The assignment of the vis/NIR absorptions exhibited by
active GOase has been uncertain. In addition to the afore-
mentioned π → π* and charge-transfer transitions involv-
ing Tyr-272 radical and the copper ion, a recent resonance
Raman study suggested that this absorption is dominated by a
Tyr-495→Tyr-272 radical (Fig. 1) LLCT process.38 This idea
appears to be supported by the fact that binding of azide to
active GOase, which is accompanied by displacement of
Tyr-495 from the Cu, causes a threefold reduction in intensity
K]: 1H, δ 10.99 (br, 1 H, OH), 9.99 (s, CH᎐O), 7.33 (s, 1 H), 7.31
᎐
(s, 1 H, H4 ϩ H6), 2.42 (s, 3 H, SCH3) and 2.29 (s, 3 H, CH3);
13C, δ 196.3 (CH᎐O), 155.0 (C2), 133.5 (C6), 129.5 (C5), 128.7
᎐
(C4), 127.0 (C3), 120.3 (C1), 20.0 (CH3) and 13.9 (SCH3). IR
spectrum (Nujol): 1658s cmϪ1 (C᎐O).
᎐
2-Hydroxy-5-methyl-3-methylselanylbenzaldehyde
(HL3).
Method as for HL2, using dimethyl diselenide (11.4 g, 6.07 ×
10Ϫ2 mol). The product was a yellow crystalline solid. Yield 1.4
g, 50% (Found: C, 46.9; H, 4.4. Calc. for C9H10O2Se: C, 47.2; H,
4.4%), mp 85–86 ЊC. FAB mass spectrum: m/z 231, [M ϩ H]ϩ;
230, [M]ϩ; and 215, [M Ϫ CH3]ϩ. NMR spectra [(CD3)2SO, 293
of the vis/NIR band to εmax ≈ 1 000 MϪ1 cmϪ1 1,39 This reduced
.
intensity is of similar magnitude to that shown by [2]ϩ, which
does not have a phenoxide or similar π donor as apical ligand
and so cannot undergo such an LLCT process. We are currently
preparing new model compounds designed to reproduce the
complete copper()/phenoxyl/tryptophan radical architecture
in GOase, which will further address this question.
K]: 1H, δ 11.05 (br, 1 H, OH), 9.98 (s, CH᎐O), 7.38 (s, 1 H), 7.37
᎐
(s, 1 H, H4 ϩ H6), 2.30 (s, 3 H) and 2.29 (s, 3 H, CH3 ϩ SeCH3);
13C, δ 196.4 (CH᎐O), 155.5 (C2), 135.7 (C6), 130.0 (C5), 129.6
᎐
(C4), 121.5 (C3), 120.3 (C1), 19.9 (CH3) and 4.5 (SeCH3). IR
spectrum (Nujol): 1640s cmϪ1 (C᎐O).
᎐
(2-Hydroxy-5-methylbenzylidene)methylamine (HL4Me). A
MeOH (50 cm3) solution of HL1 (0.50 g, 3.68 × 10Ϫ3 mol) and
MeNH2 (4.0 cm3 of a 1.0 M solution in MeOH, 4.0 × 10Ϫ3 mol)
was left to stand at room temperature for 15 min. Evaporation
of the solution to dryness afforded a yellow oil which was
analysed without further purification. Yield 0.52 g, 95%
(Found: C, 72.5; H, 7.4; N, 9.3. Calc. for C9H11NO: C, 72.5; H,
7.4; N, 9.4%). FAB mass spectrum: m/z 150, [M ϩ H]ϩ; and
149, [M]ϩ. NMR spectra [(CD3)2SO, 293 K]: 1H, δ 13.16 (s, 1 H,
Experimental
Unless stated otherwise, all manipulations were performed in
air using commercial grade solvents. 2-Hydroxy-5-methyl-
benzaldehyde (HL1),22 K[TpPh]23 and [Cu(O2CMe)(TpPh)]25
were prepared by the literature procedures; Cu(O2CMe)2ؒH2O
(Avocado), N,NЈ-dimethyl-1,2-diaminoethane (DMEDA),
dimethyl disulfide, dimethyl diselenide, methylamine (1.0 M
solution in MeOH), phenylamine, Bun NOH (1.0 M solution in
4
MeOH) and Cu(BF4)2ؒxH2O (x ≈ 4; Aldrich) were used as
supplied.
OH), 8.47 (s, 1 H, CH᎐N), 7.19 (d, 1.9 Hz, 1 H, H6), 7.12 (dd,
᎐
J 8.4 and 1.9, 1 H, H4), 6.77 (d, J 8.4 Hz, 1 H, H3), 3.42 (s, 3 H,
NCH3) and 2.23 (s, 3 H, CH3); 13C, δ 167.0 (CH᎐N), 158.3 (C2),
᎐
Syntheses
132.8 (C6), 131.3 (C4), 126.9 (C5), 118.4 (C1), 116.2 (C3), 45.5
(NCH3) and 19.9 (CH3).
2-(2-Hydroxy-5-methylphenyl)-1,3-dimethylimidazolidine.
The compound HL1 (10.0 g, 7.35 × 10Ϫ2 mol) and DMEDA
(7.5 g, 7.35 × 10Ϫ2 mol) were stirred in a suspension of MgSO4
in absolute EtOH (250 cm3) at room temperature for 16 h. The
solution was filtered, and the filtrate evaporated to dryness to
give a yellow oil that formed a waxy solid during storage at
Ϫ30 ЊC and was analysed without further purification. Yield
14.9 g, 100% (Found: C, 69.7; H, 8.9; N, 13.8. Calc. for
C12H16N2O: C, 69.9; H, 8.8; N, 13.6%), mp ca. 15 ЊC. FAB mass
spectrum: m/z 207, [M ϩ H]ϩ; 206, [M]ϩ and 205, [M Ϫ H]ϩ.
(2-Hydroxy-5-methylbenzylidene)phenylamine (HL4Ph).
A
MeOH (50 cm3) solution of HL1 (0.50 g, 3.68 × 10Ϫ3 mol) and
PhNH2 (0.34 g, 3.68 × 10Ϫ3 mol) was refluxed for 15 min.
Evaporation of the solution to dryness afforded an orange oil
which solidified upon trituration with Et2O. Yield 0.61 g, 78%
(Found: C, 79.6; H, 6.2; N, 6.7. Calc. for C14H13NO: C, 79.6; H,
6.2; N, 6.6%), mp 71–73 ЊC. FAB mass spectrum: m/z 212,
[M ϩ H]ϩ; 211, [M]ϩ; 210, [M Ϫ H]ϩ; 195, [M Ϫ CH3 Ϫ H]ϩ;
1
134, [M Ϫ C H ]ϩ; and 104, [C H N᎐CH]ϩ. NMR spectra
NMR spectra [(CD3)2SO, 293 K]: H, δ 11.0 (v br, 1 H, OH),
᎐
6
5
6
5
6.60 (dd, 8.2 and 2.1 Hz, 1 H, H4), 6.83 (d, J 2.1, 1 H, H6), 6.60
(d, J 8.2 Hz, 1 H, H3), 3.40 (s, 1 H, CHN2), 2.48–3.29 (m, 4 H,
NCH2), 2.20 (s, 3H, CH3) and 2.15 (s, 6 H, NCH3); 13C, δ 155.8
(C2), 131.0 (C6), 129.8 (C4), 126.3 (C5), 120.6 (C1), 115.7 (C3),
90.6 (CHN2), 51.8 (NCH2), 38.6 (NCH3) and 20.1 (CH3).
1
[(CD3)2SO, 293 K]: H, δ 12.78 (br, 1 H, OH), 8.88 (s, 1 H,
CH᎐N), 7.42 (m, 5 H, H6 ϩ NPh H2/6 ϩ H3/5), 7.31 (m, 1 H,
᎐
NPh H4), 7.22 (dd, J 8.4 and 1.8, 1 H, H4), 6.87 (d, J 8.4 Hz,
1 H, H3) and 2.26 (s, 3 H, CH3); 13C, δ 164.1 (CH᎐N), 158.9
᎐
(C2), 149.1 (NPh C1), 134.8 (C6), 133.1 (C4), 130.2 (NPh C3/5),
128.4 (C5), 127.6 (NPh C4), 122.1 (NPh C2/6), 119.8 (C1), 117.2
(C3) and 20.7 (CH3).
2-Hydroxy-5-methyl-3-methylsulfanylbenzaldehyde (HL2). To
a mixture of 2-(2-hydroxy-5-methylphenyl)-1,3-dimethylimid-
azolidine (2.5 g, 1.21 × 10Ϫ2 mol) and TMEDA (5.6 g,
4.85 × 10Ϫ2 mol) in distilled Et2O (150 cm3) at Ϫ78 ЊC under N2
was added BunLi (32.3 cm3 of a 1.5 M solution in hexanes,
4.85 × 10Ϫ2 mol). The solution was allowed to warm to room
temperature and stirred for 6 h, during which time the initial
precipitate dissolved and the solution slowly became orange.
Dimethyl disulfide (5.7 g, 6.07 × 10Ϫ2 mol) was then carefully
added (mildly exothermic), giving a yellow solution and white
precipitate which was stirred overnight. The mixture was
poured onto 2 M HCl (200 cm3) and stirred for 10 min. The
ether layer was separated, and the aqueous layer extracted 3
times with CH2Cl2. The combined organic extracts were dried
over MgSO4 and evaporated to dryness. The residue was dis-
solved in 2:1 hexanes–ethyl acetate and filtered through a silica
plug. Evaporation of the solvent yielded a pungent oily yellow
solid, which formed a yellow crystalline material upon washing
with the minimum volume of hexanes. Yield 1.6 g, 73% (Found:
C, 59.2; H, 5.5. Calc. for C9H10O2S: C, 59.3; H, 5.5%), mp 80–
81 ЊC. FAB mass spectrum: m/z 183, [M ϩ H]ϩ; 182, [M]ϩ; 181,
[M Ϫ H]ϩ; and 167, [M Ϫ CH3]ϩ. NMR spectra [(CD3)2SO, 293
(2-Hydroxy-5-methyl-3-methylsulfanylbenzylidene)methyl-
amine (HL5Me). Method as for HL4Me, using HL2 (0.67 g,
3.68 × 10Ϫ3). The orange oil thus obtained was triturated with
Et2O to afford an orange solid. Yield 0.52 g, 73% (Found: C,
61.3; H, 6.6; N, 7.1. Calc. for C10H13NOS: C, 61.5; H, 6.7; N,
7.2%), mp 94–95 ЊC. FAB mass spectrum: m/z 196, [M ϩ H]ϩ;
195, [M]ϩ; 194, [M Ϫ H]ϩ; 181, [M Ϫ CH3]ϩ; and 162 [M Ϫ
1
SH]. NMR spectra [(CD3)2SO, 293 K]: H, δ 14.07 (br, 1 H,
OH), 8.43 (s, 1 H, CH᎐N), 7.00 (s, 1 H), 6.95 (s, 1 H, Ph
᎐
H4 ϩ H6), 3.49 (s, 3 H, NCH3), 2.36 (s, 3 H, SCH3) and 2.23 (s,
3 H, CH3); 13C, δ 167.1 (CH᎐N), 158.4 (C2), 129.1 (C6), 127.6
᎐
(C4), 126.5, 126.2 (C3 ϩ C5), 116.1 (C1), 43.6 (NCH3), 20.2
(CH3) and 13.6 (SCH3).
(2-Hydroxy-5-methyl-3-methylsulfanylbenzylidene)phenyl-
amine (HL5Ph). Method as for HL4Ph, using HL2 (0.67 g,
3.68 × 10Ϫ3). The product formed blood-red plates from Et2O.
Yield 0.67 g, 71% (Found: C, 69.9; H, 5.9; N, 5.4. Calc. for
C15H15NOS: C, 70.0; H, 5.9; N, 5.4%), mp 74–75 ЊC. FAB mass
spectrum: m/z 257, [M ϩ H]ϩ; 256, [M]ϩ; 242, [M Ϫ CH3]ϩ;
J. Chem. Soc., Dalton Trans., 1999, 1753–1762
1759