Porphyrins with exocyclic rings. 13. Synthesis and spectroscopic characterization of highly modified porphyrin chromophores with fused acenaphthylene and benzothiadiazole rings

Article abstract of DOI:10.1021/jo9815655

As part of a survey on the influence of fused aromatic rings on the porphyrin chromophore, a series of novel structures with fused acenaphthylene or benzothiadiazole rings have been synthesized. Base-catalyzed condensation of 1-nitroacenaphthylene or 4-nitrobenzothiadiazole with esters of isocyanoacetic acid afforded good yields of the annelated pyrroles 5 and 28. Cleavage of the ester moieties with KOH in refluxing ethylene glycol gave the unsubstituted heterocycles, and subsequent condensation with 2 equiv of acetoxymethylpyrroles 9 in acetic acid/ethanol produced the modified tripyrranes 12 and 31. Tripyrranes with terminal tert-butyl ester units were treated with TFA and condensed with 3,4-diethyl-2,5-pyrroledicarboxaldehyde 13 in dichloromethane to give, following oxidation with DDQ, the corresponding π-extended porphyrins 14 and 32. Acenaphthoporphyrins 14 showed unique UV-vis spectra with a triply split Soret band region and a relatively strong band near 660 nm. Strongly red-shifted absorptions were also noted for the dications and the nickel(II), copper(II), and zinc chelates for this system. Thiadiazoloporphyrins 32 gave two broadened Soret bands, but the Q-band region was unexceptional. However, the nickel(II), copper(II), and zinc complexes all showed abnormally strong absorptions between 600 and 612 nm. Porphyrins with two antipodal fused aromatic rings were easily prepared by condensing c-annelated pyrroledialdehydes 17 with tripyrranes 12 and 31, and the spectroscopic properties of the resulting porphyrins showed that the observed ring-fusion effects were essentially additive. Porphyrins with two adjacent acenaphthylene rings were also prepared by the MacDonald '2 + 2' condensation, although this chemistry gave poor results in the synthesis of a porphyrin with two fused benzothiadiazole rings. The spectroscopic properties of these new highly conjugated porphyrin structures show that ring fusion can profoundly modify the porphyrin chromophore.

Full text of DOI:10.1021/jo9815655

J . Org. Chem. 1998, 63, 8455-8469
8455
P or p h yr in s w ith Exocyclic Rin gs. 13.1 Syn th esis a n d
Sp ectr oscop ic Ch a r a cter iza tion of High ly Mod ified P or p h yr in
Ch r om op h or es w ith F u sed Acen a p h th ylen e a n d Ben zoth ia d ia zole
Rin gs
Timothy D. Lash,* Pushpa Chandrasekar, Augustine T. Osuma, Sun T. Chaney, and
J ohn D. Spence
Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160
Received August 4, 1998
As part of a survey on the influence of fused aromatic rings on the porphyrin chromophore, a series
of novel structures with fused acenaphthylene or benzothiadiazole rings have been synthesized.
Base-catalyzed condensation of 1-nitroacenaphthylene or 4-nitrobenzothiadiazole with esters of
isocyanoacetic acid afforded good yields of the annelated pyrroles 5 and 28. Cleavage of the ester
moieties with KOH in refluxing ethylene glycol gave the unsubstituted heterocycles, and subsequent
condensation with 2 equiv of acetoxymethylpyrroles 9 in acetic acid/ethanol produced the modified
tripyrranes 12 and 31. Tripyrranes with terminal tert-butyl ester units were treated with TFA
and condensed with 3,4-diethyl-2,5-pyrroledicarboxaldehyde 13 in dichloromethane to give, following
oxidation with DDQ, the corresponding π-extended porphyrins 14 and 32. Acenaphthoporphyrins
14 showed unique UV-vis spectra with a triply split Soret band region and a relatively strong
band near 660 nm. Strongly red-shifted absorptions were also noted for the dications and the
nickel(II), copper(II), and zinc chelates for this system. Thiadiazoloporphyrins 32 gave two
broadened Soret bands, but the Q-band region was unexceptional. However, the nickel(II), copper-
(II), and zinc complexes all showed abnormally strong absorptions between 600 and 612 nm.
Porphyrins with two antipodal fused aromatic rings were easily prepared by condensing c-annelated
pyrroledialdehydes 17 with tripyrranes 12 and 31, and the spectroscopic properties of the resulting
porphyrins showed that the observed ring-fusion effects were essentially additive. Porphyrins with
two adjacent acenaphthylene rings were also prepared by the MacDonald “2 + 2” condensation,
although this chemistrry gave poor results in the synthesis of a porphyrin with two fused
benzothiadiazole rings. The spectroscopic properties of these new highly conjugated porphyrin
structures show that ring fusion can profoundly modify the porphyrin chromophore.
Ch a r t 1. P or p h yr in s w ith F u sed Ar om a tic
Su bu n its
In tr od u ction
Porphyrinoid chromophores with strong absorptions in
the far-visible/near-IR region have attracted considerable
attention in recent years due to their intrinsic value in
the development of novel optical materials with potential
applications in optical recording technology.2 In addition,
some porphyrins show a high affinity for tumor cells and
can act as photosensitizers for singlet oxygen formation
in photodynamic therapy (PDT).3 However, light is
strongly absorbed by bodily tissues over much of the
visible region, and this limits clinical applications. Light
penetration is greatest at higher wavelengths (>700 nm),
and for this reason, there has been a great deal of effort
directed at the development of more effective photosen-
sitizers for PDT that absorb between 700 and 800 nm.3
Increased conjugation usually induces a red shift for a
given chromophore, and one might naively expect that
aromatic subunits fused to the porphyrin nucleus (see
Chart 1) would have the desired effect on the chro-
mophores electronic spectra. However, in many cases,
the influence of benzenoid ring fusion on porphyrin UV-
vis absorption spectra is minimal. Solutions of 2,3,7,8,-
12,13,17,18-octaethylporphyrin (OEP) in organic solvents
such as chloroform or benzene show a strong Soret band
at 400 nm, together with a series of Q-bands between
490 and 625 nm (Table 1).4 The longest wavelength
* Corresponding author. E-mail: tdlash@rs6000.cmp.ilstu.edu.
(1) Part 12: Bastian, J . A.; Lash, T. D. Tetrahedron 1998, 54, 6299.
(2) Fabian, J .; Nakazumi, H.; Matsuoka, M. Chem. Rev. 1992, 92,
1197.
(3) Brown, S. B.; Truscott, T. G. Chem. Br. 1993, 29, 955. Bonnett,
R. Chem. Soc. Rev. 1995, 24, 19. Milgrom, L. R.; MacRobert, S. Chem.
Br. 1998, 34 (35), 45.
10.1021/jo9815655 CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/21/1998

8456 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
Ta ble 1. Electr on ic Sp ectr a of OEP a n d Selected
P or p h yr in s w ith On e F u sed Ar om a tic Rin g
Sch em e 1
Q bands
porphyrin
(solvent) (log10 ꢀ) Soret bands
λmax (nm)
IV
III
II
I
OEP4
(Benzene)
15
400
(5.20)
403
(5.47)
415
(5.31)
417
498
532
568
622
(4.16) (4.03) (3.83) (3.76)
503 541 573 628
(4.07) (4.40) (3.89) (4.16)
511 547 574 630
(3.99) (4.46) (4.03) (3.76)
516 553 577 634
(4.02) (4.47) (4.11) (3.58)
529 571 598 658
(CHCl3)
27
(CH2Cl2)
38
(CH2Cl2)
14a
(5.23)
431
387
454
(CHCl3)
14b
(CHCl3)
32a
(4.79)
387
(4.86)
380
(4.95) (4.84) (4.16) (4.19) (4.03) (4.34)
431 456 530 569 597 657
(5.01) (5.02) (4.27) (4.03) (3.98) (4.42)
436
528
566
588
(CHCl3)
(4.85)
(5.06)
(3.86) (4.45) (4.41)
Q-band, which by convention is assigned as band I,
appears at 622 nm for OEP and has a molar absorptivity
of 5800.4 Monobenzoporphyrins (1) were first prepared
over 20 years ago5 and are minor constituents of organic-
rich sediments such as oil shales and petroleum.5,6 The
Soret band for 1 is slightly shifted to 403 nm, while
Q-band I is significantly enhanced with a molar extinc-
tion coefficient of 14 500 and a λmax value of 628 nm.
Further extension of the π-system in naphthoporphyrin
27 leads to a Soret band at 415 nm and Q-band I at 630
(ꢀ ) 5750) nm. In phenanthroporphyrin 3,8 these values
are 417 and 634 nm (ꢀ ) 3800), respectively, while the
related phenanthroline structure 49 gave a Soret band
at 424 nm and a very weak Q-band I at 636 nm. While
some small shifts are apparent, and these are somewhat
enhanced by the addition of two or more fused aromatic
ring systems,8,10-12 the overall effects are minimal, sug-
gesting that benzenoid ring fusion does not significantly
alter the porphyrin chromophore. Furthermore, there is
a trend toward diminished molar absorptivities for band
I as the size of the annelated ring system increases. On
the other hand, these extended structures do hold
promise in the development of nanomolecular systems,13
and phenanthrolinoporphyrins 4 might act as “molecular
aligator clips”.14 However, the ability to more profoundly
alter the porphyrin chromophore remains an important
goal. In this paper, we report the effects of fused
acenaphthylene and benzothiadiazole rings on the spec-
troscopic properties of annelated porphyrins. Following
on from the lackluster results for 1-4, these new systems
show remarkably large effects, which for the first time
allow the electronic structure of the porphyrin macrocycle
to be radically changed by ring fusion.
Resu lts a n d Discu ssion
Acen a p h th o[1,2-b]p or p h yr in s.15,16 The synthesis of
b-annelated porphyrins such as 1-4 generally relies on
the availability of suitable pyrrolic precursors with fused
aromatic rings. Nitroalkenes have been shown to con-
dense with isocyanoacetates in the presence of a nonnu-
cleophilic base such as DBU to give pyrrole-2-carboxy-
lates,17 and this methodology has been extended to
reactions with nitroaromatic compounds that have a
certain degree of nitroalkene character.8,9,18,19 This ap-
proach can be applied to the preparation of acenaphtho-
[1,2-c]pyrroles 5 from 1-nitroacenaphthylene 6 (Scheme
1). Hence, condensation of 6 with esters of isocyanoacetic
acid (7a -c) in the presence of 1 equiv of DBU in THF
gave the required acenaphthopyrroles 6 as stable crystal-
line compounds. The yields for the ethyl and tert-butyl
(4) Porphyrins and Metalloporphyrins; Smith, K. M., Ed.; Elsevier:
Amsterdam, 1975; pp 871-889.
(5) Clezy, P. S.; Fookes, C. J . R.; Mirza, A. H. Aust. J . Chem. 1977,
30, 1337. See also: May, D. A., J r.; Lash, T. D. J . Org. Chem. 1992,
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Academic Press: New York, 1978; Vol. 1, pp 486-552. Lash, T. D.
Energy Fuels 1993, 7, 166. Baker, E. W. J . Am. Chem. Soc. 1966, 88,
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Tome´, A. C.; Lacerdo, P. S. S.; Neves, M. G. P. M. S.; Cavaleiro, J . A.
S. Chem. Commun. 1997, 1199.
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L. T.; Senge, M. O.; Smith, K. M. J . Org. Chem. 1996, 61, 998. Bonnett,
R.; McManus, K. A. J . Chem. Soc., Perkin Trans. 1 1996, 2461.
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T. D.; Novak, B. H. Angew. Chem., Int. Ed. Engl. 1995, 34, 683.
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benzoporphyrins, see: Vincente, M. G. H.; Tome´, A. C.; Walter, A.;
Cavaleiro, J . A. S. Tetrahedron Lett. 1997, 38, 3639 and references
therein.
(13) Crossley, M. J .; Burn, P. L. J . Chem Soc., Chem. Commun.
1991, 1569. Crossley, M. J .; Prashar, J . K. Tetrahedron Lett. 1997,
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Chem. Soc., Chem. Commun. 1995, 1921.
(15) Preliminary communication: Chandrasekar, P.; Lash, T. D.
Tetrahedron Lett. 1996, 37, 4873.
(16) Results presented, in part, at the 210th National Meeting of
the American Chemical Society, Chicago, Illinois, August 1995 (Chan-
drasekar, P.; Lash, T. D. Book of Abstracts, ORGN 80); the 88th Annual
Meeting of the Illinois State Academy of Science, Eastern Illinois
University, Charleston, Illinois, October 6, 1995 (Chandrasekar, P.;
Lash, T. D. Trans. Ill. State Acad. Sci. 1995 (Supplement to Volume
88, p 52, Abstract 55)); the 211th National Meeting of the American
Chemical Society, New Orleans, Louisiana, March 28, 1996 (Chan-
drasekar, P.; Lash, T. D. Book of Abstracts, ORGN 476).
(17) Barton, D. H. R.; Zard, S. Z. J . Chem. Soc., Chem. Commun.
1985, 1098. Barton, D. H. R.; Kervagoret, J .; Zard, S. Z. Tetrahedron
1990, 46, 7587.
(18) (a) Lash, T. D.; Novak, B. H.; Lin, Y. Tetrahedron Lett. 1994,
35, 2493. (b) Lash, T. D.; Wijesinghe, C.; Osuma, A. T.; Patel, J . R.
Tetrahedron Lett. 1997, 38, 2031.
(19) (a) Ono, N.; Hironaga, H.; Simizu, K.; Ono, K.; Kuwano, K.;
Ogawa, T. J . Chem. Soc., Chem. Commun. 1994, 1019. (b) Ono, N.;
Hironaga, H.; Ono, K.; Kaneko, S.; Murashima, T.; Ueda, T.; Tsuka-
mura, C.; Ogawa, T. J . Chem. Soc., Perkin Trans. 1 1996, 417. (c)
Murashima, T.; Fujita, K.; Ono, K.; Ogawa, T.; Uno, H.; Ono, N. J .
Chem. Soc., Perkin Trans. 1 1996, 1403. (d) Murashima, T.; Tamai,
R.; Fujita, K.; Uno, H.; Ono, N. Tetrahedron Lett. 1996, 37, 8391. For
related studies, see: J aquinod, L.; Gros, C.; Olmstead, M. M.; Antolov-
ich, M.; Smith, K. M. Chem. Commun. 1996, 1475. Pelkey, E. T.;
Chang, L.; Gribble, G. W. Chem. Commun. 1996, 1909. Gros, C. P.;
J aquinod, L.; Khoury, R. G.; Olmstead, M. M.; Smith, K. M. J .
Porphyrins Phthalocyanines 1997, 1, 201.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8457
Sch em e 2
Sch em e 4
Sch em e 3
esters were in the range of 44-47%, although the benzyl
ester was obtained in somewhat lower yield. In the
proton NMR spectra, the acenaphthylene protons reso-
nated in the region from 7.5 to 7.8 ppm, with the
exception of the proton closest to the ester moiety, which
was further deshielded and appeared at 8.1 ppm. The
latter shift is much smaller than that observed in the
related phenanthro[9,10-c]pyrroles8 because the proximal
acenaphthylene proton is held further away from the
carbonyl unit. In the EI MS for 5a -c, the major
fragmentation pathway involves loss of ROH, and this
presumably results in the formation of the ketene radical
cation 8 (Scheme 2A).
porphyrinoid structures, and these successes prompted
us to explore this approach in the synthesis of acenaph-
tho[1,2-b]porphyrins. Treatment of ethyl ester 5a with
potassium hydroxide in refluxing ethylene glycol afforded
the unsubstituted acenaphtho[1,2-c]pyrrole 11a in good
yield (Scheme 1). This compound was a stable solid that
could be stored indefinitely. Proton and carbon-13 NMR
spectroscopy demonstrated the symmetry of the structure
and the absence of a carboxylate unit (also confirmed by
IR). EI MS showed the anticipated strong molecular ion
at m/z 191 with fragmentation primarily occurring with
loss of HCN (Scheme 2B); this mode of fragmentation was
also noted for the corresponding phenanthro[9,10-c]-
pyrrole 11b (vide supra).
Acenaphthopyrrole 11a was condensed with 2 equiv
of acetoxymethylpyrroles 9a , 9b, or 9c in refluxing acetic
acid/ethanol under nitrogen (Scheme 4). Precipitation by
pouring the reaction mixture into ice-water afforded the
related tripyrranes 12a -c in crude form. Tripyrrane 12c
was recrystallized from chloroform and fully character-
ized. However, tert-butyl esters 12a and 12b could not
Our previous syntheses of b-annelated porphyrins such
as naphthoporphyrins 27 and phenanthroporphyrins 38
had made effective use of MacDonald’s “2 + 2” condensa-
tion20 to construct the porphyrin macrocycle, and this
necessitated the preparation of suitably substituted
dipyrrylmethane intermediates. Condensation of ac-
etoxymethylpyrroles 9 with acenaphthopyrroles 5b or 5c
in the presence of p-toluenesulfonic acid in acetic acid or
Montmorillonite clay in dichloromethane21 gave the
required dipyrrylmethanes in excellent yields (Scheme
3). Deprotection of the ester moieties, followed by acid-
catalyzed condensation with dipyrrylmethanedialdehydes
under standard conditions,20 afforded low yields of por-
phyrin products. Although UV-vis spectra for these
crude products indicated that the acenaphthylene ring
system had a pronounced effect on the porphyrin chro-
mophore, these early studies were not sufficiently suc-
cessful to allow the isolation of pure acenaphthoporphy-
rins.
In other studies, our group9,22-24 and others25 have
found that a “3 + 1” variant on the MacDonald condensa-
tion provides an excellent alternative route to novel
(24) Lash, T. D. Angew. Chem., Int. Ed. Engl. 1995, 34, 2533. Lash,
T. D.; Chaney, S. T. Chem.sEur. J . 1996, 2, 944. Lash, T. D.; Chaney,
S. T. Tetrahedron Lett. 1996, 37, 8825. Lash, T. D.; Chaney, S. T.
Angew. Chem., Int. Ed. Engl. 1997, 36, 839. Lash, T. D.; Hayes, M. J .
Angew. Chem., Int. Ed. Engl. 1997, 36, 839. Hayes, M. J .; Lash, T. D.
Chem.sEur. J . 1998, 4, 508.
(25) Boudif, A.; Momenteau, M. J . Chem. Soc., Chem. Commun.
1994, 2069. Boudif, A.; Momenteau, M. J . Chem. Soc., Perkin Trans.
1 1996, 1235. See also: Sessler, J . L.; Genge, J . W.; Urbach, A.; Sanson,
P. Synlett 1996, 187. For an alternative “3 + 1” porphyrin synthesis,
see: Nguyen, L. T.; Senge, M. O.; Smith, K. M. J . Org. Chem. 1996,
61, 998.
(20) (a) Arsenault, G. P.; Bullock, E.; MacDonald, S. F. J . Am. Chem.
Soc. 1960, 82, 4384. (b) Cavaleiro, J . A. S.; Rocha Gonsalves, A. M.
d’A.; Kenner, G. W.; Smith, K. M. J . Chem. Soc., Perkin Trans. 1 1974,
1771. (c) Lash, T. D.; Catarello, J . J . Tetrahedron 1993, 49, 4159.
(21) J ackson, A. H.; Pandey, R. K.; Rao, K. R. N.; Roberts, E.
Tetrahedron Lett. 1985, 26, 793.
(22) Lash, T. D. Chem.sEur. J . 1996, 2, 1197.
(23) Lash, T. D. J . Porphyrins Phthalocyanines 1997, 1, 29.

8458 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
Sch em e 5
Figu r e 1. Partial 300 MHz proton NMR spectrum of acenaph-
thoporphyrin 14a in deuteriochloroform.
phyrin chromophore than does the larger phenanthrene
system, and this indicates that the UV-vis spectra for
annelated porphyrins can be modified to a far greater
extent than had been previously recognized. Interest-
ingly, the relative intensities for the three Soret bands
in chloroform solutions of 14b consistently gave some-
what different results than for 14a . In particular, the
longer wavelength Soret band (S1) for 14b (Figure 2) was
more intense (ꢀ ) 106 000) and the middle band (S2)
weaker (ꢀ ) 102 000), whereas S1 was considerably
weaker than S2 for 14a . At first glance, these differences
seem inexplicable as the chromophores would appear to
be the same for both structures. However, the acenaph-
thoporphyrins are likely to exist in solution as non-
equivalent tautomers A and B (Scheme 5), although
additional tautomers with adjacent NHs are also possible.
The chromophore for A may be distinctly different from
that for B (in A the acenaphthylene system is an integral
part of the 18π electron delocalization pathway, shown
in bold, whereas it is peripheral in tautomer B), and as
the observed UV-vis spectra for 14a and 14b must
consist of a superimposition of the absorbances for the
various tautomers in solution, any perturbation of the
relative populations for these species is likely to alter the
relative intensities of the various bands, particularly
those that are unique for a particular tautomer. The
presence of ester side chains on 14b presumably affects
the equilibrium, possibly via hydrogen-bonding interac-
tions. The intensity of S1 was slightly diminished in
spectra that were run in acetone, although this band
remained more intense for 14b than for 14a . Addition
of 1% TFA afforded the dications 15, which show a single
strong Soret band at 445 nm and a moderately intense
band at 625 nm. Again, these absorptions were strongly
red-shifted compared to the dications for phenanthro-
porphyrins 3.8 Acenaphthoporphyrin dications 15a and
15b gave similar spectra, which is to be expected as NH
tautomerization is no longer a possibility.
Porphyrin 14b was reacted with nickel(II), copper(II),
and zinc acetates under standard conditions to give the
corresponding metalloporphyrins 16 (Scheme 4), and
these also showed bathochromically shifted absorptions
in their UV-vis spectra (Figure 3). As is the case for
OEP4 and phenanthroporphyrins,8 the absorptions shift
to higher wavelength with increasing atomic number
across the periodic table. The nickel(II) complex showed
a Soret band at 434 nm, together with a strong Q-band
at 602 nm (compared to 412 and 578 nm, repectively, for
the nickel chelates of phenanthroporphyrins 3), whereas
these appear at 436 and 610 nm for the copper(II)
complex 16b and at 446 and 616 nm for the zinc chelate
16c (these values are 418 and 590 nm for the corre-
sponding zinc phenanthroporphyrin). Clearly, the un-
precedented modifying influence of the acenaphthylene
F igu r e 2. UV-vis spectra of acenaphthoporphyrin 14b: (A)
free base in chloroform. (B) Dication in 1% TFA/chloroform.
be recrystallized and were insufficiently stable in solution
to allow column chromatography to be performed. For
this reason, these critical intermediates were used in
crude form for porphyrin synthesis. The tert-butyl ester
protected tripyrranes were treated with TFA under
nitrogen for 10 min, diluted with dichloromethane, and
further reacted with the pyrroledialdehyde 13.23 Follow-
ing neutralization with triethylamine and oxidation with
1 equiv of DDQ, the products were purified by column
chromatography. The major porphyrin fractions were
recrystallized from chloroform/methanol to give the pure
acenaphthoporphyrins 14a and 14b in 33-36% yield.
The proton and carbon-13 NMR spectra for 14a and
14b confirmed the isomeric purity of the products and
demonstrated the presence of a plane of symmetry. The
aromatic ring current of the porphyrin macrocycle was
not significantly perturbed by the presence of the acenaph-
thylene subunit, and the proton NMR spectra (Figure 1)
showed the external meso protons at 10.0 and 10.4 ppm
(the latter being slightly deshielded by the adjacent
acenaphthylene ring), while the NHs were observed
upfield at -3.2 ppm. Similarly, the acenaphthylene
protons showed no indication of this moiety taking part
in an expanded delocalization pathway. Only the protons
nearest to the porphyrin were significantly deshielded,
appearing as a 2H doublet at 8.9 ppm, and this can be
attributed to the expected anisotropy for this positioning
relative to the aromatic macrocycle. While the NMR
spectra were unexceptional, the electronic spectra for
porphyrins 14a and 14b were truly unique (Figure 2).
The Soret band region was split into three strong bands
at 387, 431, and 454 nm in the case of 14a , followed by
a series of four Q-bands. The longest wavelength Q-band
appeared near 660 nm, compared to the comparitively
weak absorption at 634 nm in phenanthroporphyrin 3,
and perhaps more significantly, this band showed a molar
absorptivity of greater than 20 000. Clearly, the acenaph-
thylene unit interacts far more strongly with the por-

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8459
Sch em e 6
unit. In this series, the deprotection occurs in virtually
quantitative yield, most likely due to the very low
solubility of the product, which is thereby protected from
further reaction/degradation. The related diformylphenan-
thropyrrole 17b was prepared in a similar fashion
(Scheme 6). Phenanthropyrrole 11b was prepared from
the corresponding ethyl ester8 by treatment with KOH
in refluxing ethylene glycol. Subsequent formylation
afforded the monoaldehyde 18b, and following protection
as the cyanovinyl derivative, reformylation, and depro-
tection, the required dialdehyde was obtained in excellent
overall yield.
F igu r e 3. UV-vis spectra of acenaphthoporphyrin metal
chelates 16 in chloroform: (A) nickel(II) complex; (B) copper-
(II) complex; (C) zinc complex. Note that the UV-vis absorp-
tions shift to longer wavelengths from nickel to zinc across
the periodic table.
The availability of the dialdehydes 17 facilitated the
synthesis of both the opp-diacenaphthoporphyrin 20 and
the mixed acenaphthophenanthroporphyrin system 21
(Scheme 7). The bispropionate substituted tripyrrane
12b was selected in this study because it was anticipated
that the longer side chains would increase the solubility
of the resulting porphyrin products. Condensation of 12b
with 17a under the “3 + 1” conditions afforded the opp-
diacenaphthylene annelated porphyrin 20 in 50% yield.
Similarly, condensation of 12b with 17b gave the mixed
fused acenaphthylene/phenanthrene system 21 in 42%
yield. It is noteworthy that this mix and match approach
allows access to many novel arrangements of fused
aromatic ring systems around the periphery of the
porphyrin macrocycle and hence provides the opportunity
to fully probe the influence of fused aromatic rings on
the porphyrin chromophore. The diacenaphtho[1,2-b:1,2-
l]porphyrin 20 showed further bathochromic shifts to its
major UV-vis absorptions and demonstrated that the
presence of a second acenaphthylene unit had a cumula-
tive affect (Figure 4). Porphyrin 20 exhibited a split
Soret band a 443 and 470 nm, while Q-band I gave a
strong absorption at 692 nm. By contrast, the mixed
system 21 showed a single Soret band at 436 nm and a
far weaker Q-band I at 675 nm (Figure 4), further
underlining the minimal influence of fused phenanthrene
subunits on the electronic spectra of porphyrins. The
same trends were evident for the dications and the metal
chelates for these systems. The dication for 20 shows a
Soret band at 472 nm, compared to 466 nm for 21 and
448 nm in the case of monoacenaphthoporphyrin 15b.
For the Ni(II), Cu(II), and Zn chelates of 20, the Soret
bands were apparent at 440, 446, and 458 nm, respec-
ring system applies equally well for the free bases,
dications, and transition metal chelates of these anne-
lated porphyrin structures.
The magnitude of the effects induced by the presence
of a single acenaphthylene ring encouraged us to consider
the synthesis of diacenaphthoporphyrins. The “3 + 1”
method served as an ideal route for the synthesis of the
oppositely annealed diacenaphthylene system. To ac-
complish this synthesis, the diformylacenaphthopyrrole
17a was required, and this was obtained in excellent
overall yield (>80%) from the unsubstituted tetracycle
11a (Scheme 6). Vilsmeier formylation of 11a afforded
the monoaldehyde 18a , but this species proved to be
insufficiently reactive to allow further substitution. The
aldehyde was protected by reaction of ethyl cyanoacetate
with catalytic piperidine in refluxing ethanol to give
cyanovinylpyrrole 19a as bright-yellow crystals. Subse-
quent formylation and deprotection with refluxing aque-
ous sodium hydroxide gave the required dialdehyde 17a .
This strategy has been used to prepare pyrroledialde-
hydes for many years,26 but for simpler pyrrolic struc-
tures, the final step often gives modest yields due to
extensive decomposition that is caused by the harsh
conditions utilized in the deprotection of the cyanovinyl
(26) Dolphin, D.; Paine, J . B. III; Woodward, R. B. J . Org. Chem.
1976, 41, 2830. For an alternative one-step synthesis of pyrrole-2,5-
dicarboxaldehydes, see: Tardieux, C.; Bolze, F.; Gros, C. P.; Guilard,
R. Synthesis 1998, 267.

8460 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
Sch em e 8
F igu r e 4. UV-vis spectra of opp-diacenaphthoporphyrin 20
(dotted line) and mixed diannelated porphyrin 21 (solid line)
in chloroform.
Sch em e 7
NMR spectra, compared to 4.2 ppm in the monoacenaph-
thodipyrrylmethanes 10 and 3.8 ppm for analogous
dipyrrylmethanes without the fused aromatic subunits,
again demonstrating the modest deshielding influence
due to the fused acenaphthylene ring system. Saponi-
fication and decarboxylation was accomplished by treat-
ing 22 with KOH in refluxing ethylene glycol with strict
exclusion of oxygen. Initial attempts to condense the
crude intermediate 23 with dialdehydes 24 failed to give
more than trace amounts of the required porphyrin,
perhaps not surprisingly given the lack of success that
we had previously using this chemistry in the synthesis
of monoacenaphthoporphyrins. However, when the dipyr-
rylmethane precursors 23 and 24 were added dropwise
over a period of 2 h to a stirred solution of the acid
catalyst (this essentially mimics high-dilution condi-
tions27) and the porphodimethene intermediate 25 was
allowed to air oxidize in the presence of zinc acetate, the
required diacenaphtho[1,2-b:1,2-g]porphyrins 26 could be
isolated in 20-23% yield. While high-dilution conditions
are often favored in the formation of larger ring struc-
tures, these are usually eschewed in porphyrin synthesis
due to the risk of the intermediates undergoing fragmen-
tation/recombination reactions under the acid cyclization
conditions that can lead to isomer formation.28 In this
case, the NMR data showed that these porphyrins were
single isomers, although this need not necessarily always
be the case (vide supra). The triethyl-substituted por-
phyrin 26a was highly insoluble in organic solvents and
was not further investigated. However, the sparingly
soluble dibutylporphyrin 26b proved to be more ame-
tively, while the longest wavelength bands (strong) were
at 642, 650, and 656 nm. By contrast, these values were
434, 436, and 450 nm (Soret bands) and 618, 624, and
632 nm for the longer wavelength absorptions in the
corresponding chelates for porphyrin 21. The trend
toward longer wavelength absorptions from Ni(II) to Cu-
(II) to Zn complexes clearly also holds for these struc-
tures, but the “acenaphthylene effect” remains a strong
factor in the recorded UV-vis absorption maxima.
The synthesis of a porphyrin with adjacent fused
acenaphthylene rings could not be achieved by the “3 +
1” methodology, and this forced us to reconsider the
MacDonald “2 + 2” approach (Scheme 8). Condensation
of ethyl ester 5a with dimethoxymethane in acetic acid
containing catalytic p-toluenesulfonic acid at room tem-
perature for 3 days afforded the symmetrical dipyrryl-
methane 22 in 92% yield. The bridging methylene for
dipyrrylmethane 22 resonated at 4.6 ppm in the proton
(27) Burns, D. H.; Caldwell, T. M.; Burden, M. W. Tetrahedron Lett.
1993, 34, 2883.
(28) J ackson, A. H.; Lertwanawatana, W.; Pandey, R. K.; Rao, K.
R. N. J . Chem. Soc., Perkin Trans. 1 1989, 374.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8461
Sch em e 9
Sch em e 10
and tert-butyl esters, and the former was shown to
cleanly saponify and decarboxylate with KOH in ethylene
glycol at 180-190 °C to give the unsubstituted tricycle
29. As was the case for the acenaphthoporphyrins (vide
infra), the synthesis of porphyrins with fused benzothia-
diazole rings was attempted using the MacDonald con-
densation. Condensation of 28b with acetoxymethylpyr-
roles 9a or 9d in the presence of Montmorillonite clay in
dichloromethane afforded the dipyrrylmethanes 30 in
good yields (Scheme 10). In the proton NMR spectra, the
bridge CH2 was more deshielded than was the case for
acenaphthylene analogues 10, appearing as a 2H reso-
nance near 4.6 ppm. These compounds were reasonably
stable, although they quickly discolored on exposure to
air, but initial attempts to utilize them in the “2 + 2”
synthesis of thiadiazolobenzoporphyrins were unsuccess-
ful. However, the “3 + 1” methodology again proved to
be an excellent alternative. Condensation of 29 with 2
equiv of acetoxymethylpyrroles 9a -c in refluxing acetic
acid/ethanol afforded the tripyrranes 31a -c in good to
excellent yields. The diethyl ester 31c crystallized from
the reaction mixture and could be fully characterized, but
as was the case for the acenaphthylene series, the tert-
butyl esters 31a and 31b could not be recrystallized and
were used in crude form.
Treatment of 31a or 31b with TFA, followed by dilution
with dichloromethane, addition of dialdehyde 13, and
oxidation with DDQ, gave the novel thiadiazolobenzopor-
phyrins 32 in 31-42% yield. The availability of dialde-
hydes 17a and 17b also allowed the convenient synthesis
of the mixed systems 33a and 33b, again in excellent
yields, from tripyrrane 31b (47-55%) (Scheme 11). The
proton NMR spectra for 32 showed the expected porphy-
rin ring-current effects, although the meso protons were
further deshielded in TFA/CDCl3 due to protonation on
both the internal pyrrolenic nitrogens and the external
heterocycle. The meso proton adjacent to the thiadiazole
moiety was shifted slightly downfield for the free bases,
appearing near 10.2 ppm, but protonation shifted this
resonance to 12 ppm. Similar shifts were also noted for
the mixed diannelated porphyrins 33a and 33b. The
monoannelated porphyrins 32 gave very unusual UV-
vis spectra with broadened split Soret bands at 380 and
436 nm, although no strongly red-shifted Q-bands were
evident (Figure 5A). However, the presence of propionate
ester side chains did not significantly influence these
electronic spectra, in contrast to the results for acenaph-
thoporphyrins 14, although the shorter wavelength Soret
band for 33a was slightly more intense than was the case
for porphyrin 33b. The spectra in 1% TFA/CHCl3 also
showed a split Soret at 422 and 434 nm, although these
absorptions were somewhat sharper and more intense.
However, the most remarkabe spectra were obtained for
the metal chelates derived from 32a . The nickel(II)
complex showed two Soret bands of diminished intensity
at 386 and 428 nm, but more significantly, a strong
Q-band was evident at 600 nm. These values were 388,
nable for study. Proton and carbon-13 NMR spectroscopy
in TFA/CDCl3 confirmed the symmetry of the porphyrin
structure, and the former technique showed three reso-
nances for the meso protons at 10.6 (1H), 11.1 (2H), and
11.6 (1H) ppm. The downfield signal corresponds to the
meso proton between the two acenaphthylene rings; the
corresponding value for an adj-diphenanthroporphyrin
was 12.3 ppm,8 again demonstrating the greater deshield-
ing influence of the phenanthrene ring system. The
bathochromic shifts observed in the UV-vis spectra for
adj-diacenaphthoporphyrin 26b were less pronounced
than those observed for opp-diacenaphthoporphyrin 20,
and the principal Soret band appeared at 476 nm, while
Q-band I gave a moderately strong absorption maximum
at 672 nm. The UV-vis spectra for the dication and the
nickel(II) and zinc chelates (the copper complex could not
be formed under conventional conditions, probably due
to the low solubility of 26b) showed the same intermedi-
ary bathochromic shifts. Interestingly, dinaphtho- and
diphenanthroporphyrins8 showed the opposite trend,
where longer wavelength absorptions were noted for the
adjacent ring fused structures compared to the corre-
sponding opp-diannealed compounds. In a separate
study, the influence of four fused acenaphthylene rings29
was shown to have an even more pronounced effect on
the porphyrin chromophore, and this further confirms the
cumulative nature of the acenaphthylene ring-fusion
factor.
Th iadiazoloben zopor ph yr in s.30 Nitroaromatic com-
pounds are valuable precursors to c-annelated pyrroles,
although they vary considerably in reactivity (nitroalkene
character) and availability.8,9,18,19 4-Nitro-2,1,3-benzothi-
adiazole (27) reacts smoothly with isocyanoacetates 7 in
the presence of DBU in THF at high dilution to give the
thiadiazolobenzopyrroles 28 in good yields (Scheme 9),18b,19
and this chemistry allows the influence of this hetero-
cyclic system on the porphyrin chromophore to be as-
sessed. High-dilution conditions were not helpful in the
synthesis of acenaphthopyrroles or phenanthropyrroles,18
and the origin of this effect was not clear, although much
lower yields of 28 were obtained under conventional
conditions. Two examples of 28 were prepared, the ethyl
(29) Lash, T. D.; Chandrasekar, P. J . Am. Chem. Soc. 1996, 118,
8767. See also ref 19b.
(30) Results presented, in part, at the 211th National Meeting of
the American Chemical Society, New Orleans, Louisiana, March 28,
1996 (Osuma, A. T.; Lash, T. D. Book of Abstracts, ORGN 478) and
the 29th Great Lakes Regional American Chemical Society Meeting,
Normal, Illinois, May 1996 (Osuma, A. T.; Lash, T. D. Program and
Abstracts, Abstract 132).

8462 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
Sch em e 12
F igu r e 5. Electronic spectra of (A) thiadiazolobenzoporphyrin
32a in chloroform and (B) zinc chelate of 32a in chloroform.
Sch em e 11
most profound effects, with weak split Soret bands and
relatively strong bands above 600 nm. In the acenaph-
thylene series, the long-wavelength bands appeared at
636, 644, and 650 nm for the nickel(II), copper(II), and
zinc complexes, respectively, whereas these value were
618, 624, and 632 nm for the phenanthroporphyrin
chelates. The zinc complex of the mixed acenaphthylene/
thiadiazolobenzoporphyrin 33a not only showed the
greatest red shift, as would be expected, but more
significantly, the molar absorptivity for the band at 650
nm was greater than 80 000.
We were also interested in the synthesis of porphyrins
with two fused benzothiadiazole rings, but in this case,
the “3 + 1” route could not be easily applied due to the
lack of symmetry in the pyrrolic precursors (in the “3 +
1” method, one of the condensing fragments, tripyrrane
or dialdehyde, must be symmetrical or two isomeric
porphyrins will be formed). However, the MacDonald
condensation provided a possible route to the adj-dian-
nelated porphyrin 34 (Scheme 12). Acid-catalyzed con-
densation of 28a with dimethoxymethane afforded the
symmetrical dipyrrole 35 in quantitative yield. As would
be expected, the linking methylene unit afforded a highly
deshielded singlet at 5.3 ppm, indicating that the two
proximate benzothiadiazole rings induce a downfield shift
of 1.5 ppm. Cleavage of the ester moieties of 35 was
accomplished with KOH in refluxing ethylene glycol, and
the resulting unstable intermediate 36 was condensed
with diformyldipyrrylmethane 24b under modified Mac-
Donald condensation conditions. Virtually no porphyrin
product was produced in the initial studies, and we
turned to the slow addition protocol to overcome these
problems. This procedure increased the yield of product
to 7%, but the proton NMR spectrum showed additional
434, and 606 nm in the copper(II) chelate and 390, 442,
and 612 nm in the case of the zinc complex (Figure 5B).
Clearly, the same trends apply for these transition metal
chelates, but the appearance of a strong band at greater
than 600 nm was an unexpected bonus. The mixed
systems also provided insightful data. The acenaphtho
structure 33a gave a Soret band at 442 nm and a weak
Q-band I at 686 nm, whereas phenanthroporphyrin 33b
showed a Soret band at 440 nm and no significant bands
above 604 nm. The metal chelates again showed the

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8463
(II), or zinc acetate in methanol/chloroform34 or DMF.35 Melt-
ing points were determined in open capillary tubes on a
Thomas-Hoover melting point apparatus or a Mel-Temp ap-
paratus and are uncorrected. EI and FAB mass spectral
determinations were made at the Mass Spectral Laboratory,
School of Chemical Sciences, University of Illinois at Urbana-
Champaign, supported in part by a grant from the National
Institute of General Medical Sciences (GM 27029). Elemental
analyses were obtained from the School of Chemical Sciences
Microanalysis Laboratory at the University of Illinois.
E t h yl Acen a p h t h o[1,2-c]p yr r ole-1-ca r b oxyla t e (5a ).
DBU (4.582 g) was added dropwise to a solution of ethyl
isocyanoacetate (7a ) (3.42 g) and 1-nitroacenaphthylene (6.00
g) in THF (300 mL), and the resulting mixture was stirred at
room temperature overnight. The solution was diluted with
chloroform, washed with water, dried over sodium sulfate, and
evaporated under reduced pressure. The residue was chro-
matographed on a silica gel column (3 cm i.d. × 14.5 cm)
eluting with dichloromethane. A small amount of unreacted
1-nitroacenaphthylene was collected in the early fractions,
followed by a red band corresponding to the acenaphthopyr-
role. Recrystallization from carbon tetrachloride afforded the
title pyrrole (3.48 g, 44%) as pale-yellow needles, mp 182 °C.
IR (Nujol mull): ν 3305 (NH stretch), 1674 cm-1 (CdO stretch).
1H NMR (CDCl3): δ 1.54 (3H, t, J ) 7.2 Hz, 4.51 (2H, q, J )
7.2 Hz, 7.17 (1H, d, J ) 2.7 Hz), 7.49-7.65 (3H, m), 7.71 (1H,
d, J ) 8.1 Hz), 7.76 (1H, d, J ) 7.8 Hz), 8.11 (1H, d, J ) 6.9
Hz), 9.07 (1H, br s). 13C NMR (CDCl3): δ 14.82, 60.97, 115.04,
115.99, 119.75, 123.14, 125.18, 126.41, 127.80, 128.17, 130.56,
130.95, 132.59, 132.89, 133.45, 137.45, 161.67. MS (EI, 70 eV)
m/z (%): 263 (75) [M+], 217 (100) [M+ - EtOH], 189 (49), 163
(40). Anal. Calcd for C17H13NO2‚1/5H2O: C, 76.50; H, 5.06;
N, 5.25. Found: C, 76.61; H, 4.83; N, 5.19.
peaks that suggested an isomeric species 37 was present
(approximately 15%). The two benzothiadiazole units in
34 are orientated toward one another such that the lone
pair electrons on two of the nitrogen atoms point toward
one another, and this unfavorable interaction may hinder
the cyclization reaction. This would allow the intermedi-
ates a greater opportunity to undergo acidolysis reactions
and hence form isomeric species. This result provides a
clear warning that dilution techniques must be used with
great caution in porphyrin synthesis. Careful flash
chromatography allowed a small sample of pure 34 to
be isolated. The 300 MHz proton NMR spectrum in TFA/
CDCl3 confirmed the symmetry of the dithiadiazolopor-
phyrin and displayed the usually strong ring current with
the meso protons producing singlets at 10.7 (1H), 11.3
(2H), and 13.3 ppm (1H). The singlet at 13.3 ppm, which
is due to the meso proton that is sandwiched between
the two benzothiadiazole units, is unique to isomer 34,
as highly deshielded resonances of this type could not
arise in related structures (e.g., 37) where the two
heterocyclic units have different relative orientations. On
the other hand, the UV-vis spectra were unexceptional
showing a Soret band at 465 nm and Q-band I at 662
nm. For this reason, no further attempts were made to
optimize the chemistry leading to 34.
Con clu sion s
The “3 + 1” methodology provides a convenient and
high-yielding approach to the synthesis of novel porphy-
rin chromophores with fused aromatic subunits. Pyrroles
with fused acenaphthylene and benzothiadiazole rings
are easily synthesized from nitroaromatic precursors and
can be converted into tripyrranes in two additional steps.
Further acid-catalyzed condensation with pyrrole dial-
dehydes affords the novel acenaphtho- and thiadiaz-
olobenzoporphyrins 14 and 33. By selecting diformylpyr-
roles with fused aromatic rings, it is possible to mix and
match two different aromatic subunits on the antipodal
positions, and four examples are provided. Furthermore,
the more conventional MacDonald “2 + 2” condensation
allows access to porphyrins with two adjacent fused
subunits as well. The UV-vis spectra for these porphy-
rins and their metal chelates show that the porphyrin
chromophore has been profoundly altered, and this
suggests that the electronic spectra can be fine-tuned by
the addition of fused aromatic rings.
ter t-Bu tyl Acen aph th o[1,2-c]pyr r ole-1-car boxylate (5b).
1-Nitroacenaphthylene (0.500 g) was reacted with tert-butyl
isocyanoacetate (0.354 g) in the presence of DBU (0.764 g)
using the previous procedure. Recrystallization with chloroform/
hexanes afforded the title pyrrole (0.35 g, 47%) as bright-yellow
crystals, mp 198-199 °C. IR (Nujol mull): ν 3289 (NH
stretch), 1665 cm-1 (CdO stretch). 1H NMR (CDCl3): δ 1.74
(9H, s), 7.15 (1H, d, J ) 2.7 Hz), 7.51-7.76 (5H, m), 8.14 (1H,
d, J ) 6.6 Hz), 9.11 (1H, br s). 13C NMR (CDCl3): δ 28.83,
82.07, 114.48, 117.46, 119.60, 123.03, 125.05, 126.20, 127.77,
128.07, 130.48, 130.92, 132.57, 132.84, 132.99, 137.59, 161.26.
MS (EI, 70 eV) m/z (%): 291 (41) [M+], 235 (100) [M+
-
(CH3)2CdCH2], 217 (92) [M+ - t-BuOH], 189 (34), 163 (32).
Anal. Calcd for C19H17NO2: C, 78.33; H, 5.88; N, 4.81.
Found: C, 77.90; H, 5.85; N, 4.74.
Ben zyl Acen a p h th o[1,2-c]p yr r ole-1-ca r boxyla te (5c).
The previous procedure was adopted using benzyl isocyanoac-
etate (2.40 g), 1-nitroacenaphthylene (2.40 g), and DBU (2.24
g). The crude product was chromatographed on a silica column
eluting with toluene and recrystallized from carbon tetrachlo-
ride to give the benzyl ester (0.55 g, 14%) as fluffy yellow
needles, mp 182-184 °C. IR (Nujol mull): ν 3303 (NH
stretch), 1679 cm-1 (CdO stretch). 1H NMR (CDCl3): δ 5.18
(2H, s), 7.18 (1H, d, J ) 3.3 Hz), 7.38-7.50 (5H, m), 7.53 (2H,
m), 7.63 (1H, d, J ) 6.6 Hz), 7.71 (2H, m), 7.95 (1H, d, J ) 6.6
Hz), 9.01 (1H, br s). 13C NMR (CDCl3): δ 66.84, 115.25, 115.61,
119.81, 123.41, 125.24, 126.45, 127.77, 128.18, 128.78, 128.92,
129.02, 130.66, 130.91, 132.39, 132.77, 134.04, 136.41, 137.56,
161.29. MS (EI, 70 eV) m/z (%): 325 (100) [M+], 217 (26) [M+
Exp er im en ta l Section
Acenaphthylene (75% pure) was nitrated with nitryl chloride
in carbon tetrachloride as described by Iida et al.31 Ethyl, tert-
butyl, and benzyl isocyanoacetate were also prepared by
published methods.32,33,8b Acenaphthylene (75%), 4-nitro-2,1,3-
benzothiadiazole, DBU, piperidine, and ethyl cyanoacetate
were purchased from Aldrich Chemical Co. and were used
without further purification. Chromatography was performed
using grade 3 neutral alumina or 70-230 mesh silica gel.
Metalloporphyrins were prepared under standard conditions
by reacting the free-base porphyrin with nickel(II), copper-
- PhCH2OH], 189 (6.5), 163 (22). Anal. Calcd for C22H15
-
NO2: C, 81.21; H, 4.65; N, 4.30. Found: C, 81.36; H, 4.52; N,
4.30.
E t h yl Th ia d ia zolob en zo[3,4-c]p yr r ole-1-ca r b oxyla t e
(28a ). Ethyl isocyanoacetate (2.50 g) and DBU (3.36 g) were
dissolved in THF (1100 mL) in a 2000 mL round-bottom flask.
A solution of 4-nitro-2,1,3-benzothiadiazole in 800 mL of THF
(31) Iida, H.; Kajiyama, I.; Yamada, K. Nippon Kagaku Kaishi 1972,
137; Chem. Abstr. 1972, 76, 99395m.
(32) Hartman, G. D.; Weinstock, L. M. Org. Synth. 1979, 59, 183.
(33) Lash, T. D.; Bellettini, J . R.; Bastian, J . A.; Couch, K. B.
Synthesis 1994, 170. See also: Burns, D. H.; J abara, C. S.; Burden,
M. W. Synth. Commun. 1995, 25, 379.
(34) Porphyrins and Metalloporphyrins; Smith, K. M., Ed.; Elsevi-
er: 1975; p 798.
(35) Adler, A. D.; Longo, F. R.; Kampas, F.; Kim, J . J . Inorg. Nucl.
Chem. 1970, 32, 2443.

8464 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
was added, and the resulting dark mixture was allowed to stir
under reflux overnight. The solution was diluted with chlo-
roform, washed with water, dried over sodium sulfate, and
evaporated under reduced pressure. A residue was chromato-
graphed on silica gel eluting with chloroform. A reddish-brown
fraction was collected and recrystallized from methanol to
afford the title pyrrole (2.50 g 46%) as a pale-brown powder,
mp 173-174 °C. IR (Nujol mull): ν 3300 (NH stretch), 1691
cm-1 (CdO stretch). 1H NMR (CDCl3): δ 1.48 (3H, t, J ) 7.2
Hz), 4.49 (2H, q, J ) 7.1 Hz), 7.61 (1H, d, J ) 9.9 Hz), 7.96
(1H, d, J ) 2.7 Hz), 8.19 (1H, d, J ) 9.6 Hz), 10.09 (1H, br s).
13C NMR (d6-DMSO): δ 14.32, 60.20, 115.34, 115.69, 118.32,
119.18, 125.11, 125.57, 150.56, 154.09, 160.62. MS (EI, 70 eV)
m/z (%): 247 (90) [M+], 219 (8.5) [M+ - CH2dCH2], 201 (100)
[M+ - EtOH], 173 (33), 147 (14), 115 (7). Anal. Calcd for
long brown needles, mp 143 °C, dec. IR (Nujol mull): ν 3376
cm-1 (NH). 1H NMR (CDCl3): δ 7.27 (1H, s), 7.46 (1H, d, J )
9.3 Hz), 7.62 (1H, d, J ) 9.3 Hz), 7.79 (1H, s), 9.21 (1H, br s).
13C NMR (d6-DMSO): δ 114.02, 114.21, 114.27, 114.38, 121.54,
127.20, 151.58, 154.99. MS (EI, 70 eV) m/z (%): 175 (100)
[M+], 148 (22) [M+ - HCN]. Anal. Calcd for C8H5N3S: C,
54.84; H, 2.88; N, 23.98. Found: C, 54.99; H, 2.91; N, 23.88.
1-(2-Cya n o-2-eth oxyca r bon ylvin yl)a cen a p h th o[1,2-c]-
p yr r ole (19a ). DMF (1.10 g) was cooled in an ice bath, and
the internal temperature was maintained at 10-20 °C while
POCl3 (2.30 g) was added dropwise. An exothermic reaction
occurred with the formation of the Vilsmeier complex. The
ice bath was removed, and the mixture was stirred at room
temperature for 15 min. Dichloromethane (6 mL) was added
to the mixture, and the reaction temperature was lowered to
0-2 °C with the aid of a salt-ice bath. A solution of
acenaphthopyrrole 11a (0.90 g) in dichloromethane (4 mL) was
added to the stirred mixture over a period of 15 min. After
the addition was completed, the ice bath was replaced with a
hot water bath and the mixture was refluxed for 15 min. The
mixture was then cooled to 25-30 °C, a solution of sodium
acetate trihydrate (10.13 g) in water (14 mL) was added
dropwise, and the reaction mixture refluxed for an additional
15 min. The two layers were separated, and the aqueous
portion of the mixture was extracted with chloroform. The
combined organic layers were washed with saturated sodium
carbonate solution and dried over sodium sulfate, and the
solvent was removed under reduced pressure. The residue
(crude monoaldehyde) was treated with ethyl cyanoacetate
(0.923 g) and piperidine (7 drops) in absolute ethanol (34 mL),
and the resulting dark solution was refluxed for 3 h. The
solution was cooled to room temperature, and the resulting
yellow suspension was collected by suction filtration to give
the cyanovinyl derivative (1.34 g, 93%) as saffron-colored
crystals, mp 198-199 °C. An analytical sample was obtained
by recrystallization from dichloromethane/hexanes as small,
bright-yellow, fluffy needles, mp 199-200 °C. IR (Nujol
mull): ν 3403 (NH stretch), 2211 (CN stretch), 1700 cm-1 (Cd
O stretch). 1H NMR (CDCl3): δ 1.42 (3H, t, J ) 7.2 Hz), 4.38
(2H, q, J ) 7.2 Hz), 7.37 (1H, d, J ) 3.0 Hz), 7.52-7.85 (6H,
m), 8.34 (1H, s), 9.76 (1H, br s). 13C NMR (CDCl3): δ 14.40,
62.37, 92.03, 119.36, 120.32, 120.60, 120.84, 122.04, 125.96,
127.66, 128.14, 128.24, 130.90, 131.00, 131.62, 131.71, 137.16,
140.25, 141.11, 163.74. Anal. Calcd for C20H14N2O2: C, 76.42;
H, 4.49; N, 8.91. Found: C, 76.09; H, 4.32; N, 8.54.
C
11H9N3O2S: C, 53.43; H, 3.67; N, 16.99. Found: C, 53.30;
H, 3.67; N, 16.68.
ter t-Bu tyl Th ia d ia zoloben zo[3,4-c]p yr r ole-1-ca r boxy-
la te (28b). 4-Nitro-2,1,3-benzothiadiazole (0.500 g) was re-
acted with 0.389 g of tert-butyl isocyanoacetate in the presence
of DBU (0.420 g) using the previous procedure. Recrystalli-
zation from methanol afforded the title pyrrole (0.374 g, 49%)
as yellow needles, mp 200-201 °C. IR (Nujol mull): ν 3295
(NH stretch), 1680 cm-1 (CdO stretch). 1H NMR (CDCl3): δ
1.70 (9H, s), 7.60 (1H, d, J ) 9.6 Hz), 7.93 (1H, d, J ) 2.7 Hz),
8.14 (1H, d, J ) 9.6 Hz), 10.41 (1H, br s). 13C NMR
(d6-DMSO): δ 28.05, 81.02, 115.59, 116.63, 118.13, 118.72,
124.55, 125.75, 150.65, 154.11, 160.12. MS (EI, 70 eV) m/z
(%): 275 (23) [M+], 219 (100) [M+ - (CH3)2CdCH2], 201 (97)
[M+
13H13N3O2S: C, 56.71; H, 4.76; N, 15.29. Found: C, 56.74;
- t-BuOH], 173 (18), 147 (10). Anal. Calcd for
C
H, 4.80; N, 14.68.
Acen a p h t h o[1,2-c]p yr r ole (11a ). Nitrogen gas was
bubbled through a mixture of 5a (0.91 g) and potassium
hydroxide (2.00 g) in ethylene glycol (30 mL) for 10 min, and
the resulting solution was refluxed on a preheated oil bath at
195 °C under an atmosphere of nitrogen for an additional 30
min. The mixture was poured into ice-water, and the
resulting precipitate was collected by suction filtration, washed
well with water, and dried under vacuum overnight. The
precipitate was recrystallized from chloroform/methanol to give
the acenaphthopyrrole (0.54 g, 83%) as a pale-brown powder,
mp 128 °C. IR (KBr): ν 3355 cm-1 (NH). 1H NMR (CDCl3):
δ 7.01 (2H, d, J ) 2.4 Hz), 7.48 (2H, m), 7.57 (2H, d, J ) 6.6
Hz), 7.61 (2H, d, J ) 8.4 Hz), 8.13 (1H, br s). 13C NMR
(CDCl3): δ 110.94, 118.85, 124.38, 127.96, 129.23, 131.37,
134.21, 138.26. MS (EI, 70 eV) m/z (%): 191 (100) [M+], 164
(33) [M+ - HCN]. Anal. Calcd for C14H9N: C, 87.93; H, 4.74;
N 7.32. Found: C, 87.43; H, 4.59; N, 7.28.
P h en a n th r o[9,10-c]p yr r ole (11b). Nitrogen gas was
bubbled through a mixture of ethyl phenanthro[9,10-c]pyrrole-
1-carboxylate8 (0.50 g) and potassium hydroxide (1.00 g) in
ethylene glycol (15 mL) for 10 min, and the resulting solution
was refluxed on a preheated oil bath at 195 °C under an
atmosphere of nitrogen for an additional 30 min. The mixture
was poured into ice-water, and the resulting precipitate was
collected by suction filtration, washed well with water, and
dried under vacuum overnight to give 11b (0.37 g, 99%) as an
off-white powder, mp 150-151 °C. IR (KBr): ν 3415 (NH
stretch), 750 cm-1 (aromatic oop bending). 1H NMR (CDCl3):
δ 7.47 (4H, m), 7.57 (2H, d, J ) 2.7 Hz), 8.06 (2H, d, J ) 6.9
Hz), 8.47 (2H, d, J ) 8.1 Hz), 8.89 (1H, br s). 13C NMR
(CDCl3): δ 110.58, 120.09, 123.57, 123.87, 125.39, 127.23,
128.97, 129.13. MS (EI, 70 eV) m/z (%): 217 (100) [M+], 189
(23) [M+ - HCN]. Anal. Calcd for C16H11N‚1/10H2O: C, 87.72;
H, 5.15; N 6.39. Found: C, 87.60; H, 5.05; N, 6.48.
Acen a ph th o[1,2-c]pyr r ole-1-ca r boxa ld eh yde (18a ). Re-
crystallization of the crude product from chloroform/methanol
prior to protection with ethyl cyanoacetate afforded the
monoaldehyde 18a as greenish-yellow crystals, mp 215 °C, dec.
IR (Nujol mull): ν 3241 (NH stretch), 1645 cm-1 (CdO stretch).
1H NMR (CDCl3): δ 7.33 (1H, d, J ) 2.4 Hz), 7.53-7.63 (2H,
m), 7.67 (1H, d, J ) 6.6 Hz), 7.74 (1H, d, 8.1 Hz), 7.82 (1H, d,
J ) 8.4 Hz), 7.92 (1H, d, J ) 6.3 Hz), 9.31 (1H, br s), 10.06
(1H, s). 1H NMR (d6-DMSO/CDCl3): δ 7.09 (1H, d, J ) 3.0
Hz), 7.28-7.39 (2H, m), 7.43 (1H, d, J ) 6.9 Hz), 7.48 (1H, d,
8.4 Hz), 7.56 (1H, d, J ) 8.4 Hz), 7.92 (1H, br d), 9.80 (1H, s),
11.31 (1H, br s). 13C NMR (d6-DMSO/CDCl3): δ 118.23,
119.60, 121.80, 124.62, 125.40, 126.27, 127.44, 129.74, 130.18,
131.62, 132.27, 136.34, 177.74. Anal. Calcd for C15H9NO‚1/
10H2O: C, 81.50; H, 4.19; N, 6.33. Found: C, 81.44; H, 4.06;
N, 6.33.
1-(2-Cya n o-2-eth oxyca r bon ylvin yl)p h en a n th r o[9,10-c]-
p yr r ole (19b). Following the procedure described for 19a ,
phenanthropyrrole 11b (0.500 g) afforded the title cyanovinyl
product (714 mg, 90%) as yellowish-brown crystals, mp 208-
209 °C. An analytical sample was obtained by recrystallization
from chloroform/ethanol as saffron-colored crystals, mp 210-
210.5 °C. IR (Nujol mull): ν 3312 (NH stretch), 2214 (CN
stretch), 1707 cm-1 (CdO stretch). 1H NMR (CDCl3): δ 1.43
(3H, t, J ) 7 Hz), 4.41 (2H, q, J ) 7 Hz), 7.57-7.65 (4H, m),
8.05 (1H, d, J ) 3.3 Hz), 8.09 (1H, m), 8.38 (1H, m), 8.53 (1H,
m), 8.62 (1H, m), 8.99 (1H, s), 10.76 (1H, br s). 13C NMR
(CDCl3): δ 14.45, 62.34, 90.20, 121.84, 122.47, 123.25, 123.49,
123.88, 124.55, 125.60, 126.96, 127.40, 127.86, 128.05, 128.15,
Th ia d ia zolob en zo[3,4-c]p yr r ole (29). Nitrogen was
bubbled through a mixture of ethyl thiadiazolobenzo[3,4-c]-
pyrrole-1-carboxylate (1.00 g) and potassium hydroxide (2.35
g) in ethylene glycol (47 mL) for 10 min, and the resulting
solution was refluxed under nitrogen for 30 min. The mixture
was poured into ice-water, extracted with chloroform, dried
over sodium sulfate, and evaporated under reduced pressure.
The resulting dark residue was recrystallized from chloroform/
petroleum ether to give the R-free pyrrole (671 mg, 95%) as

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8465
129.15, 131.99, 141.23, 164.40. Anal. Calcd for C22H16N2O2:
C, 77.63; H, 4.74; N, 8.23. Found: C, 77.45; H, 4.38; N, 8.03.
P h en an th r o[9,10-c]pyr r ole-1-car boxaldeh yde (18b). Re-
crystallization of the crude monoaldehyde from carbon tetra-
chloride afforded 18b as light-brown crystals, mp 262 °C, dec.
IR (Nujol mull): ν 3223 (NH stretch), 1626 cm-1 (CdO stretch).
1H NMR (d6-DMSO/CDCl3): δ 6.84-6.96 (4H, m), 7.51 (1H,
d, J ) 3 Hz), 7.53 (1H, m), 7.88-7.97 (2H, m), 8.43 (1H, br
m), 9.61 (1H, s), 12.38 (1H, br s). 13C NMR (d6-DMSO): δ
119.37, 119.42, 121.19, 122.10, 122.21, 122.38, 123.03, 124.68,
125.87, 126.04, 126.19, 126.30, 126.95, 129.17, 177.17. Anal.
119.41, 122.19, 123.62, 124.08, 125.79, 127.68, 127.80, 129.41,
129.80, 130.11, 131.95, 132.61, 136.25, 160.58, 161.12. Anal.
Calcd for C28H28N2O4: C, 73.68; H, 6.14; N, 6.14. Found: C,
73.44; H, 6.26; N, 5.97.
Ben zyl
3-(5-Ben zyloxyca r bon yl-3-eth yl-4-m eth yl-2-
p yr r olylm e t h yl)a ce n a p h t h o[1,2-c]p yr r ole -1-ca r b oxy-
la te (10b). Montmorillonite clay (K10) (0.55 g) was added to
a mixture of acenaphthopyrrole 5c (100 mg) and benzyl
5-acetoxymethyl-4-ethyl-3-methylpyrrole-2-carboxylate (9d)23,39
(95 mg) in 10 mL of dichloromethane, and the mixture was
vigorously stirred overnight at room temperature. The mix-
ture was then suction filtered, the clay washed several times
with hot chloroform, and the solvent removed on a rotary
evaporator. The residue was recrystallized from chloroform
to give the dipyrrole (144 mg, 82%) as a pink powder, mp 246
°C, dec. IR (Nujol mull): ν 3343, 3287 (NH stretch), 1688 (Cd
O stretch), 1640 cm-1 (CdO stretch). 1H NMR (d6-DMSO/
CDCl3): δ 0.90 (3H, t, J ) 7.3 Hz), 2.22 (3H, s), 2.49 (2H, q, J
) 7.3 Hz), 4.16 (2H, s), 5.30 (2H, s), 5.45 (2H, s), 7.29-7.44
(10H, m), 7.47-7.53 (2H, m), 7.60-7.68 (2H, m), 7.83 (2H, m),
11.14 (1H, br s), 11.53 (1H, br s). 13C NMR (d6-DMSO/
CDCl3): δ 9.37, 14.62, 16.08, 22.61, 63.79, 64.85, 113.22,
116.13, 117.96, 121.59, 122.84, 123.16, 124.74, 125.06, 125.32,
126.57, 126.79, 126.88, 127.31, 127.47, 127.62, 128.13, 129.17,
129.33, 131.21, 131.87, 135.40, 135.71, 135.92, 159.77, 160.35.
Anal. Calcd for C38H32N2O4: C, 78.60; H, 5.55; N, 4.82.
Found: C, 78.36; H, 5.52; N, 4.74.
ter t-Bu tyl 3-(5-ter t-Bu toxyca r bon yl-3-eth yl-4-m eth yl-
2-p yr r olylm eth yl)th ia d ia zoloben zo[3,4-c]p yr r ole-1-ca r -
boxyla te (30a ). Montmorillonite clay (K10) (2.58 g) was
added to a mixture of tert-butyl thiadiazolobenzo[3,4-c]pyrrole-
1-carboxylate (28) (0.50 g) and tert-butyl 5-acetoxymethyl-4-
ethyl-3-methylpyrrole-2-carboxylate (9a )38 (0.51 g) in 38 mL
of dichloromethane, and the mixture was vigorously stirred
overnight at room temperature. The mixture was then suction
filtered, and the clay was washed with dichloromethane. The
solvent was evaporated to yield a reddish oily residue, which
was recrystallized from petroleum ether to give the title
dipyrrylmethane (0.665 g, 74%) as a bright-yellow powder, mp
118-120 °C. IR (Nujol mull): ν 3523, 3232 (NH stretch), 1694
(CdO stretch), 1679 cm-1 (CdO stretch). 1H NMR (CDCl3):
δ 1.00 (3H, t, J ) 7.5 Hz), 1.51 (9H, s) 1.62 (9H, s), 2.23 (3H,
s), 2.47 (2H, q, J ) 7.3 Hz), 4.59 (2H, s), 7.53 (1H, d, J ) 9.6
Hz), 8.05 (1H, d, J ) 9.6 Hz), 9.76 (1H, br s), 10.05 (1H, br s).
13C NMR (CDCl3): δ 10.51, 15.87, 17.36, 24.28, 28.61, 80.55,
82.31, 113.86, 115.51, 119.43, 119.69, 124.50, 125.23, 125.97,
126.37, 127.47, 130.89, 151.52, 154.95, 161.34, 161.54. Anal.
Calcd for C26H32N4O4S: C, 62.88; H, 6.49; N, 11.28. Found:
C, 62.76; H, 6.54; N, 10.89.
Calcd for
Found: C, 79.70; H, 4.50; N, 5.70.
C
17H11NO‚3/5H2O: C, 79.41; H, 4.80; N, 5.47.
Acen a p h th o[1,2-c]p yr r ole-1,3-d ica r boxa ld eh yd e (17a ).
The protected formyl pyrrole 19a (1.34 g) was reformylated
by the procedure detailed above with the exception of using
more solvent (approximately 60 mL of dichloromethane). The
resulting crude 1-(2-cyano-2-ethoxycarbonylvinyl)-3-formy-
lacenaphtho[1,2-c]pyrrole, which was not purified, was re-
fluxed in 3 M aqueous sodium hydroxide (44 mL) for 30 min.
The solution was cooled to room temperature and neutralized
with dilute sulfuric acid. The resulting greenish-brown pre-
cipitate was collected by suction filtration, washed several
times with water, and dried in vacuo. The crude material (1.03
g, 89%; mp >300 °C) was very sparingly soluble in many
solvents and hence was used in subsequent reactions without
recrystallization. An analytical sample was obtained by
dissolving the crude material in DMSO and diluting the
solution with chloroform as a dark-green powder. IR (Nujol
mull): ν 3237 (NH stretch), 1659 cm-1 (CdO stretch). 1H NMR
(d6-DMSO): δ 7.69 (2H, t, J ) 7.2 Hz), 7.95 (2H, d, J ) 7.8
Hz), 8.20 (2H, d, J ) 6.6 Hz), 10.11 (2H, s). 13C NMR (d6-
DMSO): δ 123.58, 127.28, 128.22, 128.44, 130.09, 130.71,
181.97. Anal. Calcd for C16H9NO2‚1/5 H2O: C, 76.62; H, 3.75;
N, 5.59. Found: C, 76.65; H, 3.74; N, 5.58.
P h en an th r o[9,10-c]pyr r ole-1,3-dicar boxaldeh yde (17b).
Cyanovinylphenanthropyrrole 19b (600 mg) was formylated
and deprotected using the conditions described above for 17a .
The dialdehyde was obtained as a brown powder (480 mg,
quantitative; mp >300 °C, dec) and was very sparingly soluble
in many solvents. Thus, succeeding reactions were carried out
using the crude material. An analytical sample was obtained
by dissolving the crude material in DMSO and diluting the
solution with chloroform as a brown powder, mp >300 °C. IR
(Nujol mull): ν 3241 (NH stretch), 1689, 1626 cm-1 (CdO
stretch). 1H NMR (d6-DMSO): δ 7.60 (4H, m), 8.75 (2H, m),
9.72 (2H, m), 10.20 (2H, s). 13C NMR (d6-DMSO): δ 123.78,
124.40, 126.43, 127.37, 127.64, 127.74, 129.81, 130.45, 182.24.
Anal. Calcd for C18H11NO2: C, 79.11; H, 4.06; N, 5.12.
Found: C, 79.41; H, 4.45; N, 5.47.
ter t-Bu tyl 3-(5-Ben zyloxyca r bon yl-3-eth yl-4-m eth yl-2-
pyr r olylm eth yl)th iadiazoloben zo[3,4-c]pyr r ole-1-car box-
yla t e (30b ). tert-Butyl thiadiazolobenzo[3,4-c]pyrrole-1-
carboxylate (28b) (0.40 g) and benzyl 5-acetoxymethyl-4-ethyl-
3-methylpyrrole-2-carboxylate (9d )39 (0.49 g) were reacted with
2.06 g of Montmorillonite clay in 30 mL of dichloromethane
by the procedure described above. The resulting product was
recrystallized from 95% ethanol to give the title dipyrryl-
methane (0.488 g, 63%) as a white powder, mp 163-165 °C.
IR (Nujol mull): ν 3336, 3264 (NH stretch), 1681 (CdO
stretch), 1631 cm-1 (CdO stretch). 1H NMR (CDCl3): δ 0.97
(3H, t, J ) 7.7 Hz), 1.60 (9H, s), 2.28 (3H, s), 2.50 (2H, q, J )
7.5 Hz), 4.59 (2H, s), 5.23 (2H, s), 7.25-7.35 (5H, m), 7.53 (1H,
d, J ) 9.6 Hz), 8.06 (1H, d, J ) 9.6 Hz), 10.18 (1H, br s), 10.44
(1H, br s); 13C NMR (CDCl3): δ 10.68, 15.81, 17.25, 24.08,
24.55, 65.98, 82.21, 113.79, 115.58, 117.92, 119.33, 124.97,
125.37, 125.93, 127.93, 128.12, 128.69, 128.79, 129.56, 130.71,
136.46, 151.39, 154.89, 161.26, 162.35. Anal. Calcd for
Eth yl 3-(5-Eth oxyca r bon yl-3-eth yl-4-m eth yl-2-p yr r o-
lylm eth yl)a cen a p h th o[1,2-c]p yr r ole-1-ca r boxyla te (10a ).
p-Toluenesulfonic acid (0.535 g) was added to a stirred mixture
of 5a (1.00 g) and 9c36,37 (0.85 g) in glacial acetic acid (135
mL). The mixture was stirred at room temperature for 2 h,
and the solution was then poured into 250 mL of ice-water
and allowed to stand for an additional 2 h. The mixture was
extracted with chloroform, washed with 50 mL of 5% sodium
bicarbonate solution then with 50 mL of water, and dried over
sodium sulfate. The solution was evaporated under reduced
pressure, and the solid residue was recrystallized from chlo-
roform to give the dipyrrylmethane (1.218 g, 70%) as a pale-
yellow powder, mp 234-235 °C. IR (Nujol mull): ν 3345, 3288
(NH stretch), 1692 (CdO stretch), 1645 cm-1 (CdO stretch).
1H NMR (CDCl3): δ 1.07 (3H, t, J ) 7.2 Hz), 1.17 (3H, br t),
1.28 (3H, br t), 2.30 (3H, s), 2.48 (2H, q, J ) 7.5 Hz), 4.09-
4.21 (4H, m), 4.26 (2H, s), 7.31 (1H, d, J ) 7.5 Hz), 7.48 (1H,
t, J ) 7.5 Hz), 7.56 (1H, t, J ) 7.5 Hz), 7.67 (1H, d, J ) 7.8
Hz), 7.75 (1H, d, J ) 8.1 Hz), 7.93 (1H, d, J ) 6.6 Hz), 9.33
(1H, br s), 9.42 (1H, br s). 13C NMR (d6-DMSO): δ 10.02,
14.36, 14.47, 15.14, 16.56, 23.46, 58.88, 59.99, 114.03, 116.80,
C
29H30N4O4S: C, 65.64; H, 5.70; N, 10.56. Found: C, 66.08;
H, 5.95; N, 9.71.
(38) Clezy, P. S.; Crowley, R. J .; Hai, T. T. Aust. J . Chem. 1982, 35,
411.
(39) J ohnson, A. W.; Kay, I. T.; Markham, E.; Price, R.; Shaw, K.
B. J . Chem. Soc. 1959, 3416.
(36) Bullock, E.; J ohnson, A. W.; Markham, E.; Shaw, K. B. J . Chem.
Soc. 1958, 1430.
(37) Lash, T. D. Tetrahedron 1998, 54, 359.

8466 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
Bis-(3-E t h oxyca r b on yl-1-a cen a p h t h o[1,2-c]p yr r olyl)-
m eth a n e (22). A mixture of ethyl acenaphtho[1,2-c]pyrrole-
1-carboxylate (5a , 0.455 g), dimethoxymethane (0.132 g), and
p-toluenesulfonic acid (50 mg) in 30 mL of glacial acetic acid
was allowed to stir under a nitrogen atmosphere at room
temperature for 3 days. The resulting cloudy mixture was
poured into 250 mL of ice-water and allowed to stand for 2
h. The resulting precipitate was filtered and vacuum dried.
The pale-yellow powder was recrystallized with THF/hexanes
to give the diacenaphthodipyrrylmethane (0.428 g, 92%) as
yellow crystals, mp 285 °C, dec. IR (Nujol mull): ν 3163 (NH
stretch), 1681 cm-1 (CdO stretch). 1H NMR (d6-DMSO): δ
1.45 (6H, t, J ) 7 Hz), 4.43 (4H, q, J ) 7 Hz), 4.56 (2H, s),
7.08 (2H, d, J ) 6.9 Hz), 7.29 (2H, d, J ) 7.2 Hz), 7.49-7.65
(2H, m), 7.54-7.58 (2H, m), 7.71 (2H, d, J ) 8.1 Hz), 8.01 (2H,
d, J ) 6.9 Hz), 12.04 (2H, br s). 13C NMR (d6-DMSO): δ 14.47,
24.99, 60.03, 114.07, 119.23, 122.28, 124.09, 125.80, 126.47,
127.62, 127.83, 128.24, 130.05, 131.94, 132.51, 132.92, 136.13,
160.57. Anal. Calcd for C35H26N2O4: C, 78.07; H, 4.83; N,
5.20. Found: C, 77.86; H, 4.97; N, 5.14.
Bis-(3-E t h oxyca r b on yl-1-t h ia d ia zolob en zo[3,4-c]p yr -
r olyl)m eth a n e (35). A mixture of ethyl thiadiazolobenzo[3,4-
c]pyrrole-1-carboxylate (28a ) (0.50 g) was condensed with
dimethoxymethane (0.154 g) and p-toluenesulfonic acid (60 mg)
in glacial acetic acid (30 mL) under the conditions described
above. Recrystallization from chloroform/petroleum ether
(60-80°) gave the title dipyrrylmethane (0.53 g, quantitative)
as a pale-yellow powder, mp 225-227 °C. IR (Nujol mull): ν
3144 (NH stretch), 1659 cm-1 (CdO stretch). 1H NMR
(CDCl3): δ 1.29 (6H, t, J ) 7.2 Hz), 4.05 (4H, q, J ) 7.1 Hz),
5.28 (2H, s), 7.51 (2H, d, J ) 9 Hz), 8.00 (2H, d, J ) 9 Hz),
11.50 (2H, br s). 13C NMR (CDCl3): δ 14.37, 25.28, 60.97,
114.26, 114.48, 119.43, 125.88, 130.22, 151.23, 154.97, 161.66.
Anal. Calcd for C23H18N6O4S2: C, 54.53; H, 3.58; N, 16.59.
Found: C, 54.54; H, 3.66; N, 16.48.
) 7.2 Hz), 1.47 (18H, s), 2.28 (6H, s), 2.42 (4H, q, J ) 7.2 Hz),
4.10 (4H, s), 7.17 (2H, d, J ) 7.2 Hz), 7.42 (2H, t, J ) 7.8 Hz),
7.56 (2H, d, J ) 8.1 Hz), 7.75 (1H, br s), 8.80 (2H, br s).
1,3-Bis-(5-eth oxyca r bon yl-3-eth yl-4-m eth yl-2-p yr r olyl-
m eth yl)th ia d ia zoloben zo[3,4-c]p yr r ole (31c). Thiadiaz-
olobenzopyrrole 29 (0.10 g) and ethyl 5-acetoxymethyl-4-ethyl-
3-methylpyrrole-2-carboxylate (9c)36,37 (0.289 g) were taken up
in ethanol (6.5 mL) and acetic acid (0.5 mL), and the mixture
was stirred while heating under reflux overnight under a
nitrogen atmosphere. The solution was poured into ice-water
(80 mL) and allowed to stand for 3 h. The precipitate was
filtered and washed with cold ethanol to give the tripyrrane
31c (0.23 g, 72%) as a pale-brown powder, mp 242-245 °C.
IR (Nujol mull): ν 3290 (NH stretch), 1667 (CdO stretch), 1639
cm-1 (CdO stretch). 1H NMR (CDCl3): δ 0.83 (6H, br t), 0.95
(3H, t), 1.03 (3H, t), 2.19 (6H, s), 2.48 (4H, m), 3.11 (4H, br),
4.16 (2H, s), 4.60 (2H, br s), 7.24 (1H, d, J ) 9.3 Hz), 7.62 (1H,
d, J ) 9.3 Hz), 10.55 (1H, br s), 11.45 (1H, br s), 11.52 (1H, br
s). 13C NMR (CDCl3): δ 10.83, 10.88, 14.06, 15.88, 15.94,
17.17, 17.32, 22.25, 23.64, 60.14, 60.26, 111.01, 114.42, 117.87,
118.18, 122.74, 123.73, 124.60, 125.32, 125.96, 126.78, 126.87,
130.84, 131.85, 152.80, 155.94, 163.95. Anal. Calcd for
C
30H35N5O4S: C, 64.15; H, 6.28; N, 12.47. Found: C, 64.00;
H, 6.44; N, 12.47.
1,3-Bis-(5-ter t-bu toxyca r bon yl-3-(2-m eth oxyca r bon yl-
eth yl)-4-eth yl-2-p yr r olylm eth yl)th ia d ia zoloben zo[3,4-c]-
p yr r ole (31b). Prepared by the previous procedure using
thiadiazolobenzopyrrole 29 (200 mg) and acetoxymethylpyrrole
9b40 (780 mg) in ethanol (15 mL)/acetic acid (1 mL). The crude
tripyrrane was obtained as a mustard-yellow powder (769 mg,
92%), but this could not be recrystallized and hence was used
without further purification. 1H NMR (CDCl3): δ 1.48 (9H,
s), 1.54 (9H, s), 2.22 (3H, s), 2.24 (3H, s), 2.45 (4H, m), 2.78
(4H, m), 3.63 (3H, s), 3.65 (3H, s), 4.17 (2H, s), 4.44 (2H, s),
7.19 (1H, d, J ) 9.3 Hz), 7.42 (1H, d, J ) 9.3 Hz), 8.77 (1H, br
s), 9.95 (1H, br s), 10.44 (1H, br s).
Bis-1,3-(5-eth oxyca r bon yl-3-eth yl-4-m eth yl-2-p yr r olyl-
m eth yl)a cen a p h th o[1,2-c]p yr r ole (12c). Acenaphthopyr-
role 11a (0.500 g) and acetoxymethylpyrrole 9c36,37 (1.387 g)
were taken up in a mixture of ethanol (30 mL) and acetic acid
(2 mL) and heated under reflux while stirring under a nitrogen
atmosphere overnight. The solution was poured into 100 mL
of ice-water and allowed to stand for 3 h. The solution was
filtered and recrystallized from chloroform to give the tripyr-
rane 12c (1.17 g, 77.5%) as a pale-yellow amorphous powder,
mp 258-260 °C. IR (Nujol mull): ν 3314 (NH stretch) 1672
cm-1 (CdO stretch). 1H NMR (d6-DMSO): δ 0.91 (6H, t, J )
7 Hz), 1.33 (6H, t, J ) 6.8 Hz), 2.24 (6H, s), 2.42 (4H, q, J )
7 Hz), 4.09 (4H, s), 4.25 (4H, q, J ) 6.8 Hz), 7.10 (2H, d, J )
6.6 Hz), 7.36 (2H, t), 7.45 (2H, d, J ) 8.1 Hz), 10.10 (1H, br s),
10.73 (2H, br s). 13C NMR (d6-DMSO/CDCl3): δ 9.30, 13.51,
14.37, 16.03, 22.93, 58.03, 116.17, 116.55, 121.73, 122.72,
123.15, 125.05, 126.58, 129.62, 129.77, 133.38, 136.54, 160.66.
Anal. Calcd for C36H39N3O4: C, 74.87; H, 6.76; N, 7.28.
Found: C, 74.90; H, 6.87; N, 7.18.
Bis-1,3-(5-ter t-Bu toxyca r bon yl-3-(2-m eth oxyca r bon yl-
et h yl)-4-et h yl-2-p yr r olylm et h yl)a cen a p h t h o[1,2-c]p yr -
r ole (12b). Following the previous procedure, acenaphtho-
pyrrole 11a (0.30 g) was reacted with 9b40 (0.98 g). The crude
tripyrrane (1.00 g; 76.5%) was obtained as a brown precipitate
but could not be recrystallized and hence was used without
further purification. Mp 104 °C, dec. IR (Nujol mull) ν 3317
(NH stretch), 1679 cm-1 (CdO stretch). 1H NMR (CDCl3): δ
1.44 (18H, s), 2.26 (6H, s), 2.47 (4H, t, J ) 7.0 Hz), 2.78 (4H,
t, J ) 7.0 Hz), 3.53 (6H, s), 4.14 (4H, s), 7.26 (2H, m), 7.42
(2H, t, J ) 7.5 Hz), 7.57 (2H, d, J ) 8.7 Hz), 8.70 (3H, br s).
Bis-1,3-(5-ter t-bu toxyca r bon yl-3-eth yl-4-m eth yl-2-p yr -
r olylm eth yl)-th ia d ia zoloben zo[3,4-c]p yr r ole (31a ). The
previous procedure was used for the preparation of 31c using
29 (0.666 g) and 9a 38 (2.14 g) in ethanol (43 mL)/acetic acid (3
mL). The resulting tripyrrane (2.30 g, 98%) could not be
recrystallized and was used without further purification. Mp
186-195 °C. IR (Nujol mull): ν 3346, 3304 (NH stretch), 1667
cm-1 (CdO stretch). 1H NMR (CDCl3): δ 0.99 (6H, m), 1.49
(18H, s), 2.21 (3H, s), 2.23 (3H, s), 2.40 (4H, m), 4.17 (2H, s),
4.42 (2H, s), 7.21 (1H, d, J ) 9.3 Hz), 7.41 (1H, d, J ) 9.3 Hz),
8.68 (1H, br), 9.00 (1H, br), 9.64 (1H, br).
8,12,13,17-Tetr a eth yl-7,18-d im eth yla cen a p h th o[1,2-b]-
p or p h yr in (14a ). Tripyrrane 12a (100 mg) was dissolved in
TFA (2 mL) and stirred at room temperature for 10 min under
nitrogen. The mixture was diluted with dichloromethane (38
mL), followed immediately by the addition of dialdehyde 1323
(32 mg). The mixture was stirred under nitrogen for an
additional further 2 h. Then, the mixture was neutralized by
the dropwise addition of triethylamine (3.6 mL), DDQ (36 mg)
was added, and the solution was stirred for another 1 h. The
solution was then diluted with chloroform was washed with
water, and the solvent evaporated under reduced pressure. The
residue was recrystallized twice with chloroform/methanol to
give the porphyrin (32 mg, 36%) as dark-blue crystals, mp
>300 °C. When the reaction was carried out with 7 mL of
TFA and 280 mL of CH2Cl2, a yield of 30 mg (33%) was
obtained. UV-vis (CHCl3): λmax (log ꢀ) 387 (4.79), 431 (4.95),
454 (4.84), 529 (4.16), 571 (4.19), 598 (4.03), 658 nm (4.34).
UV-vis (1% TFA/CHCl3): λmax (log ꢀ) 356 (4.48), 445 (5.30),
574 (4.23), 627 nm (4.58). 1H NMR (CDCl3): δ -3.25 (2H, br
s), 1.89-1.96 (12H, 2 overlapping triplets), 3.60 (6H, s), 4.05-
4.15 (8H, m), 7.94 (2H, t), 8.04 (2H, d, J ) 8.4 Hz), 8.89 (2H,
d, J ) 6.6 Hz), 9.98 (2H, s), 10.41 (2H, s). 1H NMR (TFA/
CDCl3): δ -3.3 (4H, br s), 1.76 (6H, t, J ) 7.3 Hz), 1.84 (6H,
t, J ) 7.3 Hz), 3.69 (6H, s), 4.15 (4H, q, J ) 7.5 Hz), 4.23 (4H,
q, J ) 7.5 Hz), 8.13 (2H, t, J ) 7.5 Hz), 8.32 (2H, d, J ) 8.1
Hz), 9.14 (2H, d, J ) 6.9 Hz), 10.62 (2H, s), 11.10 (2H, s). 13C
NMR (TFA-CDCl3): δ 11.88, 16.50, 17.32, 20.05, 20.34, 98.89,
100.66, 127.18, 129.45, 131.18, 131.31, 131.52, 135.62, 136.93,
Bis-1,3-(5-ter t-Bu toxyca r bon yl-3-eth yl-4-m eth yl-2-p yr -
r olylm eth yl)a cen a p h th o[1,2-c]p yr r ole (12a ). The previous
procedure was utilized for the preparation of 12b using 11a
(0.36 g) and 9a 38 (1.11 g). The resulting tripyrrane could not
be recrystallized and hence was used in crude form. Yield:
1.15 g, 72%. Mp 106 °C, dec. IR (Nujol mull): ν 3315 (NH
stretch), 1656 cm-1 (CdO). 1H NMR (CDCl3): δ 1.01 (6H, t, J
(40) Clezy, P. S.; Liepa, A. J . Aust. J . Chem. 1970, 23, 2443.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8467
138.51, 141.98, 142.57, 143.39, 144.26, 144.68, 145.41. HRMS
(EI): calcd for C40H38N4, 574.309 65; found, 574.309 73. Anal.
Calcd for C40H38N4‚1/2H2O: C, 82.30; H, 6.73; N, 9.34. Found:
C, 82.58; H, 6.70; N, 9.34.
and DDQ (31 mg). The crude product was chromatographed
on grade 3 alumina eluting with dichloromethane. A pink
prefraction was collected, followed by a major green fraction.
The latter was recrystallized from chloroform/methanol to give
the thiadiazolobenzoporphyrin (40 mg, 44%) as long purple
needles, mp >300 °C. UV-vis (CHCl3): λmax (log ꢀ) 380 (4.85),
436 (5.12), 528 (3.93), 564 (4.49), 588 nm (4.39). UV-vis (1%
TFA/CHCl3): λmax (log ꢀ) 338 (4.36), 422 (5.37), 434 (5.39), 566
(4.27), 614 nm (4.39). 1H NMR (CDCl3): δ -4.03 (2H, br s),
1.91 (6H, t, J ) 7.2 Hz), 3.23 (2H, t, J ) 7.7 Hz), 3.37 (2H, t,
J ) 7.7 Hz), 3.65 (9H, s), 3.66 (3H, s), 4.01 (4H, q, J ) 7.5 Hz),
4.37 (2H, t, J ) 7.7 Hz), 4.45 (2H, t, J ) 7.7 Hz), 8.40 (1H, d,
J ) 8.8 Hz), 9.25 (1H, d, J ) 8.8 Hz), 9.95 (1H, s), 9.97 (1H,
s), 10.06 (1H, s), 11.16 (1H, s). 1H NMR (TFA/CDCl3): δ -3.14
(2H, br s), -2.95 (2H, br s), 1.77 (6H, t, J ) 7.5 Hz), 3.25 (2H,
t, J ) 7.4 Hz), 3.33 (2H, t, J ) 7.7 Hz), 3.72 (3H, s), 3.74 (9H,
s), 4.16 (4H, q, J ) 7.5 Hz), 4.5-4.7 (4H, m), 8.96 (1H, d, J )
9.3 Hz), 9.82 (1H, d, J ) 9.3 Hz), 10.70 (2H, s), 11.33 (1H, s),
12.01 (1H, s). 13C NMR (CDCl3/TFA): δ 12.21, 17.44, 20.07,
21.86, 21.98, 29.83, 35.67, 35.80, 53.08, 53.19, 98.50, 99.99,
100.22, 101.00, 124.74, 125.40, 125.70, 134.98, 138.19, 138.56,
140.11, 140.22, 140.66, 142.22, 142.50, 142.74, 143.25, 144.76,
144.89, 150.74, 157.16, 175.36, 175.75. HRMS (EI): calcd for
C38H38N6O4S, 674.26753; found, 674.26707. Anal. Calcd for
2,3-Dieth yl-8,17-bis-(2-m eth oxyca r bon yleth yl)-7,18-d i-
m eth yla cen a p h th o[1,2-b]p or p h yr in (14b). The procedure
for 14a was adopted using 12b (100 mg), 1323 (24 mg), DDQ
(33 mg), TFA (2 mL), and CH2Cl2 (38 mL). Recrystallization
from chloroform/methanol afforded the acenaphthoporphyrin
(31 mg, 34%) as dark-blue crystals, mp >300 °C. UV-vis
(CHCl3): λmax (log ꢀ) 387 (4.86), 431 (5.01), 456 (5.02), 530
(4.27), 569 (4.03), 597 (3.98), 657 nm (4.42). UV-vis (1% TFA/
CHCl3): λmax (log ꢀ) 358 (4.52), 447 (5.31), 575 (4.31), 625 nm
(4.54). 1H NMR (CDCl3): δ -3.31 (2H, br s), 1.92 (6H, t, J )
7.5 Hz), 3.30 (4H, t, J ) 7.5 Hz), 3.59 (6H, s), 3.68 (6H, s),
4.10 (4H, q, J ) 7.5 Hz), 4.39 (4H, t, J ) 7.5 Hz), 7.98 (2H, t),
8.07 (2H, d, J ) 7.8 Hz), 8.98 (2H, d, J ) 7.2 Hz), 9.97 (2H, s),
10.39 (2H, s). 13C NMR (TFA/CDCl3): δ 12.00, 17.21, 20.04,
21.88, 35.78, 53.08, 99.18, 101.16, 127.60, 129.55, 131.18,
131.34, 131.47, 136.22, 136.92, 139.65, 140.80, 142.00, 142.69,
142.93, 144.68, 144.89, 175.83. HRMS (EI): calcd for
C
C
44H42N4O4, 691.3284; found, 691.3282. Anal. Calcd for
44H42N4O4‚H2O: C, 74.55; H, 6.25; N, 7.90. Found: C, 73.86;
H, 5.84; N, 7.69. Nickel(II) complex (16a ). Dark-purple
crystals, mp >300 °C (chloroform/methanol). UV-vis
(CHCl3): λmax (log ꢀ) 288 (4.34), 344 (4.31), 388 (4.61), 434
(4.98), 530 (3.94), 558 (4.05), 602 nm (4.62). Copper(II)
complex (16b). Dark-purple crystals, mp >300 °C (chloroform/
methanol). UV-vis (CHCl3): λmax (log ꢀ) 288 (4.50), 416 (4.87),
436 (5.10), 540 (3.97), 562 (4.05), 610 nm (4.67). Zinc complex
(16c). Dark-purple crystals, mp >300 °C (chloroform/metha-
nol). UV-vis (CHCl3): λmax (log ꢀ) 290 (4.24), 332 (4.35), 394
(4.62), 446 (5.01), 542 (3.95), 566 (4.02), 616 nm (4.59).
8,12,13,17-Tetr a eth yl-7,18-d im eth ylth ia d ia zoloben zo-
[3,4-b]p or p h yr in (32a ). Tripyrrane 31a (50 mg) was dis-
solved in TFA (1 mL) and stirred at room temperature for 10
min under nitrogen. The mixture was diluted with dichlo-
romethane (18 mL), followed by the addition of pyrroledial-
dehyde 1323 (14 mg). The mixture was stirred under nitrogen
at room temperature for an additional 2 h. The dark solution
was then neutralized by the dropwise addition of triethylamine
(1.8 mL), DDQ (18 mg) was added, and the solution stirred
for another 1 h. The solution was diluted with dichlo-
romethane and washed with water, and the solvent was
evaporated under reduced pressure. The residue was then
columned in grade 3 alumina eluting with 30% dichlo-
romethane in toluene. A greenish-purple fraction was collected
and recrystallization from chloroform/methanol giving the title
porphyrin (15 mg, 31%) as purple crystals, mp >300 °C. UV-
vis (CHCl3): λmax (log ꢀ) 380 (4.85), 436 (5.06), 528 (3.86), 566
(4.45), 588 nm (4.41). UV-vis (1% TFA/CHCl3): λmax (log ꢀ)
422 (5.34), 434 (5.37), 566 (4.25), 616 nm (4.44). 1H NMR
(TFA/CDCl3): δ -2.81 (2H, br), -2.76 (2H, br), 1.76-1.90
(12H, m), 3.68 (3H, s), 3.70 (3H, s), 4.11-4.29 (8H, m), 8.92
(1H, d, J ) 9.3 Hz), 9.69 (1H, d, J ) 9.3 Hz), 10.65 (2H, s),
11.06 (1H, s), 11.99 (1H, s). 13C NMR (TFA/CDCl3): δ 11.96,
16.46, 16.58, 17.44, 20.07, 20.28, 20.45, 97.86, 99.63, 99.85,
101.05, 124.52, 125.14, 125.65, 134.47, 137.87, 138.96, 142.16,
142.40, 142.49, 143.04, 143.22, 143.34, 144.52, 144.64, 144.93,
145.62, 150.89, 157.07. HRMS (EI): calcd for C34H34N6S,
558.25657; found, 558.25653. Anal. Calcd for C34H34N6S‚3/
5H2O: C, 71.70; H, 6.18; N, 14.75. Found: C, 71.44; H, 6.05;
N, 14.44. Nickel(II) complex. Dark-green crystals, mp >300
°C (chloroform/methanol). UV-vis (CHCl3): λmax (log ꢀ) 260
(4.46), 342 (4.40), 386 (4.82), 428 (4.84), 526 (3.86), 556 (4.07)
600 (4.64). Copper(II) complex. Dark-green crystals, mp >300
°C (chloroform/methanol). UV-vis (CHCl3): λmax (log ꢀ) 330
(4.33), 388 (4.84), 434 (4.87), 538 (3.88), 560 (4.01), 606 nm
(4.61). Zinc complex. Purple crystals, mp >300 °C (chloroform/
methanol). UV-vis (CHCl3): λmax (log ꢀ) 390 (4.84), 442 (4.84),
528 (3.88), 566 (4.01), 612 nm (4.55).
C
38H38N6O4S: C, 67.63; H, 5.68; N, 12.45; S, 4.75. Found: C,
67.25; H, 5.59; N, 12.17; S, 4.58.
7,18-B i s -(2-m e t h o x y c a r b o n y le t h y l)-8,17-d i m e t h -
yla cen a p h t h o[1,2-b]p h en a n t h r o[9,10-l]p or p h yr in (21).
Tripyrrane 12b (100 mg) was dissolved in 10 mL of TFA, and
the solution was stirred under nitrogen for 10 min. Dichlo-
romethane (390 mL) was added, followed immediately by
dialdehyde 17b (36.4 mg), and the mixture was allowed to stir
for 2 h under a nitrogen atmosphere. Triethylamine (18 mL)
was slowly added to neutralize the TFA, followed by DDQ (30
mg), and the resulting solution was stirred for an additional
1 h. The solution was washed with water and evaporated
under reduced pressure, and the residue was subjected to
chromatographic separation on a grade 3 alumina column
using dichloromethane and then chloroform as the eluent. The
product was collected as a deep-green fraction. Recrystalli-
zation from chloroform/methanol gave the title porphyrin (44
mg, 42%) as a dark-green powder, mp >300 °C. UV-vis
(CHCl3): λmax (log ꢀ) 319 (4.35), 436 (5.16), 541 (4.08), 584
(4.50), 599 (4.47), 612 (4.48), 675 nm (4.08). UV-vis (1% TFA-
CHCl3): λmax (log ꢀ) 326 (4.22), 466 (5.27), 550 (3.89), 590 (4.21),
648 nm (4.73). 1H NMR (TFA/CDCl3): δ -3.15 (1H, br s), -
2.67 (1H, br s), - 2.00 (2H, br s), 3.26 (4H, t, J ) 7 Hz), 3.72
(12H, s), 4.51 (4H, t, J ) 7 Hz), 8.11-8.21 (4H, m), 8.30-8.34
(4H, m), 9.26 (4H, t), 9.93 (2H, d, J ) 8.4 Hz), 11.19 (2H, s),
11.44 (2H, s). 13C NMR (TFA/CDCl3): δ 12.18, 21.85, 35.72,
53.12, 100.69, 100.93, 125.24, 127.45, 127.67, 129.56, 129.77,
129.93, 130.51, 131.13, 131.30, 131.50, 133.82, 136.37, 136.77,
139.24, 140.42, 142.71, 143.32, 144.43, 175.83. HRMS
(FAB): calcd for C52H40N4O4 + H, 785.3128; found, 785.3132.
Anal. Calcd for C52H40N4O4: C, 79.57; H, 5.14; N, 7.14. Found
C, 79.07; H, 5.05; N, 7.05. Nickel(II) complex. Dark-green
crystals, mp >300 °C (chloroform/methanol). UV-vis
(CHCl3): λmax (log ꢀ) 258 (4.78), 346 (4.33), 442 (5.11), 538
(3.93), 576 (4.08), 624 nm (4.79). Copper(II) complex. Dark-
green powder, mp >300 °C (chloroform/methanol). UV-vis
(CHCl3): λmax (log ꢀ) 442 (5.20), 550 (3.94), 580 (4.07), 630 nm
(4.89). Zinc complex. Dark-green powder, mp >300 °C
(chloroform/methanol). UV-vis (CHCl3): λmax (log ꢀ) 256
(4.71), 340 (4.37), 454 (5.15), 546 (3.95), 584 (4.06), 636 nm
(4.84).
7,18-Bis-(2-m et h oxyca r b on ylet h yl)-8,17-d im et h yld i-
a cen a p h th o[1,2-b:1,2-l]p or p h yr in (20). The previous pro-
cedure was repeated using tripyrrane 12b (100 mg), 17a (33
mg), DDQ (30.3 mg), TFA (7 mL), and 280 mL of dichlo-
romethane. Chromatography on neutral alumina, eluting
initially with dichloromethane and finally with 10% methanol/
chloroform, gave the product fraction. Recrystallization from
chloroform/methanol to give the porphyrin (50 mg, 50%) as a
dark-green powder, mp >300 °C. UV-vis (CHCl3): λmax (log
ꢀ) 370 (4.39), 443 (4.80), 470 (4.97), 548 (4.19), 592 (3.95), 625
2,3-Dieth yl-8,17-bis-(2-m eth oxyca r bon yleth yl)-7,18-d i-
m eth ylth ia d ia zoloben zo[3,4-b]p or p h yr in (32b). The pro-
cedure for 32a was adopted using 31b (100 mg), pyrroledial-
dehyde 1323 (24.4 mg), TFA (7 mL), dichloromethane (280 mL),

8468 J . Org. Chem., Vol. 63, No. 23, 1998
Lash et al.
(4.07), 692 nm (4.49). UV-vis (1% TFA/CHCl3): λmax (log ꢀ)
329 (4.29), 384 (4.32), 472 (5.08), 556 (4.01), 582 (4.11), 600
(4.09), 659 nm (4.63). 1H NMR (TFA/CDCl3): δ -3.16 (2H, br
s), -3.01 (2H, br s), 3.31 (4H, t, J ) 7.5 Hz), 3.74 (6H, s), 3.81
(6H, s), 4.61 (4H, t, J ) 7.5 Hz), 8.14 (4H, t), 8.35 (4H, d, J )
8.4 Hz), 9.16 (2H, d, J ) 6.9 Hz), 9.27 (2H, d, J ) 6.9 Hz),
11.04 (2H, s), 11.26 (2H, s). 13C NMR (TFA/CDCl3): δ 12.13,
21.88, 35.77, 53.12, 101.24, 101.35, 127.33, 127.70, 129.53,
129.58, 131.11, 131.25, 131.32, 131.56, 136.56, 136.83, 136.89,
140.15, 140.89, 142.68, 143.10, 144.64, 144.78, 175.80. HRMS
(FAB): calcd for C50H38N4O4 + H, 759.2971; found, 759.2968.
Anal. Calcd for C50H38N4O4‚1/2H2O: C, 78.21; H, 5.12; N, 7.30.
Found C, 78.02; H, 4.99; N, 7.16. Nickel(II) complex. Dark-
green crystals, mp >300 °C (chloroform/methanol). UV-vis
(CHCl3): λmax (log ꢀ) 270 (4.52), 346 (4.33), 440 (5.04), 528
(3.91), 642 nm (4.76). Copper(II) complex. Green crystals, mp
>300 °C (chloroform/methanol). UV-vis (CHCl3): λmax (log
ꢀ) 342 (4.31), 446 (4.74), 532 (4.05), 650 nm (4.41). Zinc
complex. Green crystals, mp >300 °C (chloroform/methanol).
UV-vis (CHCl3): λmax (log ꢀ) 282 (4.33), 352 (4.40), 458 (4.88),
656 nm (4.59).
3 alumina eluting with dichloromethane, then chloroform, and
finally 5% methanol/chloroform. A green fraction was collected
and recrystallized from chloroform/methanol to give the title
porphyrin (55 mg, 55%) as green crystals, mp >300 °C. UV-
vis (CHCl3): λmax (log ꢀ) 272 (4.24), 332 (4.57), 346 (4.55), 442
(5.29), 590 (4.51), 618 (4.77), 650 (4.02), 686 nm (3.60). UV-
vis (1% TFA/CHCl3): λmax (log ꢀ) 260 (4.37), 322 (4.34), 450
(sh, 5.20), 462 (5.31), 578 (4.16), 592 (4.23), 626 (4.01), 650
nm (4.83). 1H NMR (TFA/CDCl3): δ -2.41 (2H, br s), -2.29
(2H, br s), 3.27-3.36 (4H, m), 3.63 (3H, s), 3.68 (3H, s), 3.79
(3H, s), 3.82 (3H, s), 4.50-4.62 (4H, m), 8.12 (2H, t), 8.31 (2H,
d, J ) 8.4 Hz), 9.12 (2H, d, J ) 6.6 Hz), 8.95 (1H, d, J ) 9.3
Hz), 9.76 (1H, d, J ) 9.3 Hz), 11.10 (2H, s), 11.25 (1H, s), 11.95
(1H, s). 13C NMR (TFA/CDCl3): δ 12.15, 12.23, 21.92, 22.04,
35.69, 35.85, 53.28, 53.35, 98.63, 101.15, 102.28, 102.54,
124.83, 125.56, 125.87, 127.51, 129.61, 131.19, 131.27, 131.76,
135.24, 136.29, 136.51, 136.94, 138.94, 139.41, 140.47, 140.89,
140.97, 142.90, 143.07, 143.31, 144.02, 144.70, 144.82, 150.74,
157.20, 175.90, 176.23. HRMS (FAB): calcd for C44H34N6O4S
+
H, 743.244 05; found, 743.243 90. Anal. Calcd for
C
44H34N6O4S‚1/2H2O: C, 70.29; H, 4.69; N, 11.18; S, 4.26.
7,18-Bis-(2-m et h oxyca r b on ylet h yl)-8,17-d im et h ylt h i-
a d ia zoloben zo[3,4-b]p h en a n th r o[9,10-1]p or p h yr in (33b).
Tripyrrane 31b (100 mg) was dissolved in TFA (7 mL) and
stirred under nitrogen for 10 min. Dichloromethane (280 mL)
and phenanthro[9,10-c]pyrrole-1,3-dicarboxaldehyde (38 mg)
were added, and the mixture was allowed to stir for 2 h under
nitrogen. Triethylamine was added slowly to the reaction
mixture to neutralize the TFA. DDQ (31 mg) was then added,
and the solution was stirred for an additional 1 h. The residue
obtained after evaporation of the solution was diluted with
dichloromethane, washed with water, and evaporated under
reduced pressure. The residue was chromatographed in grade
3 alumina eluting initially with dichloromethane, then chlo-
roform and 1% methanol/chloroform. Recrystallization (twice)
from chloroform/methanol gave the title porphyrin (48 mg,
47%) as green crystals, mp >300 °C. UV-vis (CHCl3): λmax
(log ꢀ) 326 (4.40), 400 (sh, 4.78), 440 (5.06), 580 (4.52), 604 nm
(4.53). UV-vis (1% TFA/CHCl3): λmax (log ꢀ) 254 (4.63), 306
(4.27), 324 (4.26), 438 (5.08), 454 (5.07), 582 (4.24), 608 (4.03),
638 nm (4.56). 1H NMR (TFA/CDCl3): δ -2.36 (2H, br s),
-1.66 (2H, br s), 3.15-3.4 (4H, m), 3.66 (3H, s), 3.68 (3H, s),
3.72 (3H, s), 3.74 (3H, s), 4.48 (2H, t), 4.55 (2H, t), 8.18 (2H,
t), 8.33 (2H, t), 8.95 (1H, d, J ) 9 Hz), 9.27 (2H, d, J ) 8.4
Hz), 9.75 (1H, d, J ) 9 Hz), 9.93 (2H, d, 7.8 Hz), 11.23 (1H, s),
11.45 (2H, s), 11.87 (1H, s). 13C NMR (TFA/CDCl3): δ 12.24,
21.87, 35.62, 35.75, 53.09, 98.31, 100.76, 101.48, 101.74,
124.71, 125.25, 127.36, 127.53, 129.83, 129.96, 130.41, 130.46,
133.81, 134.90, 138.50, 138.82, 138.92, 139.06, 139.66, 139.87,
140.28, 143.07, 143.23, 143.33, 144.11, 150.74, 157.23, 175.19,
175.67. HRMS (FAB): calcd for C46H36N6O4S + H, 769.259 70;
found, 769.260 10. Anal. Calcd for C46H36N6O4S‚1/2H2O: C,
71.02; H, 4.79; N, 10.80; S, 4.12. Found: C, 71.05; H, 4.64; N,
10.78; S, 3.85. Nickel(II) complex. Dark-green crystals, mp
Found: C, 70.02; H, 4.56; N, 11.00; S, 4.08. Nickel(II) complex.
Dark-green powder, mp >300 °C (chloroform/methanol). UV-
vis (CHCl3): λmax (log ꢀ) 330 (4.29), 358 (4.33), 438 (4.93), 526
(3.96), 636 nm (4.69). Copper(II) complex. Dark-green crys-
tals, mp >300 °C (chloroform/methanol). UV-vis (CHCl3):
λmax (log ꢀ) 330 (4.40), 442 (5.06), 536 (4.02), 644 nm (4.72).
Zinc complex. Dark-green crystals, mp >300 °C (chloroform/
methanol). UV-vis (CHCl3): λmax (log ꢀ) 352 (4.54), 456 (5.23),
546 (3.95), 650 nm (4.91).
13,17-Dibu tyl-12,18-d im eth yld ia cen a p h th o[1,2-b:1,2-g]-
p or p h yr in (26b). A mixture of bis-(3-ethoxycarbonyl-1-
acenaphtho[1,2-c]pyrrolyl)methane (22; 0.220 g) and potassium
hydroxide (0.30 g) in ethylene glycol (30 mL) was refluxed
under nitrogen for 30 min. The reaction mixture was cooled,
diluted with chloroform, and washed with water. The organic
layer was dried over sodium sulfate and evaporated under
reduced pressure. The residue was mixed with dialdehyde
24b37 (0.140 g) in methanol (1.75 mL)/dichloromethane (50 mL)
and added dropwise over a period of 2 h to a three-necked 250
mL round-bottom flask containing p-toluenesulfonic acid (0.596
g) in methanol (1.75 mL)/dichloromethane (50 mL) under an
atmosphere of nitrogen. After the addition was complete, the
solution was allowed to stir overnight. A saturated solution
of zinc acetate in methanol (10 mL) was added, and the
resulting mixture was allowed to stir open to atmospheric
oxygen for an additional 24 h. The deep-red reaction mixture
was washed with water, evaporated under reduced pressure,
and dissolved in TFA (3 mL). The red solution was diluted
with dichloromethane, washed with water, aqueous sodium
bicarbonate solution, and water, and evaporated under reduced
pressure. The residue was washed with methanol and filtered,
and the green residue was recrystallized from chloroform/
methanol to give the adj-diacenaphthoporphyrin (55 mg, 23%)
as reddish-brown crystals, mp >300 °C. UV-vis (trace pyr-
rolidine/CHCl3): λmax (log ꢀ) 288 (4.51), 344 (4.57), 406 (4.80),
476 (5.10), 550 (4.32), 590 (4.44), 610 (4.19), 672 nm (4.34).
UV-vis (1%TFA/CHCl3): λmax (log ꢀ). 262 (4.46), 330 (4.44),
366 (4.57), 470 (5.35), 596 (4.47), 618 (4.01), 648 nm (4.60). 1H
NMR (TFA/CDCl3): δ -3.15 (4H, br s), 1.10 (6H, t, J ) 6.9
Hz), 1.70 (4H, sextet), 2.15 (4H, quintet, J ) 7.0 Hz), 3.75 (6H,
s), 4.13 (4H, t, J ) 7.5 Hz), 8.13-8.21 (4H, m), 8.35-8.39 (4H,
m), 9.18 (2H, d, J ) 6.9 Hz), 9.26 (2H, d, J ) 6.9 Hz), 10.60
(1H, s), 11.11 (2H, s), 11.61 (1H, s). 13C NMR (TFA/CDCl3):
δ 12.02, 13.75, 23.20, 26.67, 35.50, 98.90, 101.21, 103.41
127.42, 129.60, 131.29, 131.35, 131.64, 131.77, 136.01, 136.53,
137.04, 139.95, 143.39, 143.59, 144.60, 144.65, 145.06. HRMS
(EI): calcd for C50H42N4, 698.34095; found, 698.34078. Anal.
Calcd for C50H42N4‚3/4H2O: C, 84.30; H, 6.15; N, 7.86. Found:
C, 84.17; H, 5.85; N, 7.89. Nickel(II) complex. Dark-green
crystals, mp >300 °C. UV-vis (trace pyrrolidine/CHCl3): λmax
(log ꢀ) 288 (4.41), 346 (4.42), 366 (4.42), 390 (4.38), 410 (4.44),
466 (4.86), 578 (4.14), 604 (4.37), 620 nm (4.50). Zinc complex.
Green crystals, mp >300 °C. UV-vis (trace pyrrolidine/
>300
°C
(chloroform/methanol).
UV-vis
(CHCl3): λmax (log ꢀ) 256 (4.66), 350 (4.29), 420 (sh, 4.75), 434
(4.83), 540 (3.86), 578 (4.09), 618 nm (4.61). Copper(II)
complex. Dark-green crystals, mp >300 °C (chloroform/
petroleum ether). UV-vis (CHCl3): λmax (log ꢀ) 334 (4.30), 418
(4.79), 436 (4.83), 546 (3.94), 584 (4.05), 624 nm (4.58). Zinc
complex. Dark-purple flakes, mp >300 °C (chloroform/
methanol). UV-vis (CHCl3): λmax (log ꢀ) 352 (4.42),416 (4.82),
450 (5.05), 562 (3.96), 584 (3.96), 632 nm (4.77).
7,18-Bis-(2-m e t h oxyca r b on yle t h yl)-8,17-d im e t h yl-
th iadiazoloben zo[3,4-b]acen aph th o[1,2-1]por ph yr in (33a).
Tripyrrane 31b (100 mg) was dissolved in TFA (7 mL) and
stirred under nitrogen for 10 min. Dichloromethane (280 mL)
and acenaphtho[1,2-c]pyrrole-1,3-dicarboxaldehyde (33.7 mg)
were added, and the mixture was allowed to stir for 2 h under
nitrogen. Triethylamine was added slowly to the reaction
mixture to neutralize the TFA. DDQ (31 mg) was then added,
and the solution was stirred for an additional 1 h. The residue
obtained after evaporation of the solution was diluted with
dichloromethane, washed with water, and evaporated under
reduced pressure. The residue was chromatographed on grade

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 23, 1998 8469
CHCl3): λmax (log ꢀ) 296 (4.45), 342 (4.46), 374 (4.57), 414 (4.65),
468 (4.74), 496 (5.14), 596 (4.32), 646 nm (4.53).
(1H, s), 11.13 (2H, s), 13.28 (1H, s). HRMS (FAB): calcd for
C38H34N8S2 + H, 667.2428; found, 667.2426.
13,17-Dibu tyl-12,18-d im eth yld ith ia d ia zoloben zo[3,4-b:
3,4-g]p or p h yr in (34). Following the previous procedure, 34
was prepared using bis-(3-ethoxycarbonyl-1-thiadiazolobenzo-
[3,4-c]pyrrolylmethane 35 (200 mg) and 3,3′-dibutyl-4,4′-
dimethyl-2,2′-dipyrrylmethane-5,5′-dicarboxyaldehyde (24b)37
(134 mg). The residue was washed with methanol, filtered,
and recrystallized from chloroform/methanol to give the adj-
dithiadiazolobenzoporphyrin (19 mg, 7%) as green crystals, mp
>300 °C. The product was contaminated by an isomeric
species, but this could be removed by careful flash chroma-
tography eluting with 0.5% methanol/dichloromethane to give
a pure sample of porphyrin 34. UV-vis (CHCl3): λmax (log ꢀ)
367 (4.62), 400 (4.67), 465 (4.97), 549 (4.10), 583 (4.33), 662
nm (4.16). UV-vis (1% TFA/CHCl3): λmax (log ꢀ) 342 (4.40),
442 (5.32), 451 (5.28), 580 (4.24), 624 (4.45), 632 (4.46). 1H
NMR (CDCl3/TFA): δ -2.15 (4H, br), 1.07 (6H, t, J ) 7.3 Hz),
1.63 (4H, m), 2.12 (4H, m), 3.74 (6H, s), 4.14 (4H, t, J ) 7.8
Hz), 8.99 (2H, d, J ) 8.8 Hz), 9.72 (2H, d, J ) 9.8 Hz), 10.69
Ack n ow led gm en t. This material is based upon
work supported by the National Science Foundation
under Grant Nos. CHE-950063 and CHE-9732054 and
the Camille and Henry Dreyfus Scholar/Fellow Pro-
gram.
Su p p or tin g In for m a tion Ava ila ble: Copies of UV-vis
spectra for porphyrins 14, 20, 21, 26, and 32-34 and their
nickel(II), copper(II), and zinc chelates and 1H and selected
13C NMR spectra for compounds 5, 10-12, 14, 17-22, 26, and
28-35 are provided (93 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
J O9815655