C. Naphthalene Derivatives
101
The following year Anderson and Thomson (1966) reported a synthesis
of spinochrome Ε (17) by a different route. They followed an idea of Weygand's (1942) and condensed 3,4,5,6-tetramethoxyphthalaldehyde (37) with
glyoxal (38) in the presence of potassium cyanide, a reaction that yielded
directly the tetramethyl ether 39, which after hydrogen bromide treatment led
to spinochrome Ε (17).
OMe
OMe Ο
M
E
°1FOT
C
H
O
I
H O
M
e
°Y^yV
OH
MeO^Y^CHO
CHO
MeO^^^Y^OH
OMe
3
8
OMe Ο
37
39
These successful, if often laborious, syntheses concluded a distinct phase
of the naphthoquinone pigment research. At the end of this period it appeared
that a relatively few (six) naphthoquinone derivatives accounted for what
had earlier seemed to be a confusing array of closely related compounds,
thus providing a simple solution to what had once seemed to be a complex
problem. With the exception of Gough and Sutherland (1964), who mention
a mixture of six pigments (of which they isolated one at the time), most
workers reported mixtures of three or fewer compounds. It was a distinct
suprise, then, when Moore and co-workers (1966a) examined the calcareous
portions of two sea urchin species, Echinothrix diadema and E. calamaris
and found that these animals elaborate some thirty chromatographically
distinct pigments, most of which, but not all, overlap between the two
species. The abundance of all but two of the pigments was very low, and
while Moore et al. (1966a) processed 20 kg of spines, most of the pigments
were available to them in quantities of 20 mg or less. In addition to the benzoquinone already discussed, this work led to the characterization of about a
dozen sea urchin pigments that had not previously been encountered. Since
then Gough and Sutherland (1967) have described a new juglone and Mathieson and Thomson (1971) have isolated the same juglone and two new naphthazarins as well as two unusual dimeric naphthazarins. Since much pertinent
naphthoquinone chemistry has already been detailed during the preceding
OH
Ο
OH
Ο
" "X
Ο
OH
Ο
40
41
101
The following year Anderson and Thomson (1966) reported a synthesis
of spinochrome Ε (17) by a different route. They followed an idea of Weygand's (1942) and condensed 3,4,5,6-tetramethoxyphthalaldehyde (37) with
glyoxal (38) in the presence of potassium cyanide, a reaction that yielded
directly the tetramethyl ether 39, which after hydrogen bromide treatment led
to spinochrome Ε (17).
OMe
OMe Ο
M
E
°1FOT
C
H
O
I
H O
M
e
°Y^yV
OH
MeO^Y^CHO
CHO
MeO^^^Y^OH
OMe
3
8
OMe Ο
37
39
These successful, if often laborious, syntheses concluded a distinct phase
of the naphthoquinone pigment research. At the end of this period it appeared
that a relatively few (six) naphthoquinone derivatives accounted for what
had earlier seemed to be a confusing array of closely related compounds,
thus providing a simple solution to what had once seemed to be a complex
problem. With the exception of Gough and Sutherland (1964), who mention
a mixture of six pigments (of which they isolated one at the time), most
workers reported mixtures of three or fewer compounds. It was a distinct
suprise, then, when Moore and co-workers (1966a) examined the calcareous
portions of two sea urchin species, Echinothrix diadema and E. calamaris
and found that these animals elaborate some thirty chromatographically
distinct pigments, most of which, but not all, overlap between the two
species. The abundance of all but two of the pigments was very low, and
while Moore et al. (1966a) processed 20 kg of spines, most of the pigments
were available to them in quantities of 20 mg or less. In addition to the benzoquinone already discussed, this work led to the characterization of about a
dozen sea urchin pigments that had not previously been encountered. Since
then Gough and Sutherland (1967) have described a new juglone and Mathieson and Thomson (1971) have isolated the same juglone and two new naphthazarins as well as two unusual dimeric naphthazarins. Since much pertinent
naphthoquinone chemistry has already been detailed during the preceding
OH
Ο
OH
Ο
Ο
OH
Ο
40
41