S₄698.166635; found 698.16437.

C₄₀H₃₄N₄S₄(698.98): calcd. C 68.73, H 8.02, N 4.90; found C

68.52, H 8.25, N 4.77. Crystal data: (grown from CH₂Cl₂/MeOH

by using standard techniques):^[21,44,45]C₄₀H₃₄N₄S₄, M = 698.99,

monoclinic, a = 6.6701(7) Å, b = 12.0093(16) Å, c = 21.684(3) Å,

β = 92.974(9)°, V = 1734.6(4) Å³, T = 210 K, space group P2₁c, Z

= 2, µ(Mo-K_α) = 0.31 mm^–1, 10886 reflections measured, 3043

unique (R_int= 0.0995) which were used in all calculations. Final

R₁(F²) was 0.0581 [F Ͼ 4.0σ(F)] and wR(F²) was 0.116 (all data).

3

10.15 (AB, J = 5.47 Hz, 2 H, H_β), 10.28 (s, 3 H, 10,15,20-H_meso),

12.51 (s, 1 H, CHO) ppm. MS (FAB+): m/z (%) = 339.0 (80) [M +

H]⁺.

5-Diethoxymethyl-15-formylporphyrin (15b): A solution of 5,15-

bis(1,3-dithian-2-yl)porphyrin 14b (40 mg, 72.0 µmol) in chloro-

form (30 mL, Merck, techn.) was treated dropwise with a solution

of bis(trifluoracetoxy)iodobenzene (130 mg, 302 µmol) in chloro-

5-Formyl-10,15,20-triphenylporphyrin (17a): The compound was

prepared from 16a by using procedure B described above. Yield:

1

33 mg of a purple solid (58 µmol, 97%). M.p. Ͼ300 °C. H NMR

Eur. J. Org. Chem. 2007, 3833–3848

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3843

K. Dahms, M. O. Senge, M. B. Bakar

FULL PAPER

(270 MHz, CDCl₃, 48 °C): δ = –2.01 (br. s, 2 H, NH), 7.76 (m, 9

[5-Formyl-10,20-bis(3-methoxyphenyl)porphyrinato]copper(II) (20a):

Prepared by reaction of 19a following procedure C. After column

H, Ph_m,p-H), 8.15 (m, 6 H, Ar_o-H), 8.67 (AB, ³J = 4.14 Hz, 2 H,

3

H_β), 8.74 (AB, J = 5.15 Hz, 2 H, H_β), 8.96 (AB, J = 5.15 Hz, 2 chromatography (h = 43 cm, ø = 3 cm, alumina, CH₂Cl₂), the first

H, H_β), 9.99 (AB, ³J = 5.15 Hz, 2 H, H_β), 12.46 (s, 1 H, CHO) fraction containing product 2 as dark purple crystals (20.6 mg,

ppm. ¹³C NMR (126 MHz, CDCl₃, 48 °C): δ = 122.76, 126.8,

0.03 mmol, 12.9%) was obtained. M.p. 285 °C. R_f= 0.63 (CH₂Cl₂/

128.08, 128.14, 134.25, 141.44, 141.57, 153.62 ppm. UV/Vis C₆H₁₄, 2:1). UV/Vis (CH₂Cl₂): λ (log ε) = 418 (5.42), 548 (4.33),

(CH₂Cl₂): λ (log ε) = 424 (5.30), 527 (4.05), 568 (4.09), 597 (3.81), 592 (4.51) nm. MS (ES): m/z (%) = 612 (35) [M]^·+, 551 (87)

653 (3.91) nm. MS (280 °C, 80 eV): m/z (%) = 566 (100) [M]^·+, 283

[(⁶³CuM) – OCH₃– CHO]⁺, 267 (5) [M]²⁺

.

(13) [M]²⁺. HRMS: calcd. for C₃₉H₂₆N₄O 566.2107; found 566.10.

[5,15-Diformyl-10,20-bis(3-methoxyphenyl)porphyrinato]copper(II)

(20b): This compound was obtained as a second product from the

reaction to prepare 20a. After column chromatography (h = 43 cm,

ø = 3 cm, alumina, CH₂Cl₂), the second fraction contained product

20b as dark green crystals (32.5 mg, 0.05 mmol, 20 %). M.p.

Ͼ310 °C. R_f= 0.28 (CH₂Cl₂/C₆H₁₄, 2:1). UV/Vis (CH₂Cl₂): λ (log

ε) = 432 (4.89), 628 (4.03) nm. MS (ES): m/z (%) = 611 (5) [M –

CHO]⁺.

5,15-Diformyl-10,20-diphenylporphyrin (17b): The compound was

prepared from 16b by using procedure B given above. Yield:

28.5 mg of a purple solid (55 µmol, 96%). M.p. 301 °C. H NMR

1

(270 MHz, CDCl₃, 47 °C): δ = –1.98 (br. s, 2 H, NH), 7.78 (m, 6

H, Ar_m,p-H), 8.17 (m, 4 H, Ar_o-H), 8.69 (AB, ³J = 5.15 Hz, 2 H,

3

H_β), 8.77 (AB, J = 5.15 Hz, 2 H, H_β), 8.98 (AB, J = 5.15 Hz, 2

H, H_β), 10.01 (AB, ³J = 5.15 Hz, 2 H, H_β), 12.48 (s, 2 H, CHO)

ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 424 (4.99), 527 (3.93), 568

(3.88), 597 (3.74), 654 (3.70) nm. MS (280 °C, 80 eV): m/z (%) =

518 (100) [M]^·+, 259 (9) [M]²⁺. HRMS: calcd. for C₃₄H₂₂N₄O₂

518.17428; found 518.17431. C₃₄H₂₂N₄O₂(518.57): calcd. C 78.75,

H 4.28, N 10.80; found C 78.81, H 4.37, N 10.68.

[5,15-Diformyl-10,20-bis(3-methoxyphenyl)porphyrinato]nickel(II)

(20c): Prepared by reaction of 1d following procedure C. After col-

umn chromatography (h = 34 cm, ø = 3 cm, silica, CH₂Cl₂), the

second fraction contained 20c as dark green crystals (52.4 mg,

0.08 mmol, 47.7%). M.p. 254 °C. R_f= 0.3 (CH₂Cl₂/C₆H₁₄, 2:1). ¹H

NMR (400 MHz, CDCl₃, 20 °C): δ = 3.98 (s, 6 H, OCH₃), 7.31 (m,

[5-(1,3-Dithian-2-yl)-10,15,20-triphenyl)porphyrinato]zinc(II) (18):

A solution of 5-(1,3-dithian-2-yl)-10,15,20-triphenylporphyrin 16a

(50 mg, 0.08 mmol) in CH₂Cl₂(10 mL) was treated under an atmo-

sphere of argon at room temp. with MeOH (0.5 mL) and zinc ace-

tate (200 mg, 1.09 mmol). The mixture was stirred for 30 min. The

organic phase was then washed with water and dried with sodium

sulfate. After recrystallisation from CH₂Cl₂/MeOH purple crystals

were obtained. Yield: 29 mg (1.43 mmol, 53%). M.p. Ͼ300 °C. R_f

3

2 H), 7.47 (m, 2 H), 7.52 (m, 2 H), 7.62 (m, 2 H), 8.81 (AB, J =

5.11 Hz, 4 H, H_β), 9.73 (AB, ³J = 4.68 Hz, 4 H, H_β), 11.97 (s, 2 H,

CHO) ppm. ¹³C NMR (150 MHz, CDCl₃, 20 °C): δ = 55.36,

108.27, 113.69, 119.42, 121.16, 126.23, 127.98, 131.76, 134.90,

140.22, 142.22, 142.62, 158.14, 192.47, 192.49 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 429 (7.11), 632 (3.85) nm. MS (ES+): m/z (%)

= 635 (8) [M]^+·, 544 (14) [M – OCH₃– OCH₃– CHO]⁺, 317 (11)

[M]²⁺. HRMS (ES+): calcd. for C₃₆H₂₅N₄O₄Ni [M + H]⁺635.1229;

found 635.1245.

1

= 0.57 (CH₂Cl₂/C₆H₁₄, 2:1). H NMR (300 MHz, CDCl₃, 20 °C):

δ = 2.25 (m, 2 H, CH₂–CH₂–CH₂), 3.10 (m, 2 H, S–CH₂), 3.58 (m,

2 H, S–CH₂), 7.75 (m, 10 H, S–CH–S, Ar_o,p-H), 8.15 (m, 6 H,

(5-Formyl-10,20-dihexylporphyrinato)nickel(II) (20d): This com-

pound was obtained as a second product from the reaction to pre-

pare 20c. After column chromatography (h = 34 cm, ø = 3 cm, sil-

ica, CH₂Cl₂), the first fraction contained product 20d as purple

crystals (275 mg, 0.49 mmol, 60 %). M.p. 149 °C. R_f= 0.68

(CH₂Cl₂). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.97 (t, ³J =

7.04 Hz, 6 H, CH₃), 1.38 (m, 8 H, CH₂–CH₃+ CH₂–CH₂–CH₃),

1.53 (m, 4 H, CH₂–CH₂–CH₂–CH₃), 2.09 (m, 4 H, CH₂–CH₂–

CH₂–CH₂–CH₃), 3.85 (t, ³J = 8.10 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–

CH₂–CH₃), 8.52 (AB, ³J = 4.52 Hz, 2 H, H_β), 8.70 (AB, ³J =

3

Ar_m-H), 8.76 (AB, J = 4.6 Hz, 2 H, H_β), 8.82 (AB, J = 4.7 Hz, 2

H, H_β), 8.95 (AB, ³J = 4.7 Hz, 2 H, 2,8-H_β), 9.76 (AB, ³J = 5.0 Hz,

2 H, 3.7-H_β) ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 425 (5.86), 555

(4.30), 600 (3.82) nm. MS (ESI): m/z (%) = 718 (100) [M]^·+. HRMS:

calcd. for C₄₂H₃₀N₄S₂Zn 718.1203; found 718.1170.

Synthesis of Formylporphyrins by the Vilsmeier Reaction

General Procedure C: A 100-mL three-necked flask equipped with

a reflux condenser containing anhydrous DMF (75 equiv.) was

charged dropwise and slowly with POCl₃(74 equiv.) at 0–2 °C un-

der an atmosphere of argon. After 20 min, the POCl₃–DMF com-

plex solidified. After removal of the ice bath, 1,2-dichloroethane

(5 mL) was added, and the solution was heated gently to 50 °C.

The metalloporphyrin (0.1–1.5 g) was added slowly at 50 °C as a

solution in 1,2-dichloroethane (25 mL). After complete addition,

the mixture was heated to reflux for 12 h. After cooling with an ice

bath, a saturated aqueous sodium acetate solution was added very

carefully, and then the mixture was heated to 80 °C for 3 h for

completion of the hydrolysis. After cooling to room temp., the por-

phyrin was extracted into CH₂Cl₂(3ϫ), followed by washing with

water (1ϫ), aqueous sodium hydrogen carbonate (2ϫ) and then

with brine (2ϫ). Finally, the organic phase was dried with anhy-

drous sodium sulfate, and the solvent was evaporated under re-

duced pressure.

3

4.65 Hz, 2 H, H_β), 8.76 (AB, J = 5.18 Hz, 2 H, H_β), 8.83 (s, 1 H,

H_meso), 9.30 (AB, ³J = 5.18 Hz, 2 H, H_β), 11.47 (s, 1 H, CHO)

ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ = 13.76, 22.28,

29.62, 31.24, 33.34, 37.14, 103.76, 106.82, 118.83, 127.86, 129.34,

130.91, 132.17, 139.32, 139.34, 142.04, 142.80, 191.88 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 421 (5.30), 550 (4.19), 594 (4.44) nm. HRMS

(ES+): calcd. for C₃₃H₃₆N₄ONi 562.2243; found 562.2256.

C₃₃H₃₆N₄ONi (563.37): calcd. C 70.36, H 6.44, N 9.95; found C

70.21, H 6.39, N 9.93.

(5,15-Diformyl-10,20-dihexylporphyrinato)nickel(II) (20e): Prepared

by reaction of 10a following procedure C. After column

chromatography (h = 56 cm, ø = 3 cm, silica, CH₂Cl₂), the second

fraction gave product 20e as dark purple crystals (46.4 mg,

0.078 mmol, 41.9%). M.p. 199 °C. R_f= 0.46 (CH₂Cl₂/C₆H₁₄, 2:1).

3

(5-Formyl-10,20-diphenylporphyrinato)nickel(II) (3b): For the

Vilsmeier complex, dry DMF (2.7 mL, 34.7 mmol) and POCl₃

(3.06 mL, 33.4 mmol) were used for the monoformylation of (5,15-

diphenylporphyrinato)nickel(II) 1b (500 mg, 0.96 mmol) following

procedure C. Yield: 308 mg (0.56 mmol, 59%). Full characterisa-

tion was described earlier by the deprotection of dithianylporphyrin

2b.

¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.84 (t, J = 7.04 Hz, 6

H, CH₃), 1.25 (m, 8 H, CH₂–CH₂–CH₃), 1.36 (m, 4 H, CH₂–CH₂–

CH₂–CH₃), 1.86 (m, 4 H, CH₂–CH₂–CH₂–CH₂–CH₃), 4.16 (t, ³J

3

= 7.73 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃), 8.93 (AB, J =

4.68 Hz, 4 H, H_β), 9.38 (AB, ³J = 4.68 Hz, 4 H, H_β), 11.52 (s, 2 H,

CHO) ppm. ¹³C NMR (100 MHz, CDCl₃, 20 °C): δ = 13.58, 22.07,

29.29, 31.09, 33.13, 36.21, 105.97, 120.27, 131.01, 131.45, 140.15,

3844

www.eurjoc.org

Eur. J. Org. Chem. 2007, 3833–3848

Exploration of meso-Substituted Formylporphyrins

FULL PAPER

140.94, 191.36 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 425 (5.11), 622

fied by column chromatography (h = 29 cm, ø = 3 cm, silica,

CH₂Cl₂); the first fraction gave the product as dark red crystals

(15.9 mg, 0.03 mmol, 54%). M.p. 49 °C. R_f= 0.32 (CH₂Cl₂/C₆H₁₄,

1:4). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.91 (t, ³J = 7.27 Hz,

9 H, CH₃), 1.33 (m, 4 H, CH₂-CH₃), 1.41 (m, 4 H, CH₂–CH₂–

CH₃), 1.57 (m, 4 H, CH₂–CH₂–CH₂–CH₃), 2.24 (m, 4 H, CH₂–

CH₂–CH₂–CH₂–CH₃), 4.56 (t, ³J = 8.04 Hz, 4 H, CH₂–CH₂–CH₂–

(3.14) nm. MS (ES+): m/z (%) = 591 (13) [M]^+·, 304 (2) [M]²⁺

.

(5,15-Diformyl-10,20-dihexylporphyrinato)copper(II) (20f): This

compound was obtained as a second product from the reaction

to prepare 20e. The second fraction from column chromatography

(silica, CH₂Cl₂/C₆H₁₄, 2:1) and recrystallisation from CH₂Cl₂/

MeOH gave the product as green crystals (10 mg, 0.02 mmol,

18 %). M.p. 292 °C. R_f= 0.35 (CH₂Cl₂/C₆H₁₄, 2:1). UV/Vis

(CH₂Cl₂): λ (log ε) = 427 (5.16), 572 (3.56), 626 (4.12) nm. MS (EI,

70 eV): m/z = 595 (1) [M]^·+, 298 (1) [M]²⁺. HRMS (ES+): calcd.

for C₃₄H₃₆CuN₄O₂595.2291; found 595.5298.

3

CH₂–CH₂–CH₃), 9.06 (AB, J = 4.21 Hz, 2 H, H_β), 9.32 (AB/AB,

³J = 5.40, ⁴J = 2.16 Hz, 4 H, H_β), 9.36 (AB, ³J = 4.97 Hz, 2 H, H_β),

9.48 (s, 1 H, H_meso) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ

= 8.02, 13.72, 19.52, 22.26, 29.29, 29.65, 29.88, 31.20, 31.36, 33.48,

33.59, 36.94, 37.06, 45.37, 53.01, 102.50, 114.49, 116.83, 125.11,

128.79, 129.13, 129.27, 131.025, 131.68, 135.32, 139.73,

140.25 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 415 (4.88), 532 (3.94)

nm.

(5,15-Diisobutyl-10-formylporphyrinato)copper(II) (20g): Prepared

by reaction of (5,15-diisobutylporphyrinato)copper(II) following

procedure C. The first fraction from column chromatography (sil-

ica, CH₂Cl₂/C₆H₁₄, 2:1) followed by recrystallisation from CH₂Cl₂/

MeOH gave the pure product as purple crystals (12.1 mg,

0.02 mmol) in 47% yield. M.p. Ͼ310 °C. R_f= 0.55 (CH₂Cl₂/C₆H₁₄,

2:1). UV/Vis (CH₂Cl₂): λ (log ε) = 419 (5.98), 550 (3.89), 593 (4.09)

nm. MS (EI, 70 eV): m/z = 511 (13) [M]^·+, 468 (2) [M – C₃H₇]⁺.

HRMS (ESI): calcd. for C₂₉H₂₉CuN₄O [M + H]⁺512.1637; found

512.1631.

[5-(1-Hydroxybenzyl)-10,20-diphenylporphyrinato]nickel(II) (22c):

Compound 3b (100 mg, 0.17 mmol) was dissolved in dry THF and

a solution of phenylmagnesium bromide (1  in THF, 1.7 mL,

1.7 mmol) was added. The reaction mixture was stirred at room

temp. for 12 h. The reaction was quenched with aqueous saturated

ammonium chloride (10 mL). The layers were separated, and the

aqueous layer was extracted with CH₂Cl₂. The organic layer was

washed with water several times. The solvent was evaporated, and

the product was purified by column chromatography (h = 21 cm, ø

= 3 cm, silica, CH₂Cl₂). The first fraction gave the product as dark

purple crystals (99.6 mg, 0.16 mmol, 93%). M.p. 236 °C. R_f= 0.51

[5,15-Bis(1-ethylpropyl)-10-formylporphyrinato]copper(II) (20h):

Prepared by reaction of [5,15-bis(1-ethylpropyl)porphyrinato]cop-

per(II) following procedure C. The second fraction of column

chromatography (silica, CH₂Cl₂/C₆H₁₄, 2:1) followed by recrystalli-

sation from CH₂Cl₂/MeOH gave the pure product as purple crys-

tals (31 mg, 0.06 mmol) in 97 % yield. M.p. 299 °C. R_f= 0.52

(CH₂Cl₂/C₆H₁₄, 2:1). UV/Vis (CH₂Cl₂): λ (log ε) = 429 (5.15), 580

(3.49), 630 (4.14) nm. MS (70 eV): m/z = 541 (2) [M]^·+, 539(3)

[M]^·+, 396 (7) [M – C₁₁H₂₃O]⁺, 71 (26) [C₅H₁₁]⁺.

1

(CH₂Cl₂). H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.91, 7.28 (m,

5 H, Ar_o-H+ CDCl₃), 7.57 (m, 2 H, Ar_H), 7.71 (m, 6 H, Ar_o,p-H),

8.00 (m, 4 H, Ar_m-H), 8.08 (m, 1 H, Ar_p-H), 8.79 (AB, ³J = 5.16 Hz,

2 H, H_β), 8.85 (AB, ³J = 4.85 Hz, 2 H, H_β), 9.12 (AB, ³J = 4.85 Hz,

2 H, H_β), 9.37 (AB, ³J = 5.16 Hz, 2 H, H_β), 9.78 (s, 1 H, H_meso

)

[5-(1-Hydroxypropyl)-10,20-diphenylporphyrinato]nickel(II) (22a):

(5-Formyl-10,20-diphenylporphyrinato)nickel(II) 3b (30 mg,

0.05 mmol) was dissolved in dry THF. A solution of ethylmagne-

sium bromide (3  in Et₂O, 170 µL, 0.5 mmol) was added. The re-

action mixture was stirred at room temp. for 12 h, and the reaction

was quenched with aqueous saturated ammonium chloride

(10 mL). The layers were separated, and the aqueous layer was ex-

tracted with CH₂Cl₂. The organic layer was washed with water sev-

eral times. The solvent was evaporated, and the product was puri-

fied by column chromatography (h = 36 cm, ø = 3 cm, silica,

CH₂Cl₂); the first fraction gave the pure product as dark red crys-

tals (21.6 mg, 0.037 mmol, 68%). M.p. 99 °C. R_f= 0.5 (CH₂Cl₂).

ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ = 74.62, 104.60,

125.88, 126.27, 126.40, 126.47, 127.36, 127.69, 130.26, 132.02,

132.16, 132.72, 133.01, 133.11, 133.22, 140.12, 141.35, 141.93,

142.19 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 409 (5.08), 525 (4.08),

554 (3.73) nm. HRMS (ES+): calcd. for C₃₉H₂₆N₄ONi 624.1460;

found 624.1474.

[5,15-Dihexyl-10-(1-hydroxybenzyl)porphyrinato]nickel(II) (22d): 5-

Porphyrin 20d (30 mg, 0.05 mmol) was dissolved in dry THF and

a solution of phenylmagnesium bromide (1  in THF, 0.5 mL,

0.5 mmol) was added. The reaction mixture was stirred at room

temp. for 1 h. The reaction was quenched with aqueous saturated

ammonium chloride (10 mL). The layers were separated, and the

aqueous layer was extracted with CH₂Cl₂. The organic layer was

washed with water several times. The solvent was evaporated, and

the product was purified by column chromatography (h = 28 cm, ø

= 3 cm, silica, CH₂Cl₂); the first fraction gave the product as purple

crystals (29.1 mg, 0.045 mmol) in 85% yield. M.p. 136 °C. R_f=

3

¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.98 (t, J = 7.31 Hz, 3

H, CH₃), 2.57 (m, 1 H, CH₂), 2.84 (m, 1 H, CH₂), 3.21 (s, 1 H,

3

OH), 6.68 (t, J = 7.31 Hz, 1 H, CH), 7.71 (m, 6 H, Ar_o,p-H), 7.99

4

(m, 4 H, Ar_m-H), 8.83 (AB/AB, ³J = 10.38, J = 4.78 Hz, 4 H, H_β),

9.09 (AB, ³J = 5.11 Hz, 2 H, H_β), 9.63 (AB, ³J = 5.11 Hz, 2 H, H_β),

9.73 (s, 1 H, H_meso) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ

= 11.45, 29.29, 35.63, 104.09, 117.64, 117.99, 126.47, 127.32,

130.00, 131.90, 132.10, 132.23, 133.23, 140.22, 140.50, 141.18,

141.84 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 409 (4.84), 525 (3.84),

556 (3.43) nm. HRMS (ES+): calcd. for C₃₅H₂₆N₄NiO 576.1460;

found 576.1481.

3

0.71 (CH₂Cl₂). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.93 (t, J

= 7.02 Hz, 6 H, CH₃), 1.37 (m, 8 H, CH₂–CH₂–CH₃+ CH₂–CH₃),

1.59 (m, 4 H, CH₂–CH₂–CH₂–CH₃), 2.26 (m, 4 H, CH₂–CH₂–

3

CH₂–CH₂–CH₃), 3.27 (br. s, 1 H, CHOH), 4.44 (t, J = 7.64 Hz, 4

H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃), 7.29 (m, 5 H, Ar_o,p-H

+

[5,15-Dihexyl-10-(1-hydroxypropyl)porphyrinato]nickel(II) (22b): (5-

Formyl-10,20-dihexylporphyrinato)nickel(II) 20d (30 mg,

0.05 mmol) was dissolved in dry THF and a solution of ethylmag-

nesium bromide (3  in Et₂O, 85 µL, 0.25 mmol) was added. The

reaction mixture was heated to reflux at 75 °C for 12 h. The reac-

tion was quenched with aqueous saturated ammonium chloride

(10 mL). The layers were separated; the aqueous layer was ex-

tracted with CH₂Cl₂. The organic layer was washed with water sev-

eral times. The solvent was evaporated, and the product was puri-

CDCl₃), 7.52 (m, 2 H, Ar_m-H), 7.79 (br. s, 1 H, CHOH), 9.07 (AB,

³J = 4.61 Hz, 2 H, H_β), 9.16 (AB, ³J = 5.19 Hz, 2 H, H_β), 9.20

(AB, ³J = 5.48 Hz, 2 H, H_β), 9.28 (AB, ³J = 4.61 Hz, 2 H, H_β),

9.51 (s, 1 H, H_meso) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ

= 13.71, 22.25, 29.64, 31.32, 33.55, 37.07, 74.36, 103.46, 115.47,

117.09, 125.89, 127.64, 129.26, 129.78, 130.39, 132.07, 140.05,

140.72, 140.88, 141.87, 146.42 ppm. UV/Vis (CH₂Cl₂): λ (log ε) =

412 (5.21), 530 (4.18), 564 (3.71) nm. HRMS (ES+): calcd. for

C₃₉H₄₂N₄ONi 640.2712; found 640.2741.

Eur. J. Org. Chem. 2007, 3833–3848

www.eurjoc.org

3845

K. Dahms, M. O. Senge, M. B. Bakar

FULL PAPER

[5,15-Dihexyl-10,20-bis(1-hydroxybenzyl)porphyrinato]nickel(II)

(22e): Diformylporphyrin 20e (50 mg, 0.08 mmol) was dissolved in

dry THF and a solution of phenylmagnesium bromide (1  in THF,

132.49, 133.18, 133.49, 139.66, 139.92, 141.43, 141.96, 142.66,

149.69 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 420 (5.31), 536 (4.31),

576 (4.12) nm. HRMS (ES+): calcd. for C₃₅H₂₂N₅Ni 570.1229;

1.6 mL, 1.6 mmol) was added. The reaction mixture was stirred at found 570.1230.

room temp. for 12 h. Subsequent workup was as described for 22d.

(5,15-Dicyanoethenyl-10,20-dihexylporphyrinato)nickel(II) (24b): To

Yield: 40.6 mg (0.05 mmol, 68%) of purple crystals. M.p. 147 °C.

a suspension of (cyanomethyl)triphenylphosphonium chloride

(340 mg, 1 mmol) in dry THF was added n-butyllithium (2.5  in

hexane, 0.4 mL), and the suspension was stirred for 5 min. Follow-

ing the addition of (5,15-diformyl-10,15-dihexylporphyrinato)-

nickel(II) 20e (30 mg, 0.05 mmol) the reaction mixture was stirred

at room temp. After 1 h, (cyanomethyl)triphenylphosphonium

chloride (340 mg, 1 mmol) and n-butyllithium (2.5  in hexane,

0.4 mL) were added, and the mixture was stirred for 12 h. Subse-

quent workup was as described for 24a. Yield: 3.3 mg (0.005 mmol,

10%) dark green crystals. M.p. 142 °C. R_f= 0.62 (CH₂Cl₂). ¹H

1

R_f= 0.22 (CH₂Cl₂). H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.89

(t, ³J = 7.53 Hz, 6 H, CH₃), 1.33 (m, 8 H, CH₂–CH₃+ CH₂–CH₂–

CH₃), 1.54 (m, 4 H, CH₂–CH₂–CH₂–CH₃), 2.19 (m, 4 H, CH₂–

CH₂–CH₂–CH₂–CH₃), 4.38 (t, ³J = 7.89 Hz, 4 H, CH₂–CH₂–CH₂–

CH₂–CH₂–CH₃), 7.28 (m, 9 H, Ar_o,p-H+ CDCl₃), 7.55 (m, 4 H,

Ar_m-H), 7.80 (br. s, 2 H), 9.14 (AB, ³J = 5.26 Hz, 4 H, H_β), 9.21

3

(AB, J = 5.26 Hz, 4 H, H_β) ppm. ¹³C NMR (100.6 MHz, CDCl₃,

20 °C): δ = 13.69, 22.25, 29.59, 31.28, 33.45, 36.97, 125.89, 126.29,

127.69, 130.07, 130.94 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 420

(4.99), 541 (4.11), 574 (3.71) nm. HRMS (ES+): calcd. for

C₄₆H₄₈N₄O₂Ni 746.3131; found 746.3107.

3

NMR (400 MHz, CDCl₃, 20 °C): δ = 5.56 (d, J = 16.94 Hz, 2 H,

3

CH), 9.17 (AB, J = 4.89 Hz, 4 H, H_β), 9.22 (AB, J = 4.89 Hz, 4

H, H_β), 9.41 (d, ³J = 16.94 Hz, 2 H, CH) ppm. ¹³C NMR

(150 MHz, CDCl₃, 20 °C): δ = 13.91, 22.45, 29.55, 29.83, 31.52,

33.71, 37.19, 67.83, 108.30, 108.75, 117.95, 120.36, 131.26, 131.39,

131.52, 139.19, 141.66, 148.83 ppm. UV/Vis (CH₂Cl₂): λ (log ε) =

440 (4.86), 571 (3.71), 625 (4.05) nm.

[5-(1-Hydroxybut-3-enyl)-10,20-diphenylporphyrinato]nickel(II)

(22f): Compound 3b (30 mg, 0.05 mmol) was dissolved in dry THF

and a solution of allylmagnesium bromide (1  in Et₂O, 0.5 mL,

0.5 mmol) was added. The reaction mixture was stirred at room

temp. for 6 h. The reaction mixture was stirred at room temp. for

12 h. Subsequent workup was as described for 22d. Yield: 26 mg

[5,15-Dihexyl-10,20-bis(4-nitrophenylethenyl)porphyrinato]nickel(II)

(24c): To a suspension of (4-nitrophenyl)triphenylphosphonium

bromide (134 mg, 0.28 mmol) in dry THF was added n-butyllith-

ium (2.5  in hexane, 0.07 mL), and the suspension was stirred for

5 min. (5,15-Diformyl-10,15-dihexylporphyrinato)nickel(II) 20e

(30 mg, 0.055 mmol) was added, and the reaction mixture was

stirred for 2 d at room temp. It was quenched with water, CH₂Cl₂

was added and the phases were separated. The organic layer was

washed with water several times. The solvent was evaporated, and

the product was purified by column chromatography (h = 28 cm, ø

= 3 cm, silica, CH₂Cl₂) to yield purple crystals (4.8 mg,

0.006 mmol, 11%). M.p. 296 °C. R_f= 0.44 (CH₂Cl₂/C₆H₁₄, 2:1).

(0.044 mmol, 80 %) of purple crystals. M.p. 96 °C. R_f

=

1

0.42(CH₂Cl₂). H NMR (400 MHz, CDCl₃, 20 °C): δ = 3.15–3.18

[m, 2 H, CH(OH)(CH₂)], 3.53 [m, 1 H, CH(OH)(CHЈ₂)], 5.04 (dd,

4

3

4

³J = 10.04, J = 1.00 Hz, 1 H, CH=CH₂), 5.19 (dd, J = 16.06, J

3

4

= 1.00 Hz, 1 H, CH=CH₂), 5.88 (AB/AB, J = 5.02, J = 4.02 Hz,

1 H, CH =CH₂), 6.71 [CH(OH)(CH₂)], 7.63 (m, 6 H, Ar_o,p-H), 7.89

3

(m, 4 H, Ar_m-H), 8.71 (AB, J = 5.02 Hz, 2 H, H_β), 8.74 (AB, J =

5.02 Hz, 2 H, H_β), 8.98 (AB, ³J = 5.02 Hz, 2 H, H_β), 9.51 (AB, ³J =

5.02 Hz, 2 H, H_β), 9.60 (s, 1 H, H_meso) ppm. ¹³C NMR (100.6 MHz,

CDCl₃, 20 °C): δ = 47.25, 74.00, 104.16, 117.14, 117.52, 117.69,

126.46, 127.32, 129.87, 131.92, 132.10, 132.32, 133.23, 134.98,

140.18, 140.29, 141.16, 141.84, 141.87 ppm. UV/Vis (CH₂Cl₂): λ

(log ε) = 408 (5.01), 524 (4.04), 556 (3.61) nm. HRMS (ES+): calcd.

for C₃₆H₂₆N₄NiO 588.1460; found 588.1479.

3

¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.91 (t, J = 7.11 Hz, 6

H, CH₃), 1.34 (m, 8 H, CH₂–CH₃+ CH₂–CH₂–CH₃), 1.58 (m, 4

H, CH₂–CH₂–CH₂–CH₃), 2.24 (m, 4 H, CH₂–CH₂–CH₂–CH₂–

CH₃), 4.41 (t, ³J = 8.01 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃),

6.74 (d, ³J = 14.85 Hz, 2 H, CH), 7.84 (d, ³J = 8.77 Hz, 4 H, Ar_H),

8.35 (d, ³J = 8.18 Hz, 4 H, Ar_H), 9.20 (AB, ³J = 4.62 Hz, 4 H, H_β),

9.25 (AB, ³J = 5.40 Hz, 4 H, H_β) ppm. ¹³C NMR (150 MHz,

CDCl₃, 20 °C): δ = 11.00, 13.68, 22.19, 24.83, 28.61, 29.26, 29.58,

31.29, 33.38, 34.22, 36.77, 111.92, 118.82, 123.94, 126.48, 129.99,

131.29, 139.58, 140.69, 140.93, 143.19, 146.51 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 465 (5.17), 646 (4.61) nm.

(5-Cyanoethenyl-10,20-diphenylporphyrinato)nickel(II) (24a): To a

suspension of (cyanomethyl)triphenylphosphonium bromide

(52 mg, 0.15 mmol) in dry THF was added n-butyllithium (2.5  in

hexane, 0.04 mL), and the suspension was stirred for 5 min fol-

lowed by the addition of (5-formyl-10,15-diphenylporphyrinato)-

nickel(II) 3b (30 mg, 0.05 mmol). The reaction mixture was stirred

at room temp. for 2 h and then heated to reflux (75 °C) for 12 h.

A suspension of (cyanomethyl)triphenylphosphonium bromide

(52 mg, 0.15 mmol) and n-butyllithium (2.5  in hexane, 0.04 mL)

in dry THF was added. The mixture was stirred for 12 h and

quenched with water. CH₂Cl₂was added and the phases were sepa-

rated. The organic layer was washed with water several times. The

solvent was evaporated, and the product was purified by column

(5,15-Dihexyl-10-vinylporphyrinato)nickel(II) (24d): To a suspen-

sion of methyltriphenylphosphonium bromide (50 mg, 0.14 mmol)

in dry THF was added n-butyllithium (2.5  in hexane, 0.03 mL),

and the suspension was stirred for 5 min. The addition of (5-for-

chromatography (h = 30 cm, ø = 3 cm, silica, CH₂Cl₂); the first myl-10,15-dihexylporphyrinato)nickel(II) 20d (30 mg, 0.05 mmol)

fraction gave the title compound as purple crystals (25.5 mg, was followed by stirring for 1 h at room temp. The reaction was

0.044 mmol, 81%). M.p. 295 °C. R_f= 0.84 (CH₂Cl₂). ¹H NMR quenched with water, CH₂Cl₂was added and the phases were sepa-

(400 MHz, CDCl₃, 20 °C): δ = 0.92 (t, ³J = 7.15 Hz, 6 H, CH₃), rated. The organic layer was washed with water several times. The

1.35 (m, 4 H, CH₂–CH₃), 1.42 (m, 4 H, CH₂–CH₂–CH₃), 1.59 (m, solvent was evaporated, and the product was purified by column

4 H, CH₂–CH₂–CH₂–CH₃), 2.22 (m, 4 H, CH₂–CH₂–CH₂–CH₂–

chromatography (h = 30 cm, ø = 3 cm, silica, CH₂Cl₂/C₆H₁₄, 1:1);

the first fraction gave the title compound as dark red crystals

(17.2 mg, 0.03 mmol, 61%). M.p. 92 °C. R_f= 0.65 (CH₂Cl₂/C₆H₁₄,

CH₃), 4.38 (t, ³J = 8.09 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃),

3

5.68 (d, J = 15.52 Hz, 1 H, CH₃), 7.74 (m, 6 H, Ar_o,p-H), 7.99 (m,

4 H, Ar_m-H), 8.81 (AB, ³J = 4.61 Hz, 2 H, H_β), 8.88 (AB, ³J = 1:2). ¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.93 (t, ³J = 7.12 Hz,

3

4.66 Hz, 2 H, H_β), 9.08 (AB, J = 4.60 Hz, 2 H, H_β), 9.26 (AB, J 6 H, CH₃), 1.38 (m, 8 H, CH₂–CH₃+ CH₂–CH₂–CH₃), 1.62 (m,

3

= 4.60 Hz, 2 H, H_β), 9.63 (d, J = 15.52 Hz, 1 H, CH), 9.74 (s, 1

4 H, CH₂–CH₂–CH₂–CH₃), 2.31 (m, 4 H, CH₂–CH₂–CH₂–CH₂–

H, H_meso) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ = 105.85,

CH₃), 4.57 (t, ³J = 8.16 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃),

3

4

3

4

107.85, 108.05, 113.64, 117.78, 119.01, 126.65, 127.61, 129.88, 5.60 (dd, J = 17.37, J = 1.63 Hz, 1 H), 6.32 (dd, J = 10.98, J =

3846

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Exploration of meso-Substituted Formylporphyrins

FULL PAPER

4

1.19 Hz, 1 H), 8.95 (dd, ³J = 17.66, J = 10.98 Hz, 1 H), 9.08 (AB,

nikov, A. B. Preobrajenski, N. N. Sergeeva, M. M. Brzhezin-

skata, M. A. Nesterov, A. A. Cafolla, M. O. Senge, A. S. Vino-

gradov, Chem. Phys. 2007, 332, 318–324; M. O. Senge, N. N.

Sergeeva, Angew. Chem. Int. Ed. 2006, 45, 7492–7495; J. L.

Sessler, D. Seidel, Angew. Chem. Int. Ed. 2003, 42, 5134–5175.

R. Lemberg, J. Parker, Aust. J. Exp. Biol. Med. Sci. 1952, 30,

165–175; H. Fischer, H. Orth in Die Chemie des Pyrrols, Bd.

II, Tl. 1, Akademischer, Leipzig, 1943, pp. 287–293.

H. H. Inhoffen, J.-H. Fuhrhop, H. Voigt, H. Brockman, Justus

Liebigs Ann. Chem. 1966, 695, 133–143; Brockman, K. M. Blie-

sene, H. H. Inhoffen, Justus Liebigs Ann. Chem. 1968, 718,

148–161.

M. Graca, H. Vicente, L. Jaquinod, K. M. Smith, Chem. Com-

mun. 1999, 18, 1771–1782; M. Graca, H. Vicente in The Por-

phyrin Handbook (Eds.: K. M. Kadish, R. Guilard, K. M.

Smith), Academic Press, San Diego, 2000, vol. 1, pp. 149–200;

L. Jaquinod, in The Porphyrin Handbook (Eds.: K. M. Kadish,

R. Guilard, K. M. Smith), Academic Press, San Diego, 2000,

vol. 1, pp. 201–237; M. O. Senge, J. Richter, J. Porphyrins

Phthalocyanines 2004, 8, 934–953.

3

4

³J = 4.71 Hz, 2 H, H_β), 9.34 (AB/AB, J = 8.69, J = 4.71 Hz, 4

H, H_β), 9.41 (AB, ³J = 5.43 Hz, 2 H, H_β), 9.51 (s, 1 H, H_meso) ppm.

¹³C NMR (100.6 MHz, CDCl₃, 20 °C): δ = 13.69, 22.24, 29.28,

29.64, 29.88, 31.35, 33.63, 36.97, 102.89, 114.01, 117.00, 125.09,

127.46, 129.14, 129.32, 131.18, 131.86, 135.55, 139.44, 140.94,

141.31 ppm. UV/Vis (CH₂Cl₂): λ (log ε) = 414 (4.81), 534 (3.84),

622 (2.04) nm.

[7]

[8]

(5,15-Dihexyl-10,20-divinylporphyrinato)nickel(II) (24e): To a sus-

pension of methyltriphenylphosphonium bromide (150 mg,

0.42 mmol) in dry THF was added n-butyllithium (2.5  in hexane,

0.1 mL), and the suspension was stirred for 5 min. (5,15-Diformyl-

10,15-dihexylporphyrinato)nickel(II) 20e (30 mg, 0.05 mmol) was

added, and the reaction mixture was stirred for 1.5 h at room temp.

Subsequent workup was as described for 24d and gave purple crys-

tals (12.2 mg, 0.02 mmol, 41%). M.p. 123 °C. R_f= 0.17 (CHCl₃).

[9]

3

¹H NMR (400 MHz, CDCl₃, 20 °C): δ = 0.92 (t, J = 7.31 Hz, 6

H, CH₃), 1.33 (m, 8 H, CH₂–CH₃+ CH₂–CH₂–CH₃), 1.58 (m, 4

H, CH₂–CH₂–CH₂–CH₃), 2.25 (m, 4 H, CH₂–CH₂–CH₂–CH₂–

CH₃), 4.45 (t, ³J = 8.16 Hz, 4 H, CH₂–CH₂–CH₂–CH₂–CH₂–CH₃),

[10]

[11]

D. P. Arnold, A. W. Johnson, M. Mahendran, J. Chem. Soc.

Perkin Trans. 1 1978, 366–370.

X. Jiang, D. J. Nurco, K. M. Smith, Chem. Commun. 1996,

1759–1760.

3

4

3

4

5.53 (dd, J = 17.58, J = 1.75 Hz, 2 H), 6.25 (dd, J = 11.10, J =

1.53 Hz, 2 H), 8.83 (dd, J = 2 H, 16.85 Hz, 10.68 Hz), 9.22 (AB,

³J = 5.06 Hz, 4 H, H_β), 9.29 (AB, ³J = 5.22 Hz, 4 H, H_β) ppm. ¹³

C

[12]

[13]

S. Runge, M. O. Senge, Tetrahedron 1999, 55, 10375–10390.

NMR (100.6 MHz, CDCl₃, 20 °C): δ = 13.72, 22.24, 29.30, 29.61,

31.34, 33.45, 36.78, 113.57, 117.27, 127.57, 128.03, 128.10, 128.29,

129.30, 129.36, 131.40, 133.22, 133.41, 135.13 ppm. UV/Vis

(CH₂Cl₂): λ (log ε) = 426 (4.94), 548 (4.19), 596 (3.88) nm.

a) H. J. Callot, Bull. Soc. Chim. Fr. 1973, 12, 3413–3416; b)

D. P. Arnold, R. Gaete-Holmes, A. W. Johnson, A. R. P. Smith,

G. A. Williams, J. Chem. Soc. Perkin Trans. 1 1978, 1660–1670;

c) M. G. H. Vicente, K. M. Smith, J. Org. Chem. 1991, 56,

4407–4418; M. O. Senge, K. R. Gerzevske, M. G. H. Vicente,

T. P. Forsyth, K. M. Smith, Angew. Chem. Int. Ed. Engl. 1993,

32, 750–753; M. O. Senge, W. W. Kalisch, K. Ruhlandt-Senge,

Chem. Commun. 1996, 2149–2150; L. Jaquinod, D. J. Nurco,

C. J. Medforth, R. K. Pandey, T. P. Forsyth, M. M. Olmstead,

K. M. Smith, Angew. Chem. Int. Ed. Engl. 1996, 35, 1013–1016;

W. W. Kalisch, M. O. Senge, K. Ruhlandt-Senge, Photochem.

Photobiol. 1998, 67, 312–323; T. E. Clement, D. J. Nurco,

K. M. Smith, Inorg. Chem. 1998, 37, 1150–1160.

a) R. B. Woodward, W. A. Ayer, J. M. Beaton, F. Bickelhaupt,

R. Bonnett, P. Buchschacher, G. L. Closs, H. Dutler, J. Han-

nah, F. P. Hauck, S. Ito, A. Langemann, E. Legoff, W. Le-

imgruber, W. Lwoski, J. Sauer, Z. Valenta, H. Volz, J. Am.

Chem. Soc. 1960, 82, 3800–3802; b) B. Evans, K. M. Smith, J.-

H. Fuhrhop, Tetrahedron Lett. 1977, 18, 443–446; c) L. C.

Gong, D. Dolphin, Can. J. Chem. 1985, 63, 401–405; d) M. O.

Senge, J. Photochem. Photobiol., B 1992, 16, 3–36; e) M. O.

Senge, T. P. Forsyth, K. Smith, Z. Kristallogr. 1996, 211, 176–

185; f) M. O. Senge, C. J. Medforth, T. P. Forsyth, D. A. Lee,

M. M. Olmstead, W. Jentzen, R. K. Pandey, J. A. Shelnutt,

K. M. Smith, Inorg. Chem. 1997, 36, 1149–1163; g) M. O.

Senge, Chem. Commun. 2006, 243–256.

CCDC-254778 (for 16b) contains the supplementary crystallo-

graphic data for this paper.^[21]These data can be obtained free of

charge from The Cambridge Crystallographic Data Centre via

www.ccdc.cam.ac.uk/data_request/cif.

Acknowledgments

This work was generously supported by a Science Foundation Ire-

land Research Professorship Award (SFI 04/RP1/B482) and by the

Universiti Teknologi Malaysia. We are indebted to Prof. O. Lev,

The Hebrew University of Jerusalem, for preliminary MS–MS

studies.

[14]

[1] N. R. Baker, E. Rosenqvist, J. Exp. Bot. 2004, 55, 1607–1621;

E. Nagababu, J. M. Rifkind, Antioxid. Redox Signaling 2004,

6, 967–978.

[2] J. P. Collman, Y.-L. Yan, J. Lei, P. H. Dinolfo, Org. Lett. 2006,

8, 923–926; G.-Y. Gao, J. D. Harden, X. P. Zhang, Org. Lett.

2005, 7, 3191–3193; J. P. Collman, M. Kaplun, C. J. Sunder-

land, R. Boulatov, J. Am. Chem. Soc. 2004, 126, 11166–11167.

[3] T. Usui, K. Sugisaki, S. Amano, W. D. Jang, N. Nishiyama, K.

Kataoka, Cornea 2005, 24, S39–S42; P. K. Selbo, A. Hogset,

L. Prasmickaite, K. Berg, Tumour Biol. 2002, 23, 103–112.

[4] B. K. Kang, N. Aratani, J. K. Lim, D. Kim, A. Osuka, K.-H.

Yoo, Mater. Sci. Eng. C 2006, 26, 1023–1027; Y. Matsuzaki, A.

Nogami, A. Tsuda, A. Osuka, K. Tanaka, J. Phys. Chem. A

2006, 110, 4888–4899; G. d. l. Torre, P. Vázquez, F. Agulló-

López, T. Torres, Chem. Rev. 2004, 104, 3723–3750; S. M.

O’Flaherty, S. V. Hold, M. J. Cook, T. Torres, Y. Chen, M.

Hanack, W. J. Blau, Adv. Mater. 2003, 15, 19–32; E. G. A. Not-

aras, M. Fazekas, J. J. Doyle, W. J. Blau, M. O. Senge, Chem.

Commun. 2007, 2166–2168.

[15]

[16]

C. Jeandon, R. Ruppert, S. Richeter, H. J. Callot, Org. Lett.

2003, 5, 1487–1489; H. J. Callot, R. Ruppert, C. Jeandon, S.

Richeter, J. Porphyrins Phthalocyanines 2004, 8, 111–119.

Y. Song, W. A. Steen, D. Pena, Y.-B. Jiang, C. J. Medforth, Q.

Huo, J. L. Pincus, Y. Qiu, D. Y. Sasaki, J. E. Miller, J. A. Shel-

nutt, Chem. Mater. 2006, 18, 2335–2346; K. Araki, E. Mizugu-

chi, H. Tanaka, T. Ogawa, J. Nanosci. Nanotechnol. 2006, 6,

708–712; H. Murakami, T. Nomura, N. Nakashima, Chem.

Phys. Lett. 2003, 378, 481–485; E. M. Harth, S. Hecht, B.

Helms, E. E. Malmstrom, J. M. J. Frechet, C. J. Hawker, J. Am.

Chem. Soc. 2002, 124, 3926–3938.

a) C.-H. Lee, J. S. Lindsey, Tetrahedron 1994, 50, 11427–11440;

b) B. J. Littler, M. A. Miller, C.-H. Hung, R. W. Wagner, D. F.

O’Shea, P. D. Boyle, J. S. Lindsey, J. Org. Chem. 1999, 64,

1391–1396; C. Bruckner, J. J. Posakony, C. K. Johnson, R. W.

Boyle, B. R. James, D. Dolphin, J. Porphyrins Phthalocyanines

1998, 2, 455–465; c) A. Wiehe, Y. M. Shaker, J. Brandt, S.

Mebs, M. O. Senge, Tetrahedron 2005, 61, 5535–5564.

[17]

[5] M. A. Awan, S. A. Tarin, Surgery 2006, 4, 231–236; S. A. Gor-

man, S. B. Brown, J. Griffiths, J. Environ. Pathol. Toxicol. On-

col. 2006, 25, 79–108; M. R. Detty, S. L. Gibson, S. J. Wagner,

J. Med. Chem. 2004, 47, 3897–3915.

[6] K. M. Kadish, R. Guilard, K. M. Smith (Eds.), The Porphyrin

Handbook, Academic Press, San Diego, 2000, 2003; S. A. Kras-

Eur. J. Org. Chem. 2007, 3833–3848

www.eurjoc.org

3847

K. Dahms, M. O. Senge, M. B. Bakar

FULL PAPER

[18] a) J. Setsune, T. Yazawa, H. Ogoshi, Z. Yoshida, J. Chem. Soc.

Perkin Trans. 1 1980, 1641–1645; b) W. W. Kalisch, M. O.

Senge, Angew. Chem. Int. Ed. 1998, 37, 1107–1109; M. O.

Senge, W. W. Kalisch, I. Bischoff, Chem. Eur. J. 2000, 6, 2721–

2738; X. Feng, I. Bischoff, M. O. Senge, J. Org. Chem. 2001,

66, 8693–8700; M. O. Senge, Acc. Chem. Res. 2005, 38, 733–

743.

[19] D. Seebach, E. J. Corey, J. Org. Chem. 1975, 40, 231–237.

[20] Y. Fumoto, H. Uno, T. Murashima, N. Ono, Heterocycles 2001,

54, 705–720.

[21] Preliminary results were reported in: M. O. Senge, S. S.

Hatscher, A. Wiehe, K. Dahms, A. Kelling, J. Am. Chem. Soc.

2004, 126, 13634–13635.

[22] a) M. O. Senge, X. Feng, J. Chem. Soc. Perkin Trans. 1 2000,

3615–3621; b) X. Feng, M. O. Senge, Tetrahedron 2000, 56,

587–590; Y. M. Shaker, M. O. Senge, Heterocycles 2005, 65,

2441–2450.

[31]

[32]

Formation of this compound is due to the presence of minor

amounts of ethanol in the solvent used.

D. M. Wallace, S. H. Leung, M. O. Senge, K. M. Smith, J. Org.

Chem. 1993, 58, 7245–7257; J. Takeda, M. Sato, Chem. Lett.

1994, 2233–2236.

K. M. Smith, Z. Martynenko, R. K. Pandey, H. D. Tabba, J.

Org. Chem. 1983, 48, 4296–4302; C.-H. Lee, F. Li, K. Iwamoto,

J. Dadok, A. A. Bothner-By, J. S. Lindsey, Tetrahedron 1995,

51, 11645–11672; B. J. Littler, Y. Ciringh, J. S. Lindsey, J. Org.

Chem. 1999, 64, 2864–2872.

J. W. Buchler in Porphyrins and Metalloporphyrins (Ed.: K. M.

Smith), Academic Press, New York, 1975, pp. 157–231.

[33]

[34]

[35]

[36]

A. W. Johnson, D. Oldfield, J. Chem. Soc. 1966, 794–798.

K. M. Smith, G. M. F. Bisset, J. Chem. Soc. Perkin Trans. 1

1981, 2625–2630.

[37]

a) H. J. Callot, Tetrahedron 1973, 29, 899–901; b) H. J. Callot,

B. Castro, C. Selve, Tetrahedron Lett. 1978, 32, 2877–2880;

G. V. Ponomarev, G. B. Maravin, Khim. Geterotsikl. Soedin.

1982, 1, 59–64; K. M. Smith, E. M. Fujinari, K. C. Langry,

D. W. Parish, H. D. Tabba, J. Am. Chem. Soc. 1983, 105, 6638–

6646.

a) R. G. E. Coumans, J. A. A. W. Elemans, P. Thordarson,

R. J. M. Nolte, A. E. Rowan, Angew. Chem. Int. Ed. 2003, 42,

650–654; b) P. C. M. van Gerven, J. A. A. W. Elemans, J. W.

Gerritsen, S. Speller, R. J. M. Nolte, A. E. Rowan, Chem. Com-

mun. 2005, 3535–3537; c) S. J. Langford, M. J. Latter, C. P.

Woodward, Org. Lett. 2006, 8, 2595–2598.

[23] Sterically hindered RLi can react at the porphyrin β positions

with the formation of chlorins. See ref.^[18b]and: B. Krattinger,

H. J. Callot, Eur. J. Org. Chem. 1999, 1657–1667.

[24] a) Y. Wan, O. D. Mitkin, L. Barnhurst, A. N. Kurchan, A. G.

Kutateladze, Org. Lett. 2000, 2, 3817–3819; O. D. Mitkin, Y.

Wan, A. N. Kurchan, A. G. Kutateladze, Synthesis 2001, 8,

1133–1142; O. D. Mitkin, A. N. Kurchan, Y. Wan, B. F. Schi-

wal, A. G. Kutateladze, Org. Lett. 2001, 3, 1841–1844; b) W. A.

McHale, A. G. Kutateladze, J. Org. Chem. 1998, 63, 9924–

9931; P. Vath, D. E. Falvey, L. A. Barnhurst, A. G. Kutatel-

adze, J. Org. Chem. 2001, 66, 2887–2890.

[38]

[25] A. I. Meyers, R. C. Strickland, J. Org. Chem. 1972, 37, 2579–

2582; H. Kunz, R. Barthels, Chem. Ber. 1982, 115, 833–845.

[26] S. S. Hatscher, Dissertation, Freie University of Berlin, 2003.

[27] M. O. Senge, I. Bischoff, N. Y. Nelson, K. M. Smith, J. Porphy-

rins Phthalocyanines 1999, 3, 99–116.

[39] a) P. Yon-Hin, T. P. Wijesekera, D. Dolphin, Tetrahedron Lett.

1989, 30, 6135–6138; b) P. Yon-Hin, T. P. Wijesekera, D. Dol-

phin, New J. Chem. 1992, 16, 537–539; c) P. A. Liddell, L. J.

Demanche, S. Li, A. N. Macpherson, R. A. Nieman, A. L.

Moore, T. A. Moore, D. Gust, Tetrahedron Lett. 1994, 35, 995–

998.

[28] a) This is probably a result of the geometry in the transition

state required for the removal of the hydrogen atoms. Similar [40] a) A. R. Morgan, G. M. Garbo, R. W. Keck, R. A. Miller, S. H.

fragmentation reactions of dithian-2-yl residues have been de-

scribed in mass spectrometric studies. See: A. Sturaro, P. Traldi,

Org. Mass Spectrom. 1986, 21, 335–341; b) An indication of the

relative (in)stability of the dithian-2-ylporphyrins was obtained

from MS–MS fragmentation studies (collision induced dissoci-

ation). An estimation of the relative gas phase stability of the

dithian-2-ylporphyin ions showed a decreasing order of sta-

bility in the series 16b Ͼ 14b Ͼ 14a Ͼ 14c Ͼ 14d. Personal

communication: O. Lev, J. Gun, The Hebrew University of Je-

rusalem.

Selman, D. Skalkos, J. Med. Chem. 1990, 33, 1258–1262; b) X.

Liu, E. Sternberg, D. Dolphin, Chem. Commun. 2004, 852–853.

[41] a) M. Morisue, S. Yamatsu, N. Haruta, Y. Kobuke, Chem. Eur.

J. 2005, 11, 5563–5574; b) T. Ishida, Y. Morisaki, Y. Chujo,

Tetrahedron Lett. 2006, 47, 5265–5268.

[42] a) C. M. A. Alonso, M. G. P. M. S. Neves, A. C. Tome,

A. M. S. Silva, J. A. S. Cavaleiro, Tetrahedron Lett. 2001, 42,

8307–8309; b) C. M. A. Alonso, M. G. P. M. S. Neves, A. C.

Tome, A. M. S. Silva, J. A. S. Cavaleiro, Eur. J. Org. Chem.

2004, 3233–3239.

[29] The increasing lability of these systems often made it imposs-

ible to obtain valid mass spectrometric data (M⁺peak) or ele-

mental analyses. Likewise, the metalloporphyrins containing

1,3,5-trithianyl residues could not be investigated by using

mass spectrometry.

[30] Prior to this work, this compound was only accessible by

Vilsmeier formylation of the very insoluble (porphyrinato)cop-

per(II): R. Schlözer, J.-H. Fuhrhopp, Angew. Chem. Int. Ed.

Engl. 1975, 14, 363–364.

[43] O. B. Locos, D. P. Arnold, Org. Biomol. Chem. 2006, 4, 902–

916.

[44] M. O. Senge, I. Bischoff, Eur. J. Org. Chem. 2001, 1735–1751.

[45] a) H. Hope, Prog. Inorg. Chem. 1994, 41, 1–19; b) G. M. Sheld-

rick, SADABS, University of Göttingen, 1997; c) G. M. Sheld-

rick, SHELXS-93, University of Göttingen, 1993; d) G. M.

Sheldrick, XL-97, University of Göttingen, 1997.

Received: April 28, 2007

Published Online: July 6, 2007

3848

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Article Doi

Exploration of meso-substituted formylporphyrins and their Grignard and Wittig reactions

DOI: 10.1002/ejoc.200700380

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