The Heck reaction for porphyrin functionalisation: Synthesis of meso-alkenyl monoporphyrins and palladium-catalysed formation of unprecedented meso-β ethene-linked diporphyrins

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The Heck reaction for porphyrin functionalisation: synthesis of meso-alkenyl

monoporphyrins and palladium-catalysed formation of unprecedented meso–b

ethene-linked diporphyrins

Oliver B. Locos and Dennis P. Arnold*

Received 1st December 2005, Accepted 22nd December 2005

First published as an Advance Article on the web 25th January 2006

DOI: 10.1039/b516989e

Palladium-catalysed coupling of the vinyl derivatives methyl acrylate, styrene and acrylonitrile with

5-bromo-10,15,20-triphenylporphyrin (MTriPPBr; M = 2H, Ni, Zn) and 5,15-dibromo-10,20-bis(3,5-

di-tert-butylphenyl)porphyrin (MDAPBr₂) produced a series of mono- and disubstituted

alkenylporphyrins, thus demonstrating the applicability of meso-haloporphyrins in Heck-type reactions.

The same technique was also applied to meso-ethenylporphyrins and simple aryl halides, with mixed

results. Only meso-vinyl nickel(II) porphyrins showed any reactivity under our conditions. A mixture of

1,1- and 1,2-disubstitution across the alkene was observed for 5-vinyl-10,15,20-triphenyl-

porphyrinatonickel(II) (meso-vinylNiTriPP), whereas 5-vinyl-10,20-bis(3,5-di-t-butylphenyl)-

porphyrinatonickel(II) (meso-vinylNiDAP) produced a mixture of meso-1,1-, meso-1,2- and,

surprisingly, b-1,2-disubstituted Heck products. Coupling meso-vinylNiDAP with MTriPPBr under

similar Heck conditions led unexpectedly to trans b-meso-NiDAP-ethene-MTriPP dyads, affording the

ﬁrst members of a new class of alkenyl-linked diporphyrins. A mechanism for the unusual meso to b

rearrangement is discussed. The electronic absorption spectra of the dyads have a red-shifted shoulder

on the Soret (B) band, which is evidence of a moderate degree of electronic interaction between the

porphyrins via the ethenyl bridge.

(or alkyl)- and 5,10,15-triaryl (or alkyl)porphyrins, the meso-

bromo derivatives are the ideal starting materials, as they can be

Introduction

formed in high yields and purities.²Alkenes that usually perform

well in this type of coupling, namely a,b-unsaturated esters, nitriles,

etc., have the potential for further functional group intercon-

version, conjugation to biomolecules, or external coordination

to metal ions or other metalloporphyrins. In addition, vinylpor-

phyrins are possible Heck-type alkenes themselves, and they have

been used to a very limited extent in this manner.^16,17Moreover, by

combining a vinylporphyrin with a bromoporphyrin, a novel entry

into ethene-bridged bis- or oligoporphyrins may be possible. The

unencumbered edges of the 5,15-diarylporphyrins would appear

to offer the best chance of strong ground state interporphyrin

coupling when linked via ethenyl bridges, in contrast to the steri-

cally crowded octaalkylporphyrin building blocks.¹⁸The trans- and

cis-meso,meso-bis(octaalkylporphyrinyl)ethenes have been studied

rather extensively,¹⁹while the corresponding meso,meso-bis(5,15-

diarylporphyrinyl)ethenes surprisingly are almost unknown.³Very

recently, Anderson and co-workers have reported the crystal struc-

ture, electrochemistry and electronic spectral properties of the diz-

inc complex of a meso,meso-bis(5,10,15-triarylporphyrinyl)ethene,

prepared by the CsF–CuI variation of the Stille coupling.²⁰

Odobel’s group reported bis(5,10,15-triarylporphyrin)s linked by

the octatetraenenyl unit, prepared by a combination of Stille and

Wittig chemistry.⁵

The construction of novel porphyrins by palladium-catalysed

couplings to the periphery of the macrocycle is a topic of

considerable interest in the recent literature.¹Most of the popular

types of C–C couplings have been reported, such as aryl, vinyl

and alkynyl organometallics, boronates and boronic acids, and

terminal alkynes. However, apart from the use of the vinyl

organometallics,^2–5the coupling of alkenes directly to the por-

phyrin nucleus by Pd-catalysed methodologies has been rather

restricted in scope. Smith and co-workers reported the ﬁrst such

reactions, using b-mercurioporphyrins and alkenes, and in one

case, the b-vinylporphyrin plus phenylmercuric chloride.^6,7Others

have used b-bromoporphyrins of the natural substitution pattern

in Heck couplings, including for the synthesis of dyads and triads

linked by b-attached ethenyl–phenyl–ethenyl bridges,⁸and Odobel

and co-workers have prepared dyads linked by meso-attached

ethenyl–(thienyl)_n–ethenyl bridges using Heck-type coupling.⁹

Alkenyl-substituted porphyrins have been prepared by other

means as well, for example, by vinylogous Vilsmeier substitution,¹⁰

Wittig alkenation of formylporphyrins,^11–13or dehydration of

carbinols.¹⁴Burrell and Ofﬁcer have linked tetraarylporphyrins

through b-carbons via a variety of alkene-containing bridges

using the Wittig reaction.¹⁵These reactions have mostly involved

octaalkyl- or 5,10,15,20-tetraarylporphyrins as substrates. How-

ever, for the new generation of porphyrin substrates, the 5,15-diaryl

We have now investigated the direct coupling of some typical

Heck-type alkenes (methyl acrylate, styrene and acrylonitrile)

with meso-bromoporphyrins. Palladium-catalysed couplings on

porphyrins often behave differently depending on whether, and

with which metal ion, the porphyrin is coordinated. Therefore,

Synthesis and Molecular Recognition Program, School of Physical and

Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434,

Brisbane 40001, Australia. E-mail: d.arnold@qut.edu.au; Fax: 61 7 3864

1804; Tel: 61 7 3864 2482

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each reaction was studied for three substrates: the free base

porphyrin, the Ni(II) complex, and the Zn(II) complex. Both

mono- and dibromo substrates were used as starting materials.

Then we attempted to use the meso-vinylporphyrin as the alkene

partner, in pursuit of the goals mentioned above. Here we report

the successful use of the Heck reaction for preparing a range

of mono- and bis(alkenyl) monoporphyrins, and the lack of

success in applying the same chemistry to the formation of

meso,meso-bis(arylporphyrinyl)ethenes. However, as is often the

case with porphyrin chemistry, we discovered a very intriguing

rearrangement reaction, and this serendipitously afforded en-

try into a new type of porphyrin dyad, namely trans-meso,b-

bis(porphyrinyl)ethenes. In subsequent papers, we will report our

success in applying the Suzuki coupling to obtain the original tar-

get meso,meso-bis(porphyrinyl)ethenes, together with molecular

modelling and theoretical calculations of electronic spectra.²¹

Fig. 1 Structures of the parent porphyrin nuclei 5,10,15-triphenylpor-

phyrin (H₂TriPP) and 5,15-bis(di-t-butylphenyl)porphyrin (H₂DAPP).

Known bromination reactions with NBS produced the bro-

moporphyrins H₂2 and H₂6 in high yield (Scheme 1).²The

bromination of H₂4 to afford high yields of monobromo H₂5 is

made tedious by the lack of selectivity in the bromination and by

the difﬁculty of chromatographic separation of H₂4, H₂5 and H₂6

on a large scale. We published a way around this problem using

organopalladium porphyrins.²²In the present work, we avoided

the use of H₂5 by making the vinyl starting material by the

alternative route of Vilsmeier formylation and Wittig alkenation

(see below). The nickel(II) and zinc(II) ions were inserted into the

bromo starting materials by conventional reactions to yield Ni2,

Zn2, Ni6 and Zn6, thus allowing us to prepare the trio of coupling

products for each alkene.

Results and discussion

In this work, we used two porphyrins as scaffolds, 5,10,15-

triphenylporphyrin (H₂TriPP, H₂1) and 5,15-bis(3,5-di-tert-

butylphenyl)porphyrin (H₂DAP, H₂4) (Fig. 1). The former, which

we have used for selective mono-couplings, has advantages over

the commonly used diphenylporphyrin. Its derivatives are much

more soluble in common solvents and it has only one free meso-

carbon. Bromination and other reactions that functionalise the

meso-positions of porphyrins therefore give high yields of only

one product, and the third phenyl group effectively blocks any

adventitious processes during the coupling reactions. We employed

the latter starting porphyrin for double couplings and also as a

second porphyrin to demonstrate the use of Pd-catalysed coupling

for the selective preparation of heteronuclear dyads.

The Pd-catalysed coupling of large excesses of methyl acrylate,

styrene and acrylonitrile with monobromoporphyrins H₂2, Ni2

and Zn2 proceeded successfully (Scheme 2). The palladium

Scheme 1 Reagents and conditions: (i) H₂1 or H₂4, NBS, CHCl₃, 0 ^◦C (H₂2: 98%; H₂6: 95%); (ii) H₂1, H₂2, H₂4, H₂6 or H₂8, Ni(acac)₂, toluene, reﬂux

(Ni1: 97%; Ni2: 98%; Ni4: 98%; Ni6: 99%; Ni8: 99%); H₂2, H₂6 or H₂8, Zn(OAc)₂, CHCl₃, MeOH, reﬂux (Zn2: 90%; Zn6: 92%; Zn8: 91%); (iii) Ni1 or

Ni4, DMF, POCl₃, 1,2-DCE, 50 ^◦C (Ni3: 71%; Ni7: 73%); (iv) H₂2, CH₂CHSnBu₃, Pd₂(dba)₃, AsPh₃, THF, 50 ^◦C (H₂8: 88%); (v) Ni3 or Ni7, CH₂PPh₃,

THF, rt (Ni8: 65%; Ni13: 65%).

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Scheme 2 Reagents and conditions: (i) 1, methyl acrylate or styrene (50 eq.), Pd(OAc)₂, ligand, K₂CO₃, DMF, toluene, 105 ^◦C (75–87%); (ii) 1, acrylonitrile

(50 eq.), Pd(OAc)₂, ligand, K₂CO₃, DMF, toluene, 105 ^◦C (11, 12: 78–85%); (iii) 6, methyl acrylate or styrene (50 eq.), Pd(OAc)₂, ligand, K₂CO₃, DMF,

toluene, 105 ^◦C (14 or 15: ca 5%; 18 or 19: ca. 70%); (iv) 6, acrylonitrile (50 eq.), Pd(OAc)₂, ligand, K₂CO₃, DMF, toluene, 105 ^◦C (Ni20, Ni21, Ni22:

75%; Zn20, Zn21, Zn22: 64%).

catalysts were prepared in situ by using Pd(OAc)₂and a phosphine

ligand. The conditions for these reactions were those optimised

for the preparation of the porphyrin dyads to be described

below, although extensive optimisation was not carried out

separately for these alkene + bromoporphyrin reactions, as the

yields in almost all cases were satisfactory. The main reaction

competing with the Heck coupling was debromination of the

starting material through adventitious protolytic cleavage and,

in the case of the free-base porphyrins, metallation of the central

core with palladium sometimes occurred to a small extent. Zinc

porphyrins suffered from a small amount of demetallation and

transmetallation (∼5%). Initially these coupling reactions were

carried out in dry, deoxygenated DMF, however, the solubility

of the dibromoporphyrins proved to be extremely limited, even at

high temperatures. The solvent was subsequently changed to a 50 :

50 mixture of DMF and toluene, which allowed the reactions to

be carried out in conveniently small volumes of solvent, without

appreciably affecting the yield of the desired product.

In all cases with methyl acrylate and styrene, the trans-

alkenylporphyrins were isolated, but for acrylonitrile, the cis

isomer also formed. This is presumably due to the small steric

demand of the cyano substituent in comparison to the ester or

phenyl group of methyl acrylate and styrene. Moreover, the ratio

of the two isomers is somewhat dependent on the nature of the

coordinated metal ion. The ratio cis : trans decreased in the order

H₂> Ni > Zn, within the triphenylporphyrin series.

bis(alkenyl) products (Scheme 2). All were successful, except the

reaction of H₂6 with acrylonitrile, which led to a low yield of the

completely debrominated H₂4, and the formation of intractable

material that was not eluted from the column even with polar

solvents. Yields for the other reactions were consistently 60–70%.

Small amounts of the mono(alkenyl) debrominated compounds

14–17 were also apparent, and were readily separated from the

bis(alkenes) and identiﬁed by NMR spectroscopy. Once again,

acrylonitrile also afforded the cis products, leading to inseparable

mixtures of 20, 21, and 22 for the nickel analogues and 20 and

21 for the zinc analogues. In all these cases, the products were

1

characterised by their H NMR, accurate mass, and electronic

absorption spectra, and in most cases by CHN analysis. The

alkenyl substituent was represented by a pair of doublets with

coupling constants near 16 Hz for trans isomers and 12 Hz for cis

isomers. There were no unexpected features amongst these spectra.

Having shown initially that the Heck reaction works well for the

above processes, we turned to the original aim of seeing if the meso-

vinylporphyrin could be used as a “Heck alkene”. Two alkenyl

porphyrins were used, vinyl-NiTriPP (Ni8) and vinyl-NiDAP

(Ni13) (Scheme 3). meso-Vinyl-substituted porphyrins have previ-

ously been prepared by three methods, dehydration of the methyl

carbinol,¹⁴Wittig methylenation of the meso-formylporphyrin,^11,12

and more recently, by the Pd-catalysed Stille coupling of vinyltri(n-

butyl)stannane with meso-haloporphyrins.^2,4In this work, we tried

the last two methods. As the Vilsmeier formylation is unsuitable

for free bases and zinc complexes, H₂8 was prepared using the

Stille reaction and zinc was inserted to form Zn8, both in high

The dibromo DAP substrates H₂6, Ni6 and Zn6 were subjected

to the coupling with excess alkenes to form the corresponding

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Scheme 3 Reagents and conditions: (i) iodobenzene, Pd(OAc)₂, triphenylphosphine, K₂CO₃, DMF, toluene, 105 ^◦C (Ni10: 54%; 23: 20%); (ii) iodobenzene,

Pd(OAc)₂, triphenylphosphine, K₂CO₃, DMF, toluene, 105 ^◦C (Ni15, 24, 25 mixture: 68%); (iii) 9-bromoanthracene, Pd(OAc)₂, 2-P(t-Bu)₂biphenyl, K₂CO₃,

DMF, toluene, 105 ^◦C (26 contaminated with 27 and other impurities, ca. 10%).

yield. The nickel analogue Ni8 was obtained by both methods, i.e.,

insertion of Ni(II) into H₂8 and Wittig reaction with the Vilsmeier

product Ni3. The former route gave a higher overall yield. The

DAP analogue Ni13 was prepared exclusively by the latter route

via Ni7 (Scheme 1).

The coupling of Ni8 with a large excess of iodobenzene under

catalytic conditions similar to those described above, led to two

major products, isolable after extensive chromatography. The

product eluted ﬁrst was the 1,1-disubstituted ethene 23 and the sec-

ond was the expected 1,2-disubstituted ethene Ni10. Although the

porphyrin macrocycle is a very bulky substituent, 1,1-substitution

in the Heck reaction is by no means unprecedented, and is well

known for alkenes substituted with electron-donating groups and

in reactions involving 1,2-disubstituted alkenes.²³A third minor

product also resulted from the reaction, and was identiﬁed as

formyl-NiTriPP Ni3.

is the Wacker process, which in this case would lead to the

porphyrinylacetaldehyde. No such “normal” oxidation product

was detected.

Changing the phosphine ligand to the more bulky ligand, 2-(di-

t-butylphosphino)biphenyl, apparently resulted in the palladium

intermediate being too bulky to allow for 1,1-substitution, and

only the meso- and b-2-styrylporphyrins were produced (from

Ni13). Replacing iodobenzene with bromobenzene produced the

same Heck-coupled products for both vinylporphyrins, but more

sluggishly and with more unidentiﬁed side products. We also

attempted the coupling of Ni13 with 9-bromoanthracene as a

model for the shape of the side of a meso-haloporphyrin. This

reaction yielded both meso- and b-substituted anthracenylethenyl-

porphyrins 26 and 27, although we have been unable to purify these

so far. Interestingly, the ratio of meso- to b-alkenyl porphyrins

(by NMR) is greater for the coupling of bromoanthracene than

for iodobenzene. To investigate the rearrangement further, we

tried to couple 9-vinylanthracene with a bromoporphyrin, to see

if migration occurred from the 9- to the 1-anthryl position, by

analogy with the meso- and b-positions of a porphyrin. However,

no Heck coupling was observed at all in any conditions tried.

Perhaps these two results indicate that the anthracene “model” is

a poor one for these processes.

Heck coupling of vinyl-NiDAP Ni13 with excess iodobenzene

and PPh₃as the ligand produced a far more curious result

1

(Scheme 3). Three alkenyl products were identiﬁed by H NMR

studies, the expected 1,2-meso-styrylporphyrin Ni15, the 1,1-

meso-styrylporphyrin 24 and a 1,2-b-styrylporphyrin. Formyl-

NiDAP Ni7 was also a minor side-product. Discussion of the

possible mechanisms of this apparent meso to b rearrangement,

and the NMR proof of the structure of the b-styrylporphyrin

will be deferred until the porphyrin dyad formation has been

presented (see below). The formation of the aldehydes Ni3 and

Ni7 in these reactions is also unexpected, as the most common

oxidation for alkenes in the presence of a palladium catalyst

Having proved that, at least under some conditions, meso-

vinylporphyrins can act as the alkene partner in Heck couplings,

we tried the target reactions, i.e., the coupling of Ni13 with bromo-

porphyrins to form the meso,meso-ethenyl dyads 28 (Scheme 4).

Of course, in using these expensive starting materials, it was no

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Scheme 4 Reagents and conditions: (i) Pd(OAc)₂, ligand, K₂CO₃, DMF, toluene, 105 ^◦C (29: 23%; 30: 33%; 31: 15%).

longer feasible to use one partner or the other in large excess,

as we had done so far for simpler substrates like styrene and

iodobenzene. Not unexpectedly, the reaction was rather sluggish,

and debromination of the starting material was a problem. In

fact, the porphyrin Ni1 was isolated as the major product as a

consequence of this. However, the remarkable positive result is

that the only dinuclear porphyrin isolated was not 28, but rather

the meso,b-ethenyl-linked dyad 30. Not surprisingly, in view of the

severe steric problems, there was no 1,1-coupled product.

Our ﬁrst experiments were conducted with triphenylphosphine

as the ligand, and in view of the low yields of dyad in our

initial experiments, some optimization was attempted, examining

catalyst concentration, temperature, phosphine ligand and base,

using this coupling of Ni13 with Ni2 as a prototype. Although

these experiments were not comprehensive, due to the expense

of the two coupling partners, one signiﬁcant result was that

the bidentate chelating diphosphines dppe, dppp and dppf were

almost completely unsuccessful in this reaction, and the hin-

dered monodentate ligand 2-(di-t-butylphosphino)biphenyl gave

the highest yield. Higher temperatures (>120 ^◦C) favoured the

debromination strongly, while potassium and caesium carbonates

gave better yields than potassium phosphate. A catalyst loading

of 20% was used.

These conditions were then applied to couplings of H₂2 and Zn2,

using Ni13 as the alkene, and the yields of 29, 30, and 31, although

only modest (33, 23 and 15%, respectively), were sufﬁcient for

characterisation and comparison. In each case, the only dyads

detected were those linked to a 2-b-carbon on the NiDAP unit, and

the 5-meso-carbon on the other partner. The rearrangement thus

provided a new trio of trans-ethenyl-linked dyads, representing a

new class of heterobis(porphyrin)s to add to the known b,b and

meso,meso types.

The dinuclear structures were apparent from the mass spectra.

Accurate mass measurements were possible using electrospray

ionization for free base 29, which exhibited a clear [M + H]⁺

ion cluster. Laser desorption-TOF spectra gave molecular ion

clusters at the expected m/z values for 30 and 31. The position

of substitution of the bridge in the dyads was established by their

1D and 2D (COSY and NOESY) ¹H NMR spectra. The obvious

indicator of the 2-ethenyl-5,15-diarylporphyrin fragment in 29, 30,

and 31 is the presence of 17 porphyrinic protons, distributed as

three singlets, representing the two meso-Hs and the unique 3-b-H

on the NiDAP side, six doublets for the inequivalent protons on

the other three pyrrole rings of NiDAP, and a further four sets of

doublets for the two pairs of equivalent rings on the MTriPP side.

The two doublets for the trans-ethenyl protons (J ca. 15.5 Hz)

were observed in all cases. There is a clear distinction between

the chemical shifts of the b-attached and meso-attached alkene

CH units; the CH protons next to the NiDAP appear at 8.92, 8.36

and 8.88 ppm for 29, 30, and 31, respectively. Conversely, those

adjacent to the meso-attached TriPP resonate at 10.30, 9.89 and

10.44 ppm for 29, 30, and 31. These shifts are congruent with

those for the CH protons adjacent to MTriPP in, for example,

the meso-styryl derivatives H₂10, Ni10 and Zn10 (9.68, 9.31, 9.78

ppm). The only other examples of rearranged, b-alkenyl units

for NiDAP are the styryl (25) and anthracenyl (27) derivatives.

The alkenyl protons were not found for 27, but in 25, this signal

appeared at 8.63 ppm.

The 2D NMR experiments (DQF COSY and gradient NOESY)

were performed on the dyad 29 to assign the protons deﬁnitively

(Fig. 2, 3). For the H₂TriPP fragment, the 2D spectra showed

normal scalar couplings and NOEs for a triphenylporphyrin.

The major points of interest were the resolution of the ortho-

Hs on the inequivalent phenyl rings, 2e and 2f, highlighting the

strong electronic effects of the alkenylporphyrin substituent at the

meso position, and the observation of NOEs between both alkene

protons and the b-Hs 2a.

For the NiDAP fragment, the starting point was the singlet

arising from b-H 1b. By comparison with the monoporphyrins,

this was logically assigned initially as the singlet with the lowest

chemical shift (9.65 ppm), and an NOE resulting from an ortho-

proton, 1k, conﬁrmed this belief. It was hoped that an NOE would

be seen between meso-H 1a and an alkenyl proton, which would

readily distinguish between the two sides of the ring. This was

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The electronic absorption spectra of the novel dyads show

evidence of interaction between the porphyrin transition dipoles

=

across the potentially conjugated-CH CH-bridge. In Fig. 4, we

show the spectrum of the Ni₂complex 30, together with that of

an analogous alkenyl-monoporphyrin, namely styryl-substituted

Ni10, and the parent Ni1, for comparison. The intense Soret (B)

band is almost split into two components, resulting in a strong

shoulder on the red side. The lowest-energy Q band is signiﬁcantly

red-shifted with respect to the monoporphyrins. These features

are consistent with a modest degree of interporphyrin ground state

interactionviaapartiallyconjugatedbridge. Twofeatures arelikely

to diminish this coupling, compared with dyads (such as those

joined by meso,meso-alkyne bridges) with strong interporphyrin

coupling: (i) the expected twisting of the alkene with respect to

the porphyrin plane(s), which reduces p–p overlap via the bridge

orbitals; (ii) the linkage through the b-carbon on one side. The

former is due to steric interference between the alkene CHs and the

peripheral porphyrin Hs, and is expected, from crystallographic

studies on related mono- and di-porphyrins, to be less pronounced

on the b-linked side.¹⁵The latter is a consequence of the smaller

Fig. 2 Labelling of the proton positions in the meso,b-dyad 29 (see text

and Fig. 3).

not the case; however, one of the meso-protons experienced only

one NOE due to a neighbouring b-H, whereas the other meso-

proton exhibited two NOEs arising from two neighbouring b-Hs.

This allowed these two meso-protons to be distinguished as 1a

and 1e, respectively. The NOEs between 1k and 1c and between

1j and 1g, together with the assistance of the COSY spectrum,

conﬁrmed the assignments of 1c, 1d, 1e, 1f and 1g. Although no

NOE was observed between 1j and 1h, the assignment of 1a led

to the conﬁrmation of the chemical shift of 1i from the NOESY

spectrum and subsequently 1h from its scalar coupling with 1i

observed in the COSY. The chemical shifts of protons 1l and 1m

were identiﬁed by COSY cross-peaks.

We note that while the b-Hs 2a gave observable NOEs from the

alkenyl Hs, 3a and 3b, we could not resolve any dipolar couplings

from the alkenyl protons to either the meso-H 1a or b-H 1b. It

is understandable with the resolution of a 2D experiment that

with the overlapping chemical shifts, no coupling can be observed

between 3a and 1a. However, the lack of coupling of 1a and 1b

with 3b remains unexplained at present. Thus the conformation

of 29 drawn in Fig. 2 is for convenience only, and is not meant to

imply that it is the preferred one.

Fig. 4 UV–Visible absorption spectra of parent porphyrin Ni1 (solid

line), meso-styryl Ni10 (dashed) and dinickel meso,b-dyad 30 (dotted) in

CHCl₃.

Fig. 3 Downﬁeld region of the ¹H NMR spectrum of meso,b-dyad 29 in CDCl₃; the protons are labelled according to Fig. 2.

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Scheme 5 Possible mechanism for the meso to b migration during the Pd-catalysed coupling of meso-vinylporphyrins with meso-bromoporphyrins.

2

orbital coefﬁcients at the b-carbons than at the meso-carbons in

the occupied frontier orbitals, and this feature has been described

in some detail, especially for alkyne-linked dyads.²⁴The meso,meso

ethene-linked triarylporphyrin dizinc dyad recently described by

Anderson and co-workers displays a split Soret band with maxima

at 422 and 480 nm, which they compared with the corresponding

meso,meso ethyne-linked dyad, whose Soret components have

maxima at 408 and 483 nm.²⁰Detailed discussions of equilibrium

geometries, electronic spectra and theoretical comparisons with

meso,meso ethenyl-linked dyads will be the topics of a subsequent

paper.²¹

followed by g -coordination of the alkene partner (Scheme 5).

After insertion of the alkene into the Pd–C bond and then b-H

elimination, the coupling product is extruded, and the Pd hydride

collapses again to a catalytic Pd(0) species.²⁵From our results, it

seems that it is unfavourable for the bis(porphyrinyl)palladium(II)

intermediate (Scheme 5, 32) to reach a conformation that al-

lows b-H elimination, namely with the palladium syn to that

hydrogen. While this conformation can be achieved to some

extent in the coupling of smaller haloarenes (e.g. iodobenzene)

with vinylporphyrins, the hindrance due to the presence of

two porphyrins makes the elimination of an e-H from the b-

position on the porphyrin a viable (albeit low-yielding) alternative.

Another signiﬁcant point is that the chelating diphosphines

gave almost no coupling products, and moreover the bulkier

phosphine gave somewhat better yields than triphenylphosphine.

This suggests that the key steps occur on a species with either trans-

directed phosphine ligands, or more likely, on Pd(II) [or Pd(IV)]

intermediates that have only one coordinated phosphine ligand.

Cyclopalladation onto the 2-carbon is an attractive proposition,

Mechanistic considerations

The fact that only the meso,b-dyads were isolated from the

coupling of a meso-vinylporphyrin with a meso-bromoporphyrin

is noteworthy, and so some consideration of the mechanism is

warranted. The standard version of the Heck coupling cycle

involves oxidative addition of the haloarene to a Pd(0)L_nfragment,

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although this requires a Pd(IV) intermediate, e.g., 33 (Scheme 5). A

possible pathway for a migratory reductive elimination is shown, to

give a Pd(II) intermediate that can collapse as expected to eliminate

the meso,b-dyad.

Experimental

General

All solvents were Analytical Reagent grade unless otherwise

stated. The following solvents and reagents were distilled prior

to use (under Ar): pyrrole; phosphorus oxychloride; THF from

sodium/benzophenone; dichloromethane and 1,2-dichloroethane

from calcium hydride; and triethylamine and pyridine from potas-

sium hydroxide. Phosphine ligands were obtained from Sigma-

Aldrich or Strem, and metal salts were obtained from Sigma-

Aldrich. TLC was performed on Merck Silica Gel 60 F254 TLC

plates. Preparative column chromatography was performed on

silica gel (40–63lm), which was purchased from Qindao Haiyang

Chemical Co. Ltd., China.

¹H, DQF COSY and NOESY NMR experiments were con-

ducted on a Bruker Avance 400 spectrometer operating at

400.155 MHz. All samples were prepared in CDCl₃and chemical

shifts were referenced to CHCl₃at 7.26 ppm. Coupling constants

are given in Hz. Solutions of zinc porphyrins were prepared with

the addition of 10 lL d₅-pyridine (ca. 1%). Microanalyses were

performed by the Microanalytical Service, School of Molecular

and Microbial Sciences, The University of Queensland. UV–

Visible spectra were recorded on a Varian Cary 3 or Varian Cary

50 UV–visible spectrometer in CHCl₃.

Accurate Electrospray Ionisation (ESI) and Laser Desorption

Ionisation (LDI) mass spectra were recorded at the School of

Chemistry, Monash University, Melbourne. ESI measurements

were performed using an Agilent 1100 Series LC attached to an

Agilent G1969A LC-TOF system with reference mass correction

using NaI clusters. An eluent of 50 : 50 CH₂Cl₂–MeOH with 0.1%

formic acid was employed using a ﬂow rate of 0.3 mL min⁻¹.

For the ESI probe, solvent aspiration was achieved by nitrogen

gas ﬂowing at 8 L min⁻¹. The source temperature was set to

350 ^◦C and the capillary voltage to 4.0 kV. LDI MS analyses

were performed with an Applied Biosystems Voyager-DE STR

BioSpectrometry Workstation. The instrument was operated in

positive polarity in reﬂectron mode. Data from 500 laser shots

employing a 337 nm nitrogen laser were collected, the signal was

averaged, and processed with the instrument manufacturer’s Data

Explorer software.

It is desirable to obtain evidence of the fate of the various

hydrogens that participate in the reaction, and the origin of the new

meso-H in the rearranged dyad. The dideuterio-vinylporphyrin 34

was synthesised from deuterated ylide and Ni8, and coupled with

Ni2. The product was conﬁrmed to be monodeuterio 35, by the

absence of the 9.89 ppm doublet in its NMR spectrum, together

with the observation of a broad singlet, rather than a doublet, at

8.36 ppm. However, the meso-H at 10.03 ppm was unchanged, so

it does not arise speciﬁcally by migration from the terminal alkene

carbon, but may come from the b-porphyrin carbon (via the Pd

in our proposal) or from the DMF or toluene or adventitiously

from trace impurities in the solvents. The coupling of undeuterated

substrates in d₇-DMF afforded completely non-deuterated dyad.

Without more detailed labelling experiments, we cannot make any

more statements on mechanistic possibilities at this stage.

The bromoporphyrin Ni2 and vinylporphyrin Ni13 were sepa-

rately subjected to Heck conditions without the complementary

partner for 4 days at 105 ^◦C. The bromoporphyrin was 30%

debrominated over this time, while 5% of the vinylporphyrin

had been converted to formylporphyrin. The latter reaction was

repeated and left for 7 days and the amount of formylporphyrin

increased to 8%. This incidentally rules out formation of the

formylporphyrin via the bromoporphyrin, as well as indicating

that apparently both partners have to be engaged on the palladium

for the migration to occur.

Conclusions

meso-Bromo- and meso-ethenylporphyrins have been investigated

as potential Heck synthons. While the bromoporphyrins proved

efﬁcient in Heck coupling with typical electron-deﬁcient alkenes,

namely methyl acrylate, acrylonitrile and styrene, to produce

mononuclear alkenylporphyrins, ethenylporphyrins gave mixtures

of 1,1-, 1,2-, and surprisingly, b-1,2-disubstituted alkenylpor-

phyrins. In attempting to form meso,meso-ethenyl(bis)porphyrins

through the same procedures, only meso,b-linked dyads were

isolated. This has fortuitously enabled the study of the spectra

of this new type of dyad in comparison with other conjugated or

partially conjugated carbon-bridged dyads.

We offer a possible mechanism for the rearrangement, however,

deuteration studies have so far not provided evidence for or against

this mechanism. However, rearrangements accompanying metal-

catalysed coupling may open new pathways for novel synthetic

reactions in the meso,b-region of porphyrins. In our own work

with b-mercurioporphyrins, we have seen other examples of sub-

stituents “walking” from one b-carbon to a neighbouring position

during Pd-catalysed reactions.²⁶We predict the development of

a range of similar reactions that involve metal-induced C–H

activations on porphyrins, and note the recent work of Boyle

and Fox²⁷, and Cammidge et al.,²⁸and the pioneering results of

Smith et al.⁶on intramolecular cyclisations on porphyrins induced

by palladium catalysts. Moreover, Osuka’s group has recently re-

ported Ir-induced b-boronation of porphyrins, a reaction that also

involves transition metal-induced C–H activation on porphyrins.²⁹

Starting materials

The following parent porphyrins, meso-substituted porphyrins,

and their complexes with Ni(II) and Zn(II), were prepared ac-

cording to published procedures for these or similar compounds:

H₂1,³⁰Ni1,³⁰H₂2,³¹Ni2,³¹Zn2,³²H₂4,³³H₂6,³⁴Zn6³³and Zn8.^4,35

5-Formyl-10,15,20-triphenylporphyrinatonickel(II) (Ni3). The

method was adapted from a procedure reported for similar

porphyrins by Johnson and Oldﬁeld.³⁶A dry 100 cm³two neck

ﬂask was ﬁtted with a dropping funnel and septum. The system

was purged with argon, and dry DMF (4 cm³, 50 mmol) was

added and the mixture was chilled to 0 ^◦C. Freshly distilled POCl₃

(4.6 cm³, 49 mmol) was added dropwise via a syringe, with stirring.

The Vilsmeier reagent was allowed to warm to room temperature

and stirred for 30 min. The pale yellow reagent was heated to

◦

50 C before a solution of Ni1 (380 mg, 0.64 mmol) in dry 1,2-

dichloroethane (75 cm³) was added dropwise over a period of

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45 min. The progress of the reaction was monitored by TLC

using CHCl₃–n-hexane (50 : 50) as the eluent. After addition

of the porphyrin, the reaction mixture was allowed to stir for a

further 2 h by which time Ni1 was no longer present. The heat

source was removed and the mixture was transferred to a 1 L ﬂask

containing saturated NaOAc solution (380 cm³) and allowed to stir

overnight. The organic layer was separated, washed with deionised

water (150 cm³× 2) and dried with Na₂SO₄. The solvent was

evaporated and the dark purple residue was subjected to column

chromatography using CHCl₃–n-hexane (75 : 25) as the eluent.

Fractions containing Ni3 were collected and recrystallised from

CHCl₃–MeOH to yield purple crystals (282 mg, 71%). d_H12.04

(1 H, s, aldehyde), 9.80 (2 H, d, ³J 5.1, b-H), 8.85 (2 H, d, ³J 5.1,

5-Ethenyl-10,15,20-triphenylporphyrin (H₂8). The method was

adapted from a procedure reported by Liebeskind et al.⁴Porphyrin

H₂2 (200 mg, 0.33 mmol), Pd₂(dba)₃(15 mg, 0.016 mmol)

and AsPh₃(39 mg, 0.13 mmol) were added to a Schlenk ﬂask

which was evacuated and subsequently charged with argon. Dry,

deoxygenated THF (20 cm³) and tri-n-butyl(vinyl)tin (130 lL,

0.44 mmol) were added and the ﬂask was sealed and heated to

50 ^◦C. The progress of the reaction was monitored by TLC using

CH₂Cl₂–n-hexane (50 : 50) as the eluent. After 2.5 h the reaction

was complete and the solvent was removed under vacuum. The

product was puriﬁed by passage through a plug of silica gel using

CH₂Cl₂–n-hexane as the eluent (40 : 60) and recrystallised using

CH₂Cl₂–MeOH to give purple crystals (163 mg, 88%). d_H9.50

3

b-H), 8.64 (2 H, d, J 4.9, b-H), 8.57 (2 H, d, J 4.9, b-H), 7.95

(4 H, m, o-Ph–H), 7.68 (2 H, t, m,p-Ph–H); UV–vis: k_max(log e)

424 (5.15), 553 (3.84), 597 (4.00) nm. MS (LDI⁺) m/z = 622.08.

Calc. M⁺for C₃₉H₂₄N₄NiO m/z = 622.13.

(2 H, d, J 4.9, b-H), 9.24 (1 H, dd, J 17.1, J 11.0, alkene-H),

3

8.91 (2 H, d, J 4.9, b-H), 8.81 (4 H, br s, b-H), 8.21 (6 H, m,

o-Ph–H), 7.76 (9 H, m, m,p-Ph–H), 6.54 (1 H, dd, ³J 11.0, ²J 1.8,

alkene-H, trans to porphyrin), 6.15 (1 H, dd, ³J 17.1, ²J 1.8, alkene-

H, cis to porphyrin), −2.68 (2 H, br s, N–H); UV–vis: k_max(log e)

421 (5.23), 519 (3.79), 554 (3.52), 651 (3.14) nm. HRMS (ESI⁺)

m/z = 565.2389. Calc. MH⁺for C₄₀H₂₉N₄m/z = 565.2392.

5,15-Bis(3,5-di-tert-butylphenyl)porphyrinatonickel(II)

(Ni4).

The method was adapted from a procedure reported for similar

porphyrins by Arnold et al.³⁷Porphyrin H₂4 (500 mg, 0.73 mmol)

and nickel(II) acetylacetonate (205 mg, 0.8 mmol) were added to

a 100 cm³ﬂask equipped with a condenser, dissolved in toluene

(50 cm³) and reﬂuxed for 3 h. The progress of the reaction was

monitored by TLC using CH₂Cl₂–n-hexane (50 : 50). Upon

completion of the reaction, the solvent was removed by vacuum

and the product was isolated after passage through a plug of silica

gel using CHCl₃as the eluent. Recrystallisation of the dark red

residue using CHCl₃–MeOH yielded a red crystalline material

Synthesis of alkenylporphyrins

5-Ethenyl-10,15,20-triphenylporphyrinatonickel(II) (Ni8).

Method 1¹¹. Methyltriphenylphosphonium bromide (357 mg,

1.00 mmol) was added to a 100 cm³round-bottom ﬂask equipped

with a side-arm gas adapter and dried under vacuum before the

vessel was purged with argon. Dry, deoxygenated THF (10 cm³)

was added and the mixture was allowed to stir for 5 min at

room temperature to create a suspension of the phosphonium

salt. Butyllithium (0.6 cm³, 1.6 M) was added dropwise to the

slurry via a syringe, resulting in a bright yellow solution. Porphyrin

Ni3 (200 mg, 0.32 mmol) was dissolved in dry, oxygen-free THF

(20 cm³) and added dropwise through a syringe to the freshly made

ylide. The solution turned from purple to red over a period of 2 h

and was monitored by TLC using CHCl₃–n-hexane (50 : 50) as the

eluent. Upon the complete consumption of the starting material,

the reaction was quenched by the addition of H₂O, followed by

extraction with CHCl₃. The CHCl₃layer was washed with water

(50 cm³× 2) and dried using Na₂SO₄before being concentrated

in vacuo. The red residue was puriﬁed by column chromatography

using CHCl₃–n-hexane (50 : 50) as eluent. The fractions containing

Ni8 were collected, dried and recrystallised from CHCl₃–MeOH

to yield red crystals (128 mg, 65%).

3

(535 mg, 98%). d_H9.94 (2 H, s, meso-H), 9.19 (4 H, d, J 4.6,

3

4

b-H), 9.00 (4 H, d, J, b-H), 7.95 (4 H, d, J 1.8, o-Ar–H), 7.78

4

t

(2 H, t, J 1.8, p-Ar–H), 1.52 (36 H, s, Bu–H), −2.98 (2 H, s,

N–H); UV–vis: k_max(log e) 403 (5.13), 515 (4.09), 546 (3.87) nm.

HRMS (LSIMS⁺) m/z = 742.3533. Calc. M⁺for C₄₈H₅₂N₄Ni

m/z = 742.3545. Although this porphyrin has been synthesised

previously,^38,39no spectroscopic data were reported.

5,15-Dibromo-10,20-bis(3,5-di-tert-butylphenyl)porphyrinato-

nickel(II) (Ni6). This was prepared as described above for Ni4,

using porphyrin H₂6 (50 mg, 0.059 mmol) and Ni(acac)₂(16 mg,

0.063 mmol). Recrystallisation of the product using CHCl₃–

MeOH yielded a purple-red powder (53 mg, 99%). d_H9.45 (2 H,

3

4

d, J 4.9, b-H), 8.77 (2 H, d, J 4.9, b-H), 7.80 (4 H, d, J 1.8,

t

o-Ar–H), 7.74 (2 H, t, p-Ar–H), 1.56 (36 H, s, Bu–H); UV–vis:

k_max(log e) 422 (5.13), 536 (4.08). The data were in agreement with

Method 2. Porphyrin H₂8 (100 mg, 0.16 mmol) and Ni(acac)₂

(48 mg, 0.19 mmol) were added to a 50 cm³ﬂask, dissolved in

toluene (20 cm³) and reﬂuxed for 3 h. The progress of the reaction

was monitored by TLC using CH₂Cl₂–n-hexane (50 : 50). Upon

completion of the reaction, the solvent was removed by vacuum

and the product was isolated after passage through a plug of silica

gel using CHCl₃as the eluent. Recrystallisation of the product

from CHCl₃–MeOH yielded red crystals (109 mg, 99%). d_H9.35

(2 H, d, J 5.1, b-H), 8.94 (1 H, dd, J 17.4, J 11.2, alkene-H),

8.81 (2 H, d, ³J 4.9, b-H), 8.70 (2 H, d, ³J 5.1, b-H), 8.68 (2 H, ³J

4.9, b-H), 7.99 (6 H, m, o-Ph–H), 7.68 (9 H, m, m,p-Ph–H), 6.32

(1 H, dd, ³J 11.2, ²J 1.7, alkene-H, trans to porphyrin), 5.65 (1 H,

dd, ³J 17.4, ²J 1.7, alkene-H, cis to porphyrin); UV–vis: k_max(log

e) 418 (5.18), 532 (4.03) nm. MS (LDI⁺) m/z = 620.10. Calc. M⁺

for C₄₀H₂₆N₄Ni m/z = 620.15.

previous work.⁴⁰

5-Formyl-10,20-bis(3,5-di-tert-butylphenyl)porphyrinatonickel

(II) (Ni7). This was prepared from Ni4 as described above for

Ni3. The dark purple crude product was subjected to column

chromatography using CHCl₃–n-hexane (75 : 25) as the eluent.

Fractions containing Ni7 were collected and recrystallised from

CHCl₃–MeOH to yield purple crystals (380 mg, 73%). d_H12.16

(1 H, s, aldehyde), 9.89 (2 H, d, ³J 4.9, b-H), 9.75 (1 H, s, meso-H),

3

9.07 (2 H, d, J 4.7, b-H), 8.97 (2 H, d, J 4.9, b-H), 8.80 (2 H,

d, ³J 4.7, b-H), 7.86 (4 H, d, ⁴J 1.8, o-Ar–H), 7.79 (2 H, t, ⁴J 1.8,

p-Ar–H), 1.53 (36 H, s, ^tBu–H); UV–vis: k_max(log e) 420 (5.19), 545

(3.81), 590 (4.06). Although this compound has been synthesised

previously,^39,41no spectroscopic data were described.

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5-Ethenyl-10,20-bis(3,5-di-tert-butylphenyl)porphyrinatonickel-

(II) (Ni13). This compound was prepared as described above for

Ni8, starting with Ni7. The red residue was puriﬁed by column

chromatography using CHCl₃–n-hexane (50 : 50) as the eluent. The

fractions containing Ni13 were collected, dried and recrystallised

from CHCl₃–MeOH to produce a red crystalline material (129 mg,

E -5-(2-Methoxycarbonylethenyl)-10,15,20-triphenylporphyri-

natonickel(II) (Ni9). Produced from Ni2 (19.7 mg) and methyl

acrylate (130 lL). The product was puriﬁed by column chro-

matography using CHCl₃–n-hexane (50 : 50) as the eluent. The

ﬁrst band from the column corresponded to Ni1, which resulted

from debromination (1.4 mg, 8%). The second band contained the

desired product Ni9 which was recrystallised using CHCl₃–MeOH

to yield dark red crystalline plates (17.5 mg, 89%). d_H9.90 (1 H,

3

65%). d_H9.73 (1 H, s, meso-H), 9.39 (2 H, d, J 4.8, b-H), 9.08

(2 H, d, ³J 4.8, b-H), 8.99 (1 H, dd, ³J 15.6 (trans), ³J^ꢀ11.0 (cis),

alkene-H), 8.89 (2 H, d, ³J 4.8, b-H), 8.88 (2 H, d, ³J 4.8, b-H), 7.88

(4 H, d, ⁴J 1.8, o-Ar–H), 7.74 (2 H, t, p-Ar–H), 6.34 (1 H, dd, ³J

11.0, ²J 1.8, cis alkene-H), 5.70 (1 H, dd, ³J 15.6, ²J 1.8, alkene-H),

3

d, J 15.6, alkene-H), 9.37 (2 H, d, J 4.9, b-H), 8.81 (2 H, d, J

3

4.9, b-H), 8.67 (2 H, d, J 4.9, b-H), 8.63 (2 H, d, J 4.9, b-H),

7.96 (6 H, m, o-Ph–H), 7.68 (9 H, m, m,p-Ph–H), 6.32 (1 H, d,

³J 15.6, alkene-H), 3.97 (3 H, s, CH₃); UV–vis: k_max(log e) 430

(5.23), 545 (4.09), 589 (3.92); MS (LDI⁺) m/z = 678.27. Calc. M⁺

for C₄₂H₂₈N₄NiO₂m/z = 678.15; Found: C, 74.0; H, 4.1; N, 8.25.

Calc. for C₄₂H₂₈N₄NiO₂: C, 74.25; H, 4.15; N, 8.25%.

t

1.50 (36 H, s, Bu–H); UV–vis: k_max(log e) 415 (5.21), 529 (4.07)

nm. MS (LDI⁺) m/z = 768.39. Calc. M⁺for C₅₀H₅₄N₄Ni m/z =

768.37.

Synthesis of alkenyl porphyrins by Heck coupling

E-5-(2-Methoxycarbonylethenyl)-10,15,20-triphenylporphyrina-

tozinc(II) (Zn9). Produced from Zn2 (19.7 mg) and methyl

acrylate (130 lL). The product was puriﬁed by column chro-

matography using CHCl₃–n-hexane (75 : 25) as the eluent. The

ﬁrst band from the column contained Zn1 (2.6 mg, 15%), which

resulted from debromination. The second band contained the

desired product Zn9 which was recrystallised using CHCl₃(1%

pyridine)–MeOH, yielding bright purple plates (15.9 mg, 80%). d_H

10.39 (1 H, d, ³J 15.6, alkene-H), 9.53 (2 H, d, ³J 4.6, b-H), 8.93

(2 H, d, J 4.6, b-H), 8.81 (2 H, d, J 4.6, b-H), 8.79 (2 H, d, J

4.6, b-H), 8.16 (6 H, m, o-Ph–H), 7.72 (9 H, m, m,p-Ph–H), 6.78

(1 H, d, ³J 15.6, alkene-H), 4.04 (3 H, s, CH₃); UV–vis: k_max(log

e) 431 (5.28), 560 (3.97), 608 (3.80) nm. MS (LDI⁺) m/z = 684.31.

Calc. M⁺for C₄₂H₂₈N₄O₂Zn m/z = 684.15; Found: C, 72.8; H, 4.7;

N, 8.00. Calc. for C₄₂H₂₈N₄O₂Zn: C, 73.5; H, 4.1; N, 8.2%.

Several conditions were tested for Heck coupling involving meso-

bromo and meso-ethenyl porphyrins (see text). The conditions that

produced the optimum yield of the Heck-coupled dyads were also

employed for the monoporphyrin couplings described below.

General procedure for mono(alkenyl)porphyrins

Bromoporphyrin (0.029 mmol), palladium acetate (1.5 mg,

0.0058 mmol, 20 mol%), 2-(di-tert-butylphosphino)biphenyl

(4.3 mg, 0.015 mmol) and K₂CO₃(6.5 mg, 0.036 mmol) were

added to a Schlenk tube and dried under vacuum. The vacuum was

released under argon to allow the addition of dry DMF (1.5 cm³),

dry toluene (1.5 cm³) and the vinyl reagent (50-fold excess). The

mixture was then degassed via three freeze–pump–thaw cycles

before the vessel was purged with argon again. The Schlenk ﬂask

was sealed and heated to 105 ^◦C and allowed to stir for 15 h. The

progress of each reaction was monitored by TLC using CH₂Cl₂–

n-hexane (50 : 50) for free-base porphyrins and CHCl₃–n-hexane

(50 : 50) for metallated porphyrins. In monitoring the progress

of the reactions, the heat source was removed for the duration

of the sampling, and in the cases where highly volatile reagents

were used, the reactions were chilled to 0 ^◦C to prevent loss of the

reagent. Upon the complete conversion of the starting material,

the mixture was diluted with toluene (10 cm³) and washed with

water (10 cm³× 2). The organic layer was collected, dried and the

residue was subjected to column chromatography. This procedure

was used to produce the following compounds.

3

E-5-(2-Phenylethenyl)-10,15,20-triphenylporphyrin

(H₂10).

Produced from H₂2 (17.8 mg) and styrene (137 lL). The product

was puriﬁed by column chromatography using CH₂Cl₂–n-hexane

(50 : 50) as the eluent. Porphyrin H₂10 eluted ﬁrst and was

recrystallised using CH₂Cl₂–MeOH (15.9 mg, 87%). d_H9.68 (1 H,

3

d, J 15.9, alkene-H), 9.51 (2 H, d, J 4.9, b-H), 8.89 (2 H, d,

³J 4.9, b-H), 8.80 (2 H, br s, b-H), 8.21 (6 H, m, o-Ph–H), 7.97

(2 H, d, J 7.8, o-phenylethenyl-H), 7.77 (9 H, m, m,p-Ph–H),

3

7.60 (2 H, t, J 7.3, m-phenylethenyl-H), 7.47 (1 H, t, J 7.3,

p-phenylethenyl-H), 7.41 (1 H, d, ³J 15.9, alkene-H), −2.52 (2 H,

br s, N–H); UV–vis: k_max(log e) 427 (5.26), 524 (3.88), 566 (3.94),

599 (3.54), 660 (3.58) nm. HRMS (ESI⁺) m/z = 641.4168. Calc.

MH⁺for C₄₆H₃₂N₄m/z = 641.2705. A second fraction was

collected, H₂1, which resulted from debromination of the starting

material (1.6 mg, 10%).

E-5-(2-Methoxycarbonylethenyl)-10,15,20-triphenylporphyrin

(H₂9). Produced from H₂2 (17.8 mg) and methyl acrylate

(130 lL). The product was puriﬁed by column chromatography

using CH₂Cl₂–n-hexane (50 : 50) as the eluent. The ﬁrst band

from the column corresponded to H₂1, which resulted from

debromination (1.1 mg, 7%). The second band contained the

desired product H₂9 which was recrystallised using CH₂Cl₂–

MeOH to yield a purple semi-crystalline material (15.9 mg, 87%).

d_H10.28 (1 H, d, ³J 15.8, alkene-H), 9.49 (2 H, d, ³J 4.8, b-H), 8.93

E-5-(2-Phenylethenyl)-10,15,20-triphenylporphyrinatonickel(II)

(Ni10). Produced from Ni2 (19.7 mg) and styrene (137 lL).

The product was puriﬁed by column chromatography using

CHCl₃–n-hexane (40 : 60) as the eluent. Porphyrin Ni10 eluted

ﬁrst and was recrystallised from CHCl₃–MeOH to give a bright

3

red crystalline material (17.1 mg, 85%). d_H9.38 (2 H, d, J 4.9,

3

(2 H, d, J 4.8, b-H), 8.81 (2 H, d, J 4.8, b-H), 8.80 (2 H, d, J

4.8, b-H), 8.20 (6 H, m, o-Ph–H), 7.78 (9 H, m, m,p-Ph–H), 6.84

b-H), 9.31 (1 H, d, ³J 15.9, alkene-H), 8.79 (2 H, d, ³J 4.9, b-H),

8.67 (2 H, d, ³J 4.9, b-H), 8.65 (2 H, d, ³J 4.9, b-H), 7.98 (6 H, m,

3

(1 H, d, J 15.8, alkene-H), 4.07 (3 H, s, CH₃), −2.54 (2 H, br s,

o-Ph–H), 7.80 (2 H, d, J 7.3, o-phenylethenyl-H), 7.67 (9 H, m,

3

N–H); UV–vis: k_max(log e) 424 (5.26), 518 (3.99), 558 (3.82), 589

(3.70), 651 (3.46) nm. HRMS (ESI⁺) m/z = 623.7283. Calc. MH⁺

for C₄₂H₃₀N₄O₂m/z = 623.7213.

m,p-Ph–H), 7.51 (2 H, t, J 7.3, m-phenylethenyl-H), 7.40 (1 H,

3

t, J 7.3, p-phenylethenyl-H), 6.87 (1 H, d, J 15.9, alkene-H);

UV–vis: k_max(log e) 431 (5.20), 544 (4.10), 586 (3.87) nm. MS

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3

(LDI⁺) m/z = 696.19. Calc. M⁺for C₄₆H₃₀N₄Ni m/z = 696.18;

Found: C, 79.0; H, 4.3; N, 7.8. Calc. for C₄₆H₃₀N₄Ni: C, 79.2; H,

4.3; N, 8.0%. A second fraction containing Ni1, resulting from

debromination of the starting material, was also isolated (1.7 mg,

10%).

8.66 (2 H, d, J 5.1, b-H), 7.97 (6 H, m, o-Ph–H), 7.69 (9 H, m,

m,p-Ph–H), 6.35 (1 H, d, ³J 16.4, alkene-H).

E -5-(2-Cyanoethenyl)-10,15,20-triphenylporphyrinatozinc(II)

(Zn11) and Z-5-(2-cyanoethenyl)-10,15,20-triphenylporphyrina-

tozinc(II) (Zn12). Produced from Zn2 (19.7 mg) and acrylonitrile

(95 lL). The products were puriﬁed by column chromatography

using CHCl₃–n-hexane (50 : 50) as the eluent. Porphyrin Zn1,

resulting from debromination, eluted ﬁrst (3.1 mg, 18%). The

second fraction was collected and recrystallised using CHCl₃(1%

pyridine)–MeOH, yielding a bright purple powder. NMR studies

showed the presence of two compounds, Zn11 (ca. 90%, NMR)

and Zn12 (ca. 10%), which could not be separated further (14.7 mg,

78%). MS (LDI⁺) m/z = 651.13. Calc. M⁺for C₄₁H₂₅N₅Zn m/z =

651.14; Zn11: d_H9.94 (1 H, d, ³J 16.1, alkene-H), 9.36 (2 H, d, ³J

E -5-(2-Phenylethenyl)-10,15,20-triphenylporphyrinatozinc(II)

(Zn10). Produced from Zn2 (19.7 mg) and styrene (137 lL). The

product was puriﬁed by column chromatography using CHCl₃–

n-hexane (30 : 70) as the eluent. Porphyrin Zn10 eluted from the

column ﬁrst and was recrystallised using CHCl₃(1% pyridine)–

MeOH to give bright purple plates (15.3 mg, 75%). d_H9.78 (1 H,

3

d, J 15.7, alkene-H), 9.55 (2 H, d, J 4.6, b-H), 8.91 (2 H, d,

³J 4.6, b-H), 8.81 (4 H, br s, b-H), 8.19 (4 H, m, o-Ph–H), 8.16

(2 H, m, o-Ph–H), 7.93 (2 H, d, J 7.3, o-phenylethenyl-H), 7.71

3

4.7, b-H), 8.97 (2 H, d, J 4.7, b-H), 8.92 (2 H, d, J 4.7, b-H),

(9 H, m, m,p-Ph–H), 7.57 (2 H, t, ³J 7.3, m-phenylethenyl-H), 7.43

(1 H, t, ³J 7.3, p-phenylethenyl-H), 6.78 (1 H, d, ³J 15.7, alkene-

H); UV–vis: k_max(log e) 430 (5.27), 559 (3.99), 605 (3.88) nm. MS

(LDI⁺) m/z = 702.21. Calc. M⁺for C₄₆H₃₀N₄Zn m/z = 702.17. A

second fraction containing Zn1, resulting from debromination of

the starting material, was also isolated (2.2 mg, 12.5%).

3

8.89 (2 H, d, J 4.7, b-H), 8.17 (6 H, m, o-Ph–H), 7.77 (9 H, m,

m,p-Ph–H), 6.14 (1 H, d, ³J 16.1, alkene-H); Zn12: d_H9.73 (1 H,

3

d, J 11.5, alkene-H), 9.31 (2 H, d, J 4.7, b-H), 9.00 (2 H, d, J

4.7, b-H), 8.92 (2 H, d, ³J 4.7, b-H), 8.89 (2 H, d, ³J 4.7, b-H), 8.16

(6 H, m, o-Ph–H), 7.72 (9 H, m, m,p-Ph–H), 6.65 (1 H, d, ³J 11.5,

alkene-H).

E-5-(2-Cyanoethenyl)-10,15,20-triphenylporphyrin (H₂11) and

Z-5-(3-cyanoethenyl)-10,15,20-triphenylporphyrin (H₂12). Pro-

duced from H₂2 (17.8 mg) and acrylonitrile (95 lL). The products

were puriﬁed by column chromatography using CH₂Cl₂–n-hexane

(50 : 50) as the eluent. Porphyrin H₂2, resulting from debromina-

tion, eluted ﬁrst (1.2 mg, 8%). The second fraction was collected

and recrystallised using CH₂Cl₂–MeOH, yielding a purple powder.

NMR studies showed the presence of two compounds, H₂11 (ca.

65%, NMR) and H₂12 (ca. 35%), which could not be separated

further (13.7 mg, 81%). HRMS (ESI⁺) m/z = 590.2332. Calc.

General procedure for bis(alkenyl)porphyrins using

dihaloporphyrins

Dibromoporphyrin (0.029 mmol), palladium acetate (3.0 mg,

0.0104 mmol, 20 mol%), di-tert-butylbiphenylphosphine (8.6 mg,

0.03 mmol) and K₂CO₃(13 mg, 0.072 mmol) were added to a

Schlenk tube and dried under vacuum. The vacuum was released

under argon to allow the addition of dry DMF (5 cm³), dry toluene

(10 cm³) and the vinyl reagent (50-fold excess). The mixture was

degassed via three freeze–pump–thaw cycles before the vessel was

purged with argon again. The Schlenk ﬂask was sealed and heated

to 105 ^◦C and allowed to stir for 15 h. The progress of each

reaction was monitored by TLC using CH₂Cl₂–n-hexane (50 :

50) for free-base porphyrins and CHCl₃–n-hexane (50 : 50) for

metallated porphyrins. In monitoring the progress of the reactions,

the heat source was removed for the duration of the sampling,

and in the cases where highly volatile reagents were used, the

reactions were chilled to 0 ^◦C to prevent loss of the reagent. Upon

the complete conversion of the starting material, the mixture was

diluted with toluene (20 cm³) and washed with water (20 cm³× 2).

The organic layer was collected, dried and the residue was puriﬁed

by column chromatography. This procedure was used to produce

the following compounds.

3

MH⁺for C₄₁H₂₇N₅m/z = 590.2345. H₂11 d_H10.01 (1 H, d, J

3

16.4, alkene-H), 9.38 (2 H, d, J 4.6, b-H), 8.95 (2 H, d, J 4.6,

b-H), 8.81 (4 H, br s, b-H), 8.20 (6 H, m, o-Ph–H), 7.78 (9 H,

m, m,p-Ph–H), 6.25 (1 H, d, ³J 16.4, alkene-H), −2.52 (2 H, br s,

3

N–H); H₂12 d_H9.77 (1 H, d, J 11.5, alkene-H), 9.31 (2 H, d, J

3

4.6, b-H), 8.96 (2 H, d, J 4.6, b-H), 8.79 (4 H, br s, b-H), 8.20

(6 H, m, o-Ph–H), 7.78 (9 H, m, m, p-Ph–H), 6.69 (1 H, d, ³J 11.5,

alkene-H), −2.64 (2 H, br s, N–H).

E - 5 -(2-Cyanoethenyl) - 10,15,20- triphenylporphyrinatonickel-

(II) (Ni11) and Z-5-(2-cyanoethenyl)-10,15,20-triphenylporphy-

rinatonickel(II) (Ni12). Produced from Ni2 (19.7 mg) and acry-

lonitrile (95 lL). The products were puriﬁed by column chro-

matography using CHCl₃–n-hexane (50 : 50) as the eluent. Com-

pound Ni1, resulting from debromination, eluted ﬁrst (1.9 mg,

11%). The second fraction was collected and recrystallised using

CHCl₃–MeOH, yielding an orange-red powder. NMR studies

showed the presence of two compounds, Ni11 (ca. 85%, NMR)

and Ni12 (ca. 15%), which could not be separated further (15.8 mg,

85%). HRMS (ESI⁺) m/z = 668.1354. Calc. MNa⁺for C₄₁H₂₅N₅Ni

m/z = 668.1361; Found: C, 76.3; H, 4.6; N, 9.5. Calc. for

C₄₁H₂₅N₅Ni: C, 76.2; H, 3.9; N, 10.8%. Ni11 d_H9.58 (1 H, d,

³J 16.4, alkene-H), 9.23 (2 H, d, ³J 4.9, b-H), 8.82 (2 H, d, ³J 4.9,

E-5-(2-Methoxycarbonylethenyl)-10,20-bis(3,5-di-tert-butyl-

phenyl)porphyrin (H₂14) and E,E-5,15-bis(2-methoxycarbonyl-

ethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyrin (H₂18). Pro-

duced from the reaction between H₂6 (24.5 mg) and methyl

acrylate (260 lL). CH₂Cl₂–n-hexane (50 : 50) was used as the

initial eluent and the ﬁrst fraction was collected. This fraction

corresponded to H₂14 (1.1 mg, 5%), which resulted from debromi-

nation of the intermediate bromo(alkenyl)porphyrin. Once the

ﬁrst fraction was collected, the eluent was changed to neat CH₂Cl₂

and a second fraction (H₂18) was collected and recrystallised from

CH₂Cl₂–MeOH to yield a dark powder (17.8 mg, 72%). H₂14: d_H

3

b-H), 8.68 (2 H, d, J 4.9, b-H), 8.63 (2 H, d, J 4.9, b-H), 7.95

(6 H, m, o-Ph–H), 7.69 (9 H, m, m,p-Ph–H), 5.67 (1 H, d, ³J 16.4,

alkene-H); Ni12 d_H9.47 (1 H, d, ³J 11.5, alkene-H), 9.15 (2 H, d,

³J 4.9, b-H), 8.83 (2 H, d, ³J 4.6, b-H), 8.70 (2 H, d, ³J 5.1, b-H),

3

10.36 (1 H, d, J 15.9, alkene-H), 10.21 (1 H, s, meso-H), 9.54

3

(2 H, d, J 4.9, b-H), 9.31 (2 H, d, J 4.9, b-H), 9.04 (2 H, d,

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³J 4.9, b-H), 9.02 (2 H, d, ³J 4.9, b-H), 8.10 (4 H, d, ⁴J 1.7, o-Ar–H),

7.85 (2 H, t, ⁴J 1.7, p-Ar–H), 6.84 (1 H, d, ³J 15.9, alkene-H), 4.07

(3 H, s, CH₃), 1.57 (overlapping H₂O, s, ^tBu–H), −2.80 (2 H, br s,

N–H). H₂18: found: C, 78.8; H, 7.3; N, 6.5. Calc. for C₅₆H₆₃N₄O₄:

C, 78.6; H, 7.4; N, 6.5; HRMS (ESI⁺) m/z = 855.4837.

Calc. MH⁺for C₅₆H₆₃N₄O₄m/z = 855.4849; d_H10.24 (2 H,

collected. This fraction corresponded to H₂15, which resulted

from debromination of the intermediate bromo(alkenyl)porphyrin

(1.6 mg, 7.5%). Once H₂15 was isolated, the eluent was changed

to CH₂Cl₂–n-hexane (70 : 30) and a second fraction (H₂19)

was collected and recrystallised from CH₂Cl₂–MeOH as a dark

powder (17.8 mg, 69%). H₂15: d_H10.15 (1 H, s, meso-H), 9.76

(1 H, d, ³J 15.9, alkene-H), 9.60 (2 H, d, ³J 4.6, b-H), 9.31

3

d, J 15.7, alkene-H), 9.44 (4 H, d, J 4.9, b-H), 8.92 (4 H, d, J

4.9, b-H), 8.06 (4 H, d, ⁴J 1.7, o-Ar–H), 7.85 (2 H, t, p-Ar–H), 6.84

(1 H, d, ³J 15.9, alkene-H), 4.06 (6 H, s, CH₃), 1.56 (overlapping

3

(2 H, d, J 4.6, b-H), 9.06 (2 H, d, J 4.6, b-H), 9.04 (2 H, d,

³J 4.6, b-H), 8.16 (4 H, d, J 1.5, o-Ar–H), 7.98 (2 H, d, J 7.3,

o-phenylethenyl-H), 7.87 (2 H, t, ⁴J 1.5, p-Ar–H), 7.60 (2 H, t, ³J

7.3, m-phenylethenyl-H), 7.48 (1 H, t, ³J 7.3, p-phenylethenyl-H),

7.44 (1 H, d, ³J 15.9, alkene-H), 1.56 (overlapping H₂O, s, ^tBu–H),

−2.69 (2 H, br s, N–H). H₂19: found: C, 86.2; H, 7.55; N, 6.3.

Calc. for C₆₄H₆₆N₄: C, 86.25; H, 7.5; N, 6.3%. d_H9.63 (2 H, d,

4

3

t

H₂O, s, Bu–H); UV–vis: k_max(log e) 433 (5.24), 533 (3.79), 580

(4.03), 674 (3.75) nm.

E-5-(2-Methoxycarbonylethenyl)-10,20-bis(3,5-di-tert-butyl-

phenyl)porphyrinatonickel(II) (Ni14) and E,E-5,15-bis(2-methoxy-

carbonylethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyrinato-

nickel(II) (Ni18). Produced from the reaction between Ni6

(26.1 mg) and methyl acrylate (260 lL). CHCl₃–n-hexane

(50 : 50) was used as the initial eluent and the ﬁrst fraction

was collected. This fraction corresponded to Ni14 (1.2 mg,

5%), which resulted from debromination of the intermediate

bromo(alkenyl)porphyrin. Once the ﬁrst fraction was isolated, the

eluent was changed to CHCl₃–n-hexane (80 : 20) and a second

fraction (Ni18) was collected and recrystallised from CHCl₃–

MeOH to give a dark powder (18.5 mg, 70%). Ni14: d_H9.77 (1 H,

d, ³J 15.6, alkene-H), 9.71 (1 H, s, meso-H), 9.40 (2 H, d, ³J 4.8,

b-H), 9.07 (2 H, d, ³J 4.8, b-H), 8.91 (2 H, d, ³J 4.8, b-H), 8.84 (2 H,

d, ³J 4.8, b-H), 7.85 (4 H, d, ⁴J 1.8, o-Ar–H), 7.75 (2 H, t, ⁴J 1.8,

p-Ar–H), 6.36 (1 H, d, ³J 15.6, alkene-H), 3.97 (3 H, s, CH₃), 1.50

3

³J 15.9, alkene-H), 9.46 (4 H, d, J 4.6, b-H), 8.89 (4 H, d, J

4

3

4.6, b-H), 8.09 (4 H, d, J 1.5, o-Ar–H), 7.96 (4 H, d, J 7.6,

3

o-phenylethenyl-H), 7.83 (2 H, t, p-Ar–H), 7.58 (4 H, d, J 7.6,

m-phenylethenyl-H), 7.46 (2 H, d, ³J 7.6, p-phenylethenyl-H),

7.46 (1 H, d, ³J 15.9, alkene-H), 1.56 (overlapping H₂O, s, ^tBu–H),

−2.20 (2 H, s, N–H); UV–vis: k_max(log e) 437 (5.31), 535 (3.79),

584 (4.16), 677 (3.83) nm.

E-5-(2-Phenylethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphy-

rinatonickel(II) (Ni15) and E,E-5,15-bis(2-phenylethenyl)-10,20-

bis(3,5-di-tert-butylphenyl)porphyrinatonickel(II)

(Ni19). Pro-

duced from the reaction between Ni6 (26.1 mg) and styrene (275

lL). CHCl₃–n-hexane (20 : 80) was used as the initial eluent and

the ﬁrst fraction was collected. This fraction corresponded to

Ni15, which resulted from debromination of the intermediate

bromo(alkenyl)porphyrin (1.2 mg, 5%). Once the ﬁrst fraction

was isolated, the eluent was changed to neat CHCl₃and a second

fraction was collected (Ni19), which was recrystallised from

CHCl₃–MeOH as a dark powder (19.2 mg, 70%). Ni15: d_H9.77

t

(36 H, s, Bu–H), −2.80 (2 H, br s, N–H). Ni18: HRMS (ESI⁺)

m/z = 910.4014. Calc. M⁺for C₅₆H₆₀N₄O₄Ni m/z = 910.3968;

found: C, 73.75; H, 6.8; N, 6.2. Calc. for C₅₆H₆₀N₄O₄Ni: C, 73.8;

H, 6.6; N, 6.1%; d_H9.81 (2 H, d, ³J 15.6, alkene-H), 9.30 (4 H, d, ³J

4.9, b-H), 8.78 (4 H, d, ³J 4.9, b-H), 7.79 (4 H, d, ⁴J 1.8, o-Ar–H),

7.74 (2 H, t, ⁴J 1.8, p-Ar–H), 6.30 (1 H, d, ³J 15.6, alkene-H), 3.95

(6 H, s, CH₃), 1.49 (36 H, s, ^tBu–H); UV–vis: k_max(log e) 441 (5.18),

569 (3.97), 616 (4.20) nm.

3

(1 H, d, J 16.1, alkene-H), 9.64 (1 H, s, meso-H), 9.44 (2 H,

3

d, J 4.9, b-H), 9.38 (2 H, d, J 4.7, b-H), 9.07 (2 H, d, J 4.9,

3

4

b-H), 8.90 (2 H, d, J 4.7, b-H), 7.89 (4 H, d, J 1.8, o-Ar–H),

7.82 (2 H, d, J 7.6, o-phenylethenyl-H), 7.76 (2 H, t, J 1.8,

p-Ar–H), 7.52 (2 H, t, J 7.6, m-phenylethenyl-H), 7.40 (1 H, J

7.6, p-phenylethenyl-H), 6.94 (1 H, d, J 16.1, alkene-H), 1.50

3

4

3

E,E-5,15-Bis(2-methoxycarbonylethenyl)-10,20-bis(3,5-di-tert-

butylphenyl)porphyrinatozinc(II) (Zn18). Produced as the main

product from the reaction between Zn6 (26.3 mg) and methyl

acrylate (230 lL). The product was puriﬁed by column chromatog-

raphy using CHCl₃–n-hexane (50 : 50) as the eluent. After the ﬁrst

band, which consisted of a number of unidentiﬁed porphyrins

(5.1 mg), eluted from the column, the solvent was changed to

CHCl₃–MeOH (99 : 1), and the second fraction (Zn18) was

collected and recrystallised from CHCl₃(1% pyridine)–MeOH as a

dark green powder (18.4 mg, 69%). HRMS (ESI⁺) m/z = 916.3996.

Calc. MH⁺for C₅₆H₆₀N₄O₄Zn m/z = 916.3906; found: C, 73.3; H,

6.6; N, 6.1. Calc. for C₅₆H₆₀N₄O₄Zn: C, 73.2; H, 6.6; N, 6.1%; d_H

10.22 (2 H, d, ³J 15.8, alkene-H), 9.53 (4 H, d, ³J 4.8, b-H), 9.04

3

t

(overlapping H₂O, s, Bu–H). Ni19: found: C, 81.3; H, 6.9; N,

5.9. Calc. for C₆₄H₆₄N₄Ni: C, 81.1; H, 6.8; N, 5.9%. d_H9.30 (4 H,

3

d, J 4.9, b-H), 9.23 (2 H, d, J 16.1, alkene-H), 8.74 (4 H, d,

³J 4.9, b-H), 7.82 (4 H, d, J 1.8, o-Ar–H), 7.78 (4 H, d, J 7.6,

o-phenylethenyl-H), 7.71 (2 H, t, ⁴J 1.8, p-Ar–H), 7.49 (2 H, t, ³J

7.6, m-phenylethenyl-H), 7.37 (2 H, t, ³J 7.6, p-phenylethenyl-H),

6.84 (1 H, d, J 16.1, alkene-H), 1.48 (36 H, s, Bu–H); UV–vis:

k_max(log e) 447 (5.22), 569 (4.04), 616 (4.23) nm.

4

3

t

E,E-5,15-Bis(2-phenylethenyl)-10,20-(3,5-di-tert-butylphenyl)

porphyrinatozinc(II) (Zn19). Produced as the main product from

the reaction between Zn6 (26.3 mg) and styrene (275 lL). The

product was puriﬁed by column chromatography using CHCl₃–n-

hexane (40 : 60) as the eluent. After the ﬁrst band, which consisted

of a number of unidentiﬁed porphyrins (7.5 mg), eluted from

the column, the solvent was changed to pure CHCl₃, and the

second fraction was collected and recrystallised from CHCl₃(1%

pyridine)–MeOH to yield Zn19 as a dark powder (16.6 mg, 60%).

Found: C, 80.5; H, 6.8; N, 5.9. Calc. for C₆₄H₆₄N₄Zn: C, 80.5; H,

6.8; N, 5.9%; d_H9.69 (2 H, d, ³J 15.8, alkene-H), 9.60 (4 H, d, ³J

4.8, b-H), 9.02 (4 H, d, ³J 4.8, b-H), 8.10 (4 H, d, ⁴J 1.8, o-Ar–H),

3

4

(4 H, d, J 4.8, b-H), 8.08 (4 H, d, J 1.8, o-Ar–H), 7.95 (2 H, t,

p-Ar–H), 6.73 (1 H, d, ³J 15.8, alkene-H), 3.97 (6 H, s, CH₃), 1.57

(36 H, s, Bu–H); UV–vis: k_max(log e) 439 (5.28), 571 (2.76), 629

t

(4.04).

E-5-(2-Phenylethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphy-

rin (H₂15) and E,E-5,15-bis(2-phenylethenyl)-10,20-bis(3,5-di-tert-

butylphenyl)porphyrin (H₂19). Produced from the reaction

between H₂6 (24.5 mg) and styrene (275 lL). CH₂Cl₂–n-hexane

(30 : 70) was used as the initial eluent and the ﬁrst fraction was

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3

4

3

7.96 (4 H, d, J 7.7, o-phenylethenyl-H), 7.82 (2 H, t, p-Ar–H),

d, J 2.0, o-Ar–H), 7.85 (2 H, d, J 2.0, p-Ar–H), 6.29 (1 H, d,

³J 16.4, alkene-H), 1.56 (overlapping H₂O, s, ^tBu–H). Once Zn16

was isolated, the eluent was changed to neat CHCl₃and a second

fraction was collected. NMR studies showed the presence of two

isomers, Zn21 (ca. 90%, NMR), and Zn22 (ca. 10%), which could

not be separated further. This fraction was recrystallised from

CHCl₃(1% pyridine)–MeOH, yielding a dark powder (15.8 mg,

64%). MS (LDI⁺) m/z = 850.25. Calc. M⁺for C₅₄H₅₄N₆Zn m/z =

3

7.58 (4 H, t, J 7.7, m-phenylethenyl-H), 7.46 (2 H, t, J 7.7, p-

phenylethenyl-H), 7.41 (1 H, d, ³J 15.8, alkene-H), 1.52 (36 H, s,

^tBu–H); UV–vis: k_max(log e) 440 (5.31), 569 (3.91), 621 (4.11) nm.

E-5-(2-Cyanoethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphy-

rinatonickel(II) (Ni16), Z-5-(2-cyanoethenyl)-10,20-bis(3,5-di-

tert-butylphenyl)porphyrinatonickel(II) (Ni17), E,E-5,15-bis(2-

cyanoethenyl) - 10,20 - bis(3,5 - di - tert - butylphenyl)porphyrinato-

nickel(II) (Ni20), E,Z-5,15-bis(2-cyanoethenyl)-10,20-bis(3,5-di-

tert-butylphenyl)porphyrinatonickel(II) (Ni21) and Z,Z-5,15-bis(2-

cyanoethenyl) - 10,20 - bis(3,5 - di - tert - butylphenyl)porphyrinato-

nickel(II) (Ni22). This mixture was produced from the reaction

between Ni6 (26.1 mg) and acrylonitrile (190 lL). The crude

product was treated by column chromatography using CHCl₃–n-

hexane (70 : 30) as the eluent. The ﬁrst fraction was collected, and

NMR showed it to be a mixture of Ni16 and Ni17, resulting from

debromination of the starting material. These two compounds

could not be separated further. Ni16 (ca. 75%, NMR): d_H9.73

3

850.4. Zn21: d_H9.99 (2 H, d, J 16.1, alkene-H), 9.36 (4 H, d,

³J 4.7, b-H), 8.95 (4 H, d, J 4.7, b-H), 8.09 (4 H, overlapped,

3

o-Ar–H), 7.83 (2 H, overlapped, p-Ar–H), 6.04 (2 H, d, J 16.1,

alkene-H), 1.56 (overlapping H₂O, s, ^tBu–H). Zn22: d_H10.02 (2 H,

d, ³J 16.4, alkene-H), 9.77 (1 H, d, ³J 10.5, alkene-H), 9.39 (2 H,

3

d, J 4.6, b-H), 9.34 (2 H, d, J 4.9, b-H), 8.96 (2 H, d, J 4.6,

b-H), 8.94 (2 H, d, ³J 4.9, b-H), 7.94 (4 H, overlapped, o-Ar–H),

7.81 (2 H, overlapped, p-Ar–H), 6.66 (1 H, d, ³J 10.5, alkene-H),

6.13 (1 H, d, ³J 16.4, alkene-H), 1.56 (overlapped, s, ^tBu–H).

General procedure for Heck coupling using vinylporphyrins

3

(1 H, s, meso-H), 9.68 (1 H, d, J 16.2, alkene-H), 9.30 (2 H,

d, J 5.0, b-H), 9.07 (2 H, d, J 4.8, b-H), 8.93 (2 H, d, J 5.0,

3

Vinylporphyrin (0.019 mmol), palladium acetate (1.0 mg,

0.004 mmol, 20 mol%), triphenylphosphine (2.6 mg, 0.01 mmol)

and K₂CO₃(4.3 mg, 0.024 mmol) were added to a Schlenk

tube and dried under vacuum. The vacuum was released under

argon to allow the addition of dry DMF (1 cm³), dry toluene

(1 cm³) and the halogen reagent (50-fold excess). The mixture

was degassed via three freeze–pump–thaw cycles before the vessel

was purged with argon again. The Schlenk ﬂask was sealed and

heated to 105 ^◦C and allowed to stir for 48 h. Each reaction was

monitored by TLC using CHCl₃–n-hexane (50 : 50). After 48 h,

the mixture was diluted with toluene (10 cm³) and washed with

water (10 cm³× 2). The organic layer was collected, dried and

the residue was subjected to column chromatography. The bands

containing the desired porphyrins were collected and recrystallised

using CHCl₃–MeOH. This procedure was used to produce the

following compounds.

3

b-H), 8.84 (2 H, d, J 4.8, b-H), 7.82 (4 H, d, J 1.7, o-Ar–H),

7.76 (2 H, overlapped, p-Ar–H), 5.75 (2 H, d, ³J 16.2, alkene-H),

t

1.48 (overlapped, s, Bu–H); Ni17 (ca. 25%): d_H9.79 (1 H, s,

3

meso-H), 9.58 (1 H, d, J 11.6, alkene-H), 9.22 (2 H, d, J 5.0,

b-H), 9.11 (2 H, d, ³J 4.8, b-H), 9.00 (2 H, d, ³J 5.0, b-H),

3

8.88 (2 H, d, J 4.8, b-H), 7.86 (4 H, d, J 1.7, o-Ar–H), 7.76

(2 H, overlapped, p-Ar–H), 6.44 (2 H, d, ³J 11.6, alkene-H), 1.48

t

(36 H, s, Bu–H). The major second band was collected and the

residue was recrystallised using CHCl₃–MeOH to yield a dark

powder. NMR studies showed the presence of three isomers, Ni20

(ca. 65%, NMR), Ni21 (ca. 25%) and Ni22 (ca. 10%), which could

not be separated further (total 17.5 mg, 72%). HRMS (ESI⁺)

m/z = 844.3770, 845.3814, 867.3665. Calc. M⁺, MH⁺, MNa⁺for

C₅₄H₅₄N₆Ni m/z = 844.3763, 845.3842, 867.3661, respectively;

3

Ni20: d_H9.50 (2 H, d, J 16.2, alkene-H), 9.19 (4 H, d, J 4.9,

b-H), 8.80 (4 H, d, ³J 4.9, b-H), 7.76 (4 H, overlapped, o-Ar–H),

7.74 (2 H, overlapped, p-Ar–H), 5.69 (2 H, d, ³J 16.2, alkene-H),

5 - (1 - Phenylethenyl) - 10,15,20 - triphenylporphyrinatonickel(II)

(23). Produced from the reaction between Ni8 (11.9 mg) and

iodobenzene (106 lL). The product was puriﬁed by column

chromatography using CHCl₃–n-hexane (10 : 90). The ﬁrst fraction

contained unreacted starting material (2.0 mg, 17%). The second

fraction contained the expected product Ni10 (7.2 mg, 54%). The

third fraction contained 23 (2.7 mg, 20%). HRMS (ESI⁺) m/z =

696.1827. Calc. M⁺for C₄₆H₃₀N₄Ni m/z = 696.1824; d_H9.10 (2

t

3

1.48 (36 H, s, Bu–H); Ni21: d_H9.55 (1 H, d, J 16.2, alkene-H),

9.43 (1 H, d, ³J 11.6, cis-alkene-H), 9.29 (2 H, d, ³J 4.9, b-H), 9.12

3

(2 H, d, J 4.9, b-H), 8.83 (2 H, d, J 4.9, b-H), 8.79 (2 H, d, J

4.9, b-H), 7.76 (4 H, overlapped, o-Ar–H), 7.74 (2 H, overlapped,

p-Ar–H), 6.36 (1 H, d, ³J 11.6, cis-alkene-H), 5.37 (1 H, d, ³J 16.2,

t

3

alkene-H), 1.48 (36 H, s, Bu–H); Ni22: d_H9.44 (2 H, d, J 11.9,

3

alkene-H), 9.15 (4 H, d, J 4.9, b-H), 8.77 (4 H, d, J 4.9, b-H),

7.76 (4 H, overlapped, o-Ar–H), 7.74 (2 H, overlapped, p-Ar–H),

6.39 (2 H, d, ³J 11.6, alkene-H), 1.48 (36 H, s, ^tBu–H).

3

H, d, J 5.1, b-H), 8.73 (2 H, d, J 5.1, b-H), 8.73 (4 H, br s,

b-H), 8.00 (6 H, m, o-Ph–H), 7.67 (9 H, m, m,p-Ph–H), 7.43 (2 H,

m, o-phenylethenyl-H), 7.23 (3 H, m, m,p-phenylethenyl-H), 6.83

(1 H, d, ²J 1.1, alkene-H (cis to porphyrin)), 5.91 (1 H, d, ²J 1.1,

alkene-H (trans to porphyrin)). Once 27 eluted from the column,

the solvent was changed to neat CHCl₃and a fourth fraction was

collected. NMR studies showed it to be the aldehyde Ni3 (<1 mg,

∼5%).

E-5-(2-Cyanoethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphy-

rinatozinc(II) (Zn16), E,E-5,15-bis(2-cyanoethenyl)-10,20-bis(3,5-

di-tert-butylphenyl)porphyrinatozinc(II) (Zn21) and E,Z-5,15-bis-

(2-cyanoethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyrinato-

zinc(II) (Zn22). Produced from the reaction between Zn6

(26.3 mg) and acrylonitrile (190 lL). CHCl₃–n-hexane (60 :

40) was used as the initial eluent and the ﬁrst fraction was

collected. This fraction corresponded to Zn16, which resulted

from debromination of the intermediate bromo(alkenyl)porphyrin

5-(1-Phenylethenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyri-

natonickel(II) (24) and E-2-(2-phenylethenyl)-5,15-bis(3,5-di-tert-

butylphenyl)porphyrinatonickel(II) (25). Produced from the re-

action between Ni13 (14.6 mg) and iodobenzene (106 lL). The

product was puriﬁed by column chromatography using CHCl₃–n-

hexane (10 : 90). The ﬁrst fraction contained unreacted starting

3

(1.9 mg, 8%). Zn16: d_H10.29 (1 H, s, meso-H), 10.15 (1 H, d, J

3

16.4, alkene-H), 9.55 (2 H, d, J 4.9, b-H), 9.41 (2 H, d, J 4.4,

b-H), 9.17 (2 H, d, ³J 4.9, b-H), 9.12 (2 H, d, ³J 4.4, b-H), 8.09 (4 H,

914 | Org. Biomol. Chem., 2006, 4, 902–916

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material Ni13 (3.5 mg, 24%). The second and third fractions

contained mixtures of Ni15, 24, and 25, which could not be

separated further (9.2 mg, 68%). MS (LDI⁺) m/z = 844.94.

Calc. M⁺for C₅₆H₅₈N₄Ni m/z = 844.40. 24: 30% (estimated from

NMR). d_H9.84 (1 H, s, meso-H), 9.16 (2 H, d, ³J 4.9, b-H), 9.14

(2 H, d, ³J 4.9, b-H), 8.93 (2 H, d, ³J 4.9, b-H), 8.84 (2 H, d, ³J 4.9,

b-H), 7.88 (overlapped, o-Ar–H), 7.75 (overlapped, p-Ar–H), 7.42

(overlapped, o-phenylethenyl-H), 7.22(3H, m, m,p-phenylethenyl-

H), 6.85 (1 H, d, ²J 1.1, alkene-H (cis to porphyrin)), 5.94 (1 H, d,

²J 1.1, alkene-H (trans to porphyrin)), 1.51 (36 H, s, ^tBu–H); 25: d_H

10.13 (1 H, s, meso-H), 9.88 (1 H, s, meso-H), 9.21 (1 H, d, ³J 4.7,

b-H), 9.15 (2 H, d, ³J 4.7, b-H), 9.11 (1 H, s, b-H), 8.98 (1 H, d, ³J

4.7, b-H), 8.96 (1 H, d, ³J 4.7, b-H), 8.94 (1 H, d, ³J 4.7, b-H), 8.63

(1 H, d, ³J 16.1, alkene-H), 7.97 (2 H, d, ³J 1.7, o-Ar–H), 7.93 (2 H,

d, ⁴J 1.7, o-Ar–H), 7.83 (2 H, d, ³J 7.6, o-phenylethenyl-H), 7.77

(1 H, t, ⁴J 1.7, p-Ar–H), 7.52 (2 H, t, ³J 7.6, m-phenylethenyl-H),

7.38 (2 H, t, ³J 7.6, o-phenylethenyl), 1.54 (18 H, s, ^tBu–H), 1.52

subjected to column chromatography. This procedure was used to

produce the following compounds.

E-1-[5,15-Bis(3,5-di-tert-butylphenyl)porphyrinatonickel(II)-2-

yl]-2-[(10,15,20-triphenyl)porphyrin-5-yl]ethene (29). Produced

from H₂2 (9.2 mg) as the bromoporphyrin partner. The product

was puriﬁed using CH₂Cl₂–n-hexane (50 : 50) as the eluent. The

ﬁrst band contained unreacted starting material Ni13 (10.5 mg,

71%). The second fraction contained the product 29, which was

recrystallised from CH₂Cl₂–MeOH to give a dark powder (4.4 mg,

23%). HRMS (ESI⁺) m/z = 1305.4376. Calc. MH⁺for C₈₈H₇₉N₈Ni

3

m/z = 1305.4781; d_H10.30 (1 H, d, J 15.4, 2-alkene-H), 10.30

(1 H, s, 20-meso-H, NiDAP), 9.92 (1 H, s, 10-meso-H, NiDAP),

9.80 (2 H, d, ³J 4.7, b-H, H₂TriPP), 9.65 (1 H, s, b-H, NiDAP), 9.22

(1 H, d, ³J 4.9, b-H, NiDAP), 9.19 (1 H, d, ³J 4.9, b-H, NiDAP),

3

9.16 (1 H, d, J 4.9, b-H, NiDAP), 9.07 (1 H, d, J 4.9, b-H,

NiDAP), 9.00 (1 H, d, ³J 4.9, b-H, NiDAP), 8.99 (2 H, d, ³J 4.7,

b-H, H₂TriPP), 8.97 (1 H, d, ³J 4.9, b-H, NiDAP), 8.92 (1 H, d, ³J

15.4, b-H, 1-alkene-H), 8.84 (4 H, br s, b-H, H₂TriPP), 8.28 (4 H,

m, o-Ph–H, H₂TriPP), 8.24 (2 H, m, o-Ph–H, H₂TriPP), 8.18 (2 H,

d, ⁴J 1.7, o-Ar–H, NiDAP), 7.95 (2 H, d, ⁴J 1.7, o-Ar–H, NiDAP),

7.88 (1 H, t, ⁴J 1.7, p-Ar–H, NiDAP), 7.79 (1 H, overlapped, p-Ar–

H, NiDAP), 7.79 (9 H, m, m,p-Ph–H, H₂TriPP), 1.64 (18 H, s, ^tBu–

H, NiDAP), 1.52 (18 H, s, ^tBu–H, NiDAP), −2.30 (2 H, br s, N–H,

H₂TriPP); UV–vis: k_max(log e) 425 (5.30), 522 (4.45), 594 (4.55),

673 (4.23) nm. A third and fourth fraction were also collected,

containing H₂1 (5.8 mg, 72% from H₂2) and Ni7 (<1 mg, ∼5%),

respectively.

t

(18 H, s, Bu–H). The solvent was changed to neat CHCl₃and a

fourth fraction was collected; NMR studies showed it to be Ni7

(<1 mg, ∼5%).

E-5-[2-(Anthracen-9-yl)ethenyl]-10,20-bis(3,5-di-tert-butyl-

phenyl)porphyrinatonickel(II) (26) and E-2-[2-(anthracen-9-yl)-

ethenyl] - 5,15 - bis(3,5 - di - tert - butylphenyl)porphyrinatonickel(II)

(27). Produced from the reaction between Ni13 (14.6 mg)

and 9-bromoanthracene (15 mg, 3.1-fold excess) using 2-P(t-

Bu)₂biphenyl as phosphine ligand. The product mixture was

isolated by column chromatography using CHCl₃–n-hexane (30 :

70) as the eluent. The ﬁrst fraction contained unreacted start-

ing material Ni13 (7.3 mg, 50%), while the second fraction

corresponded to 26, with a minor amount of the b-substituted

analogue 27 and other impurities that could not be removed

by chromatography. This mixture was recrystallised twice from

CHCl₃–MeOH to yield a dark red powder (2.0 mg, 11%). MS

(LDI⁺) m/z = 945.27. Calc. M⁺for C₅₆H₅₈N₄Ni m/z = 945.43. 26:

d_H9.72 (1 H, s, meso-H), 9.61 (2 H, d, ³J 4.9, b-H), 9.29 (1 H, d, ³J

15.9, alkene-H), 9.09 (2 H, d, ³J 4.9, b-H), 8.93 (2 H, d, ³J 4.9, b-H),

8.89 (2 H, d, ³J 4.9, b-H), 8.69 (2 H, m, anthracene-H), 8.53 (2 H, s,

anthracene-H), 8.11 (2 H, m, anthracene-H), 7.89 (4 H, d, ⁴J 1.8,

o-Ar–H), 7.74 (2 H, d, ⁴J 1.8, p-Ar–H), 7.53 (4 H, m, anthracene-

E-1-[5,15-Bis(3,5-di-tert-butylphenyl)porphyrinatonickel(II)-2-

yl]-2-[(10,15,20-triphenyl)porphyrinatonickel(II)-5-yl]ethene (30).

Produced from Ni2 (10.1 mg) as the bromoporphyrin reagent. The

product was puriﬁed by column chromatography using CHCl₃–n-

hexane (50 : 50) as the eluent. The ﬁrst band eluted contained

unreacted starting material Ni13 (10.1 mg, 69%). The second

fraction contained the product 30, which was recrystallised from

CHCl₃–MeOH, yielding a dark powder (6.7 mg, 33%). MS (LDI⁺)

m/z = 1360.54. Calc. M⁺for C₈₈H₇₆N₈Ni₂m/z = 1360.49; d_H10.03

(1 H, s, 20-meso-H, NiDAP), 9.90 (1 H, s, 10-meso-H, NiDAP),

3

9.89 (1 H, d, J 15.7, 2-alkene-H), 9.67 (2 H, d, J 4.9, b-H,

3

t

NiTriPP), 9.54 (1 H, s, b-H, NiDAP), 9.19 (1 H, d, J 4.9, b-H,

H), 7.53 (1 H, d, J 15.9, alkene-H), 1.49 (36 H, Bu–H). The

b-alkenylanthracene 27 could not be fully characterised by NMR

because of the number of overlapping peaks in the spectrum.

NiDAP), 9.16 (1 H, d, ³J 4.9, b-H, NiDAP), 9.05 (1 H, d, ³J 4.9,

b-H, NiDAP), 9.03 (1 H, d, ³J 4.9, b-H, NiDAP), 8.96 (1 H, d, ³J

4.9, b-H, NiDAP), 8.90 (1 H, d, ³J 4.9, b-H, NiDAP), 8.89 (2 H,

d, ³J 4.9, b-H, NiTriPP), 8.70 (2 H, d, ³J 4.9, b-H, NiTriPP), 8.68

(2 H, d, ³J 4.9, b-H, NiTriPP), 8.36 (1 H, d, ³J 15.7, 1-alkene-H,

Preparation of meso,b-porphyrin dyads by Heck coupling.

Porphyrin Ni13 (14.6 mg, 0.019 mmol), bromoporphyrin

(0.015 mmol), palladium acetate (1.0 mg, 0.004 mmol, 20 mol%),

di-tert-butylbiphenylphosphine (3.0 mg, 0.01 mmol) and K₂CO₃

(4.3 mg, 0.024 mmol) were added to a Schlenk tube and dried

under vacuum. The vacuum was released under argon to allow the

addition of dry DMF (1.5 cm³), and dry toluene (1.5 cm³). The

mixture was degassed via three freeze–pump–thaw cycles before

the vessel was purged with argon again. The Schlenk ﬂask was

sealed and heated to 105 ^◦C and allowed to stir for 72 h. Each

reaction was monitored by TLC using CH₂Cl₂–n-hexane (50 :

50) for free base bromoporphyrin and CHCl₃–n-hexane (50 : 50)

for metallated bromoporphyrins. After 72 h, TLC showed the

complete consumption of bromoporphyrin, so the mixture was

diluted with toluene (10 cm³) and washed with water (10 cm³×

2). The organic layer was collected, dried and the residue was

4

NiDAP), 8.13 (2 H, d, J 1.7, o-Ar–H, NiDAP), 8.04 (4 H, m,

o-Ph–H, NiTriPP), 8.01 (2 H, m, o-Ph–H, NiTriPP), 7.90 (2 H, d,

4

⁴J 1.7, o-Ar–H, NiDAP), 7.88 (1 H, t, J 1.7, p-Ar–H, NiDAP),

7.75 (1 H, t, p-Ar–H, NiDAP), 7.70 (9 H, m, m,p-Ph–H, NiTriPP),

t

1.64 (18 H, s, Bu–H, NiDAP), 1.49 (18 H, s, Bu–H, NiDAP);

UV–vis: k_max(log e) 422 (5.29), 458 (5.09, shoulder on Soret band),

526 (4.53), 560 (4.40), 619 (4.47) nm. A third and fourth fraction

were also collected, containing Ni1 (5.2 mg, 65% from Ni2) and

Ni7 (<1 mg, ∼5%), respectively.

E-1-[5,15-Bis(3,5-di-tert-butylphenyl)porphyrinatonickel(II)-2-

yl]-2-[(10,15,20-triphenyl)porphyrinatozinc(II)-5-yl]ethene

(31).

Produced from Zn2 (10.2 mg) as the bromoporphyrin reagent.

The product was puriﬁed by column chromatography using

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CHCl₃–n-hexane (50 : 50) as the eluent. The ﬁrst band eluted

contained unreacted starting material Ni13 (10.1 mg, 69%). The

second fraction contained the product 31, which was recrystallised

from CHCl₃–MeOH to give shiny dark plates (3.1 mg, 15%). MS

(LDI⁺) m/z = 1367.38. Calc. MH⁺for C₈₈H₇₆N₈NiZn m/z =

15 A. K. Burrell and D. L. Ofﬁcer, Synlett, 1998, 1297–1307 and references

cited therein.

16 M. Castella, F. Calahorra, D. Sainz and D. Velasco, Org. Lett., 2001,

3, 541–544.

17 M. Castella, F. Lopez-Calahorra, D. Velsaco and H. Finkelmann, Liq.

´

Cryst., 2002, 29, 559–565.

18 T. E. O. Screen, I. M. Blake, L. H. Rees, W. Clegg, S. J. Borwick and

H. L. Anderson, J. Chem. Soc., Perkin Trans. 1, 2002, 320–329.

19 See, for example: V. V. Borovkov, G. V. Ponomarev, A. Ishida, T. Kaneda

and Y. Sakata, Chem. Lett., 1993, 1409–1412; R. Kitagawa, Y. Kai, G. V.

Ponomarev, K. Sugiura, V. V. Borovkov, T. Kaneda and Y. Sakata,

Chem. Lett., 1993, 1071–1074; G. V. Ponomarev, V. V. Borovkov, K.

Sugiura, Y. Sakata and A. M. Shulga, Tetrahedron Lett., 1993, 34, 2153–

2156; M. O. Senge, M. G. H. Vicente, K. R. Gerzevske, T. P. Forsyth

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Shimizu, J. Ojima, K. Sugiura and Y. Sakata, Tetrahedron Lett., 1995,

36, 5359–5362; D. P. Arnold, V. V. Borovkov and G. V. Ponomarev,

Chem. Lett., 1996, 485–486; M. Chachisvilis, V. S. Chirvony, A. M.

Shulga, B. Ka¨llebring, S. Larsson and V. Sundstro¨m, J. Phys. Chem.,

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13867–13873; H. Higuchi, K. Shimizu, M. Takeuchi, J. Ojima, K. I.

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20 M. J. Frampton, H. Akdas, A. R. Cowley, J. E. Rogers, J. E. Slagle,

P. A. Fleitz, M. Drobizhev, A. Rebane and H. L. Anderson, Org. Lett.,

2005, 7, 5365–5368.

3

1367.49; d_H10.44 (1 H, d, J 15.7, 2-alkene-H), 10.33 (1 H, s,

20-meso-H, NiDAP), 9.92 (1 H, s, 10-meso-H, NiDAP), 9.87 (2 H,

3

d, J 4.7, b-H, ZnTriPP), 9.63 (1 H, s, b-H, NiDAP), 9.23 (1 H,

3

d, J 4.7, b-H, NiDAP), 9.20 (1 H, d, J 4.7, b-H, NiDAP), 9.17

(1 H, d, ³J 4.7, b-H, NiDAP), 9.08 (1 H, d, ³J 4.7, b-H, NiDAP),

9.02 (2 H, d, J 4.7, b-H, ZnTriPP), 9.00 (1 H, d, J 4.7, b-H,

NiDAP), 8.98 (1 H, d, J 4.7, b-H, NiDAP), 8.88 (1 H, d, J

15.7, 1-alkene-H), 8.85 (4 H, br s, b-H, ZnTriPP), 8.26 (4 H, m,

o-Ph–H, ZnTriPP), 8.21 (2 H, m, o-Ph–H, ZnTriPP), 8.18 (2 H, d,

⁴J 1.7, o-Ar–H, NiDAP), 7.95 (2 H, d, ⁴J 1.7, o-Ar–H, NiDAP),

3

4

7.87 (1 H, t, J 1.7, p-Ar–H, NiDAP), 7.75 (1 H, overlapped,

p-Ar–H, NiDAP), 7.75 (9 H, m, m,p-Ph–H, ZnTriPP), 1.63 (18 H,

t

s, Bu–H, NiDAP), 1.52 (18 H, s, Bu–H, NiDAP); UV-vis: k_max

(log e) 425 (5.26), 524 (4.33), 561 (4.39), 620 (4.43) nm. A third

and fourth fraction were also collected, corresponding to Zn1

(7.2 mg, 80% from Zn2) and Ni7 (<1 mg, ∼5%), respectively.

21 O. B. Locos and D. P. Arnold, unpublished results.

22 A. Kato, R. D. Hartnell, M. Yamashita, H. Miyasaka, K.-i. Sugiura

and D. P. Arnold, J. Porphyrins Phthalocyanines, 2004, 8, 1222–1227.

23 R. F. Heck, in Palladium Reagents in Organic Synthesis, ed. R. F. Heck,

Academic Press, London, 1982, pp. 345–389.

Acknowledgements

24 See, for example: V. S.-Y. Lin, S. G. DiMagno and M. J. Therien,

Science, 1994, 264, 1105–1111; V. S. Y. Lin and M. J. Therien, Chem.–

Eur. J., 1996, 1, 645–651; H. L. Anderson, Chem. Commun., 1999,

2323–2330; J. J. Piet, P. N. Taylor, B. R. Wegewijs, H. L. Anderson,

A. Osuka and J. M. Warman, J. Phys. Chem. B, 2001, 105, 97–104;

D. P. Arnold, G. A. Heath and D. A. James, New J. Chem., 1998, 22,

1377–1387; D. P. Arnold, G. A. Heath and D. A. James, J. Porphyrins

Phthalocyanines, 1999, 3, 5–31; G. J. Wilson and D. P. Arnold, J. Phys.

Chem. A, 2005, 109, 6104–6113.

25 S. Braese and A. De Meijere, in Handbook of Organopalladium

Chemistry for Organic Synthesis, ed. E-i. Negishi, John Wiley & Sons,

New York, 2002, vol. 1, pp. 1123–1132.

26 A. Kato, D. P. Arnold, H. Miyasaka, M. Yamashita and K.-i. Sugiura,

manuscript in preparation.

We thank Queensland University of Technology for a post-

graduate scholarship for OBL, and DPA thanks Prof. H. L. An-

derson for provision of data prior to publication.

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The Heck reaction for porphyrin functionalisation: Synthesis of meso-alkenyl monoporphyrins and palladium-catalysed formation of unprecedented meso-β ethene-linked diporphyrins

DOI: 10.1039/b516989e

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