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Metal-Free Derivatives of the Corphin Ligand System.

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slower than that of the 1-methylene analogs ( l a )
(M=ZnCl) and ( I c). Here, as in comparable cases,
rigorous exclusion of air is a prerequisite for the success
of this cycloisomerization (yield up to 89%);oxygen inhibits the photocyclization of secocorrinoid zinc complexes
very effectively['] and also affects the product (presumably by oxidation)["].
Assignment of constitution to the irradiation product ( 6 )
is based on the characteristic spectral changes (LJV/vIS,
IR, 'H-NMR, and MS) in going from the educt t o the
product, and on the significant correspondence of spectroscopic data for the product with those of known corrin
complexes of analogous structure, especially ( 2 c). When
compared with that of the educt the electronic spectrum
of (6) shows the expected hypsochromic shifts, and corresponds to the spectrum of the chlorozinc-corrin complex
(2c) with respect to both position and structure of the
absorption bands["]. The IR spectrum shows an absorption in the :(OH) region["] and lacks the carbonyl band
of the educt ; the absorption pattern in the structure-sensitive chromophore stretching region between 1650 and
1480 cm-' agrees with that in the spectrum of complex
(2c)['*l. A tripletoid one-proton signal at 3.65ppm in
the 'H-NMR spectrum of (6) reveals the presence of
the tertiary CH group created by the ring closure; the
spectrum also shows an OH singlet at 3.98 ppm identified
by deuterium exchange. Finally the structural change
(5)+(6) is also reflected in the expected manner in
the mass spectra of the two compounds (cf. Scheme 2).
The configuration of the linkage between rings A and
D in (6) is assumed to be anti in analogy with the known
steric outcome of the reactions ( I ) + ( 2 ) ; the close correspondence of the UV/vIS and IR spectroscopic data of
(6) and ( 2 c ) supports this assignment. However, further
studies are needed to decide whether the light-induced
ring closure (5)-(6) is a simple oxa analog of the reaction
type (f)-(2),
not only from a constitutional, but also
from a mechanistic point of view.
Received: July 10, 1973 [Z 8R9b IE]
German version: Angew. Chem. 85,952 (1973)
[ I ] a) E Yamada, D. Miljkoaic, P. Wrhrli, B. Golding, P. Loliger, R .
Kresr, K . Muller, and A. Eschenmoser, Angew. Chem. 81. 301 (1969);
Angew. Chem. internat. Edit. 8, 343 (1969): h) A . Eschenmoser, Pure
Appl. Chem. 20, 1 (1969); Quart. Rev. Chem. SOC.24, 366 (1970).
[2] H : J . Wild, Dissertation, ETH Zurich 1972.
[3] a ) A. Eschenmoser, Pure Appl. Chem. Suppl. XXllI IUPAC Congress
Boston, Vol. 2, 69 (1971); b) R. B. Woodward, Pure Appl. Chem. 33,
145 (1973); C) W Fuhrer, P. Schneider, 19: Schilling, H.-J. Wild, H. Maag,
N . Obata, A . Holmes, J . Schreiber, and A. Eschenmoser. Chimia 26, 320
(1972).
[4] a ) G . Kloster, Dissertation ETH Zurich, 1973; b) J . Gleason, B.
Place, and A . Eschenmosrr, unpublished work; cf. [3a]; c) N. Biihler,
Dissertation ETH, Zurich, 1973.
[ S ] E. Gotschi, W Hunkrlrr, H.-J. Wild, P. Schnridrr, W Fuhrer, J .
Gleason, and A. Eschenmoser, Angew. Chern. 85, 950 (1973); Angew.
Chem. internat. Edit. 12, 910 (1973).
[6] This question was posed by E. GBrschi ( A . E.).
[ 7 ] E . Gdtschi, Dissertation, ETH Zurich 1973.
[8] Prepared from the corresponding lactam and 1.5 equiv. of P2Ss
in toluene/4-methylpyridine (20: 1); 4 h ; ca. 130 'C; yield 75 % (cf. [7]).
[9] H. Oediger and F . MBller, Angew. Chem. 79, 53 (1967); Angew.
Chem internat. Edit. 6,76 (1967).
[lo] Chlorozinc-corrin complexes are efficient sensitizers for singlet
oxygen reactions ( A . Ruttimunn, Dtsserfation, ETH Zurich. 1973).
Data of l 2 c i for comparison [4bJ: ?.,,,=261
(32500), 308 (sh,
336001,317 ( 5 5 5 0 0 ). 371 (sh, 2000). 473 (14400), 496 (14200) nm (CH30H).
O=inter alia, 1618w, 1577s. 156% 1508% 1494rn c n r ' (CHCls).
[ I21 The position and broad structure of this band indicate H-bonding
of the hydroxyl group. A hydrogen bond to the chloride ligand seems
possible in the (OH/CI)-cis-configuration.
[ll]
914
Metal-Free Derivatives of the Corphin Ligand System[**]
By Peter M . Miiller, Saleem Farooq, Bruno Hardegger,
William S. Salmond, and Albert Eschenmoser['j
Metal-free derivatives of the corrin ligand system can be
obtained from corrin complexes containing metal ions
such as those of zinc, cadmium, or magnesium that are
easily displaced by a c i d o l y d l1. However, there is still
no method of removing transition-metal ions such as those
of nickel, cobalt, palladium or platinum from their robust
complexes with the corrin ligand without destruction of
the latter. The same is true for the corresponding derivatives
of the corphin ligand systemt3],where the first member was
obtained as a palladium
We report here a
process by which metal-free derivatives of this corrinoidporphinoid structural type now become accessible['].
The complexes ( l a ) and ( I b ) can be readily prepared
by the iodoenamide-thiolacram coupling procedure (cf.
Scheme I)[']. The cyanide protecting group can be removed
in high yield from the nickel complex ( I a ) by treatment
with potassium tert-butoxide to give the precorphinoid
complex ( 2 a ) . Under carefully controlled conditions the
nickel in ( 2 a ) can be replaced by zinc through treatment
with potassium cyanide and, immediately thereafter, complexing with zinc perchlorate; the unstable zinc complex
( 2 b ) is not isolated in pure form but can be cyclized
directly to the chlorozinc-corphin complex (3 a ) by alkylation with triethyloxonium tetrafluoroborate in the presence
of ethyldiisopropylamine. A more direct sequence, that
of decyanidation + cyclization starting from the cyanideprotected zinc complex ( I b ) is also feasible, but this formally shorter route proved preparatively delicate and less
reliable['].
The precorphinoid palladium complex (2c) has been described previously in connection with the original synthesis
of the palladium-corphin complex (3 c)[']. The transcomplexation-cyclization step (2) + (3) proved just as successful with this palladium complex ( 2 c ) as with the corresponding nickel derivative; thus the chlorozinc complex
( 3 a ) can now be obtained in two ways. The two routes
differ, however, in that the old one is limited to the synthesis
of corphin derivatives of centrosymmetric structure, e.g.
( 3)i61, whereas the route involving iodoenamide-thiolactam coupling can in principle also serve for the synthesis
of corphin ligands with asymmetrical structure.
The chlorozinc-corphin complex ( 3 a ) is recovered almost
unchanged under the mild conditions that suffice to
decomplex the corresponding corrin complexes (trifluoroacetic acid in acetonitrile). However, acidolyticdecomplexation can be smoothly effected with concentrated hydrochloric acid at room temperature. The corphinium ion ( 4 )
can be isolated as chloride, bromide, or perchlorate in
crystalline form. The structure assigned to it is best illustrated by the proton resonance spectrum, in which four
proton types are evident as singlets in the intensity ratio
2: 5 :6: 24. On forward titration with tetramethylammonium hydroxide in methylcellosolve-water (4 : 1 w/w)
the corphinium ion ( 4 ) shows an apparent p K ~ value
s
P. M. Muller, dipl. 1ng.-Chem. ETH-Z, Dr. S Farooq, B. Hardegger,
dipl. 1ng.-Chern. ETH-Z, Dr. W. S . Salmond, and Prof Dr. A. Eschenmoser
Organisch-Chernisches
Laboratorium
der
Eidgenossischen
Technischen Hochschule
CH-8006 Zurich, Unlversitatsstrasse 6 (Switzerland)
[**I This work was supported by the Schweizerischer Nationalfonds
zur Forderung der wissenschaftlichen Forschung.
Angrw. Chem. internat. Edit.
Vol. 12 (1973) / No. I 1
( l a ) , M=Ni':
m. p. 220 "C (dec.)
275 (18700), 339 (13200), 399 (3300m. flat), 492 (10200) nm in C,H,OH
inter alia 1747m. 1628w, 1602m, 1558s. 1510%efc. c m - ' in CHCI,
0.99/1.24/1.44/2.15 (4s/each, ICH,), 1.27 (s, 2CH,), 1.49 (s. 3CH,),
2.2-2.5 (m, SH), 5.88/6 14i6.21 (3s, each 1 H ) ppm in CDCI,
inter alia 529 (6%. M' -HCI0,/5*Ni), 514 (30",,. MI-HCI0,-CH,),
502(24%, M' - HCIO, - HCN),487 (1009<, M - HC10, - HCN -CH,)
+
ca. 6 equiv. t-BuOK in t-BuOH, 1.5 h ; ca 80'C, N, (93%)
(2a), M = N i + :
m. p. 170-1 72 "C (dec )
256 (18500j, 276 (21 3001, 346 (18700), 493 (9900) n m in C,H,OH
H3C
inter aha 1746m,1628m, 1603%1550s, 1510s, etc. c m - '
1.15/1.18/1.30/1.33/1.40/1.45 (6s, each lCH,), 1.50 (s. 2CH,), 2.43/2.83
(d, J = 2 Hz)/3.14/3.34 (4CH,), 4.76p.10 (2d. J = 3 . 5 Hz, each I H ) , 5.93,'
6.25/6.33 (3%each I H) ppm in CDCI,
interalia 502(21>0,M+-HC10,/5'Ni),487(100%,
Mt-HC10,-CH,)
H3C C H 3
(2u), M
= Ni@(C1040)
(2h), M = Zn(C1)
( Z c j , M = PdeIzl
(2uj o r
(2cj
30 equiv. KCN tn CH,OH, 10 min, room temp. -* +30 equiv.
Zn(ClO,),.6H2O+(2ci worked u p + +15(C,H,),O+BF; + 5 ethyldiisopropylamine, CH,Cl,, 19 h, room temp. (33%)
c
( 3 a ) , M=Zn(CI):
m.p. ca. 260°C (dec.)
227 (13400), 248-256 (13200), 263 (13400). 294 (sh, 38000), 302 (47600),
343 (sh, 39600), 353 (482001, 384 (sh, 7100), 410 (4900). 462 (sh. 6800),
531/547 (broad double max., 9900/9700) nm in C,H,OH
infer alia 1661w, 1634111, 1611s. 1569w, 1537s. 1502s. etc. c m - ' in CHCI,
1.35 (s, b r , 8CH,), 2.88/2.92 (m, 3CH,), 5.49 (s, 2H), 5.72/5.78/6.00 ( 3 s ,
each IH) ppm in CDC1,
inter alia 526 (11 %, M'/h4Zn/JSCI), 491 (100%, M' -Clih4Zn), 490
(47%), 476 (85%. M + -CI-CH,/04Zn), 475 (46%), etc.
a) ca. 37% HCI/H,O; room temp.; 1h- ( 4 a ) (80%)
b) Work up with satd. KBr solution containing HBr-(4b)
(4a), x
(4h), X
14c), x
=
c1
= Br
= ClO,
(4r1)-(4c)
in C F 3 C O O H
( 4 b ) , X = Br :
m.p. 234°C (dec.) from CH,CI,-CbHb
295 (46100), 321 (sh, 39000), 332 (42000), 346 (38500), 381 (sh, 7000), 404
(4500). 530 (16500) nm in C , H , O H + l drop CF,COOH per 25 ml
(spectrum in CHCI, very similar)
inter alia 3300w,br., 2445w,br., 1666s, 1644m, 1616s, 1565s, 1502s, erc.
cm-'
in
CHCI,
1.37/1.47/1.48/1.50 (4% each 2CH,), 3.06/3.17/3.27 (3s, each ICH,),
5.86/5.90/6.f0/6.24/.29 ( 5 % each 1 H), 10 1 (s,br., ca. 2H) ppm in CDCI,
inter alia 429 (20%), 428 (55%. M + - HBrj, 41 3 (loo%,M
etc.
pKGCs(Ref. [7])=7.3; equiv. wt. found 513 (calc 509)
Anyuw. Chum.
(730/,j
internat. Edit. / Vffl.I 2 ( 1 9 7 3 ) 1 No. 1 1
+
- HBr-CH,),
915
(5),X=CIO,:
290 (14000, sh), 308 (35000, sh), 321 (75000, max), 332 (43600, min),
340 (51500, sh), 353 (90500, max), 375 (36600, min), 376 (36700, max),
387 (28800, min), 393 (30600, max), ca. 450 (ca. 750, flat min), ca. 500
(ca. IOOO, flat max) nm in CFJOOH
1.34/2.79/5.47 (3s, intensity ratio 6:2:1); also m at 1.6 ppm ( c n 10%
impurities) in CF,COOH
H3C' k H 3
X~/CF3C00~
(51
Scheme 1. Properties of compounds of types ( I ) , ( 2 ) , ( 3 ) , ( 4 ) , and ( 5 ) . Spectroscopic data in the following order:
h,,, (E in brackets); selected bands from the IR spectra; signals from the proton resonance spectrum (6 values referred
to G(TMS)=O ppm); selected signals from the mass spectra. Except for ( 2 b ) and ( 5 ) . all the compounds formulated
were obtained in homogeneous crystalline form and gave correct analytical values. Detailed description of the experiments can be found in [4].
of ca. 7.3,approximately comparable with that of a carboxylic acid'']. Treatment of ( 4 a ) with nickel acetate in boiling
acetonitrile gives the nickel complex ( 3 b ) , isolated as its
crystalline perchlorate; with cobalt(r1) chloride[9] in the
presence of sodium acetate in methanol at 50"C, the
dicyanocobalt(II1)-corphin complex ( 3 d ) can easily be
obtained following work up with cyanide in contact with
air[' '1.
The complexes ( 3 a ) and (3c), as well as the metal-free
corphinium ion (4), exist in trifluoroacetic acid as derivatives of the more highly symmetrical (trans-cis)4-1,5,9,13tetraaza[i6]annulene system ( 5 ) ; in trifluoroacetic acid
their proton resonance spectra are reduced to three singlets" '1 and the corresponding electronic spectra show
unambiguously the presence of a non-corrinoid chromophore in this solvent [cf. data for ( 5 ) in Scheme 11. The
signals of the vinyl and methylene protons of the doubly
positively charged tetraazaannulene system ( 5 ) are at distinctly higher field than the corresponding groups of signals
from the singly positively charged corphinium ion (4)I"I;
the interpretation of this shift as an effect of a paramagnetic
ring current['3] in the pericyclically conjugated 4n-x-system
( 5 ) constitutes specific support for the structural assignment.
New experimental findings" 41 concerning the biosynthesis
of vitamin B I 2 have caused us to lose confidence in a
hypothesis we have cherished for a number of years,
namely, that the corphin ligand system might play a role
in the biosynthesis of naturally occurring corrinoidsE2'.Fortunately, however, the compounds of type ( 5 ) merit interest
as the porphinoid representatives of the heteroanalogs
of carbocyclic annulenes['5].
Received: July 10, 1973 [Z 889 IE]
German version: Angew. Chem. 85,954 (1973)
181
~.
According to the UV spectrum, the
protonation pri ibly leads
to a mixture of peripherally deprotonated neutral products; these were
very sparingly soluble and were not further investigated.
[9] Cf. R . B. Woodward, Pure Appl. Chem. 25, 283 (1971).
[lo] The properties of the complexes ( 3 6 ) and (3d) are described
in detail in [4].
[ I I] For complete exchange of the methylene protons of the palladium
complex ( 3 c ) by deuterium in deuteriotrifluoroacetic acid see [2].
[I21 The same is true for the complexes ( 3 a ) [4] and ( 3 c ) [2] in
CFsCOOH. The system ( 5 ) is stable for at least some hours in pure
trifluoroacetic acid at room temperature; however, on addition of stronger
acids, such as sulfuric or perchloric acid, rearrangement occurs (presumably tautomerization), whose interpretation requires further investigation.
1131 J . A. Pople and K . G . Untch, J. Amer. Chem. SOC.88, 481 1 (1966);
cf. F. Sondheimer, Accounts Chem. Res. 5 , 81 (1972); J . F M . 0 t h and
.
J . - M . Gdles, Tetrahedron Lett. 1968. 6259.
[I41 C. E . Brown, J . J . Katz, and D. Shemin, Proc. Nat. Acad. Sci.
USA 69,2585 (1972); A. I. Scott, C. A. Townsend, K . Okada, M . Kajiwara,
P . J . Whirman, and R . J . Cushley, J . Amer. Chem. Sac. 94, 8267, 8269
( 1972).
[I51 A porphinoid hexaaza-analog of [I6]annulene has been prepared
by R . Schefold and J . Loliger [personal communication from R . Srheffold;
cf. J . Loliger, Dissertation, Fribourg (Switzerland) 19711.
Cyclooctadeca[cdefgIIphenanthrene ("[181Annuleno[cdefg] phenanthrene")[ J
By U t e Meissner, Bernd Meissner, and Heinz A . Staab[*]
In 3,3':6',3":6",6-triphenanthrylene (1 ) the annulene conjugation that can be formulated as (1 a)+I 6 ) is completely suppressed in favor of x-interaction within the
phenanthrene units: the 'H-NMR spectrum does not show
any diamagnetic ring current in the macrocyclic system
but is in accordance with the existence of three largely
unperturbed phenanthrene unitsc21.
-~
[I] A. Fischliand A. Eschenmoser, Angew. Chem. 79,865 (1967); Angew.
Chem. internat. Edit. 6, 866 (1967); A. Eschenmoser, Quart. Rev. Chem.
SOC.24, 366 (1970); H . 4 . Wild, Dissertation, ETH Zurich 1972.
121 A. P. Johnson, P . Wehrli, R . Fletcher, and A. Eschenmoser, Angew.
Chem. 80, 622 (1968); Angew. Chem. internat. Edit. 7, 623 (1968).
[3] A zinc(![) octaethylphenylhexahydroxycorphin derivative has been
described by H. H. Inhogen and N . Miiller (Tetrahedron Lett. 1969,
3209).
[4] Cf. P . M . Miifler, Dissertation ETH Zurich, 1973.
[ S ] E. Gotschi, W. Hunkeler, H.-J. Wild, P. Schnrider, W. Fuhrer, J.
Gleason, and A. Eschenmoser, Angew. Chem. 85, 950 (1973); Angew.
Chem. internat. Edit. 12, 910 (1973).
163 The yields of the palladium complexes denoted as (6) and 1 8 )
in [2] have meanwhile been considerably improved: (8) can be obtained
in about 6 0 % yield from the trans-precursor complex (61, and ( 6 )
can be prepared in 85% yield by light-induced isomerization of the
corresponding cis-complex ( ( 5 ) in [2]); for details see [4].
[7] Cf. W Simon, Helv. Chim. Acta 41, 1835 (1958).
916
(101
(Ib/
In connection with the problem of the perturbation of
annulenes by condensation with benzenoid systems we
became interested in cyclooctadeca[cdefg]phenanthrene
[*I Dr. U. Meissner, Dr. B. Meissner, and Prof. Dr. H. A. Staab
Institut fur Organische Chemie der Universitat
69 Heidelberg, Im Neuenheimer Feld 7 (Germany)
Angew. Chem. internat. Edit.
Vol. 12 (1973)
/ No. I 1
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