148
4. Nitrogenous Compounds
107
acid. The correct site for attachment of this unit was discovered when mild
phosphorus and hydriodic acid treatment of 102 led to a substance 105
having an opened lactam ring. Structure 105 was also confirmed by synthesis.
A 1 JL
O^N^N^
NH 2
I
H
CH 2
I
CH 2 —C0 2 H
105
The remaining question, whether the second terminus of the propionyl
side chain was linked to the nitrogen atom attached to C-2 or to N-9 of the
purine system, was decided in favor of the C-2 nitrogen on the basis of yet a
further degradation. When compound 102 was successively treated with
diazomethane, alkali, and phosphorus-hydriodic acid, compound 106 was
isolated and its correct structure was established by synthesis.
N
"^LL
N
uc\
ΗΝ
N'^N
NH 2
I
Me
106
In a further communication from Professor Rapoport's laboratory (Wong
et ai, 1971b) determination of the complete structure of saxitoxin has been
reported to be 107. A remarkable feature of this unique molecule is a carbon
(shown by asterisk) that is linked to two nitrogen and two oxygen atoms. This
achievement ranks as one of the significant milestones in the chemistry of
marine natural products and brings to successful conclusion a difficult structural investigation that had its beginnings some thirty years earlier.
Occurrence of saxitoxin or substances closely related to it has been reported from two other organisms. Jackim and Gentile (1968) isolated from
zO\*/OH
Γ
/ T N H 2
I ^
V=NH 2 CI"
AH 2 N
A
Nf/
148
4. Nitrogenous Compounds
acid. The correct site for attachment of this unit was discovered when mild
phosphorus and hydriodic acid treatment of 102 led to a substance 105
having an opened lactam ring. Structure 105 was also confirmed by synthesis.
lOS
The remaining question, whether the second terminus of the propionyl
side chain was linked to the nitrogen atom attached to C-2 or to N-9 of the
purine system, was decided in favor of the C-2 nitrogen on the basis of yet a
further degradation. When compound 102 was successively treated with
diazomethane, alkali, and phosphorus-hydriodic acid, compound 106 was
isolated and its correct structure was established by synthesis.
N~N
~"T~~,)l -HC]
HN
N
N
NH 2
I
Me
106
In a further communication from Professor Rapoport's laboratory (Wong
et al., 1971 b) determination of the complete structure of saxitoxin has been
reported to be 107. A remarkable feature of this unique molecule is a carbon
(shown by asterisk) that is linked to two nitrogen and two oxygen atoms. This
achievement ranks as one of the significant Inilestones in the chemistry of
marine natural products and brings to successful concl usion a difficult structural investigation that had its beginnings some thirty years earlier.
Occurrence of saxitoxin or substances closely related to it has been reported from two other organisms. Jackim and Gentile (1968) isolated from
O~OH
~O ' . . . . NH2
N
)=NH2 CIN
H H
107
4. Nitrogenous Compounds
107
acid. The correct site for attachment of this unit was discovered when mild
phosphorus and hydriodic acid treatment of 102 led to a substance 105
having an opened lactam ring. Structure 105 was also confirmed by synthesis.
A 1 JL
O^N^N^
NH 2
I
H
CH 2
I
CH 2 —C0 2 H
105
The remaining question, whether the second terminus of the propionyl
side chain was linked to the nitrogen atom attached to C-2 or to N-9 of the
purine system, was decided in favor of the C-2 nitrogen on the basis of yet a
further degradation. When compound 102 was successively treated with
diazomethane, alkali, and phosphorus-hydriodic acid, compound 106 was
isolated and its correct structure was established by synthesis.
N
"^LL
N
uc\
ΗΝ
N'^N
NH 2
I
Me
106
In a further communication from Professor Rapoport's laboratory (Wong
et ai, 1971b) determination of the complete structure of saxitoxin has been
reported to be 107. A remarkable feature of this unique molecule is a carbon
(shown by asterisk) that is linked to two nitrogen and two oxygen atoms. This
achievement ranks as one of the significant milestones in the chemistry of
marine natural products and brings to successful conclusion a difficult structural investigation that had its beginnings some thirty years earlier.
Occurrence of saxitoxin or substances closely related to it has been reported from two other organisms. Jackim and Gentile (1968) isolated from
zO\*/OH
Γ
/ T N H 2
I ^
V=NH 2 CI"
AH 2 N
A
Nf/
148
4. Nitrogenous Compounds
acid. The correct site for attachment of this unit was discovered when mild
phosphorus and hydriodic acid treatment of 102 led to a substance 105
having an opened lactam ring. Structure 105 was also confirmed by synthesis.
lOS
The remaining question, whether the second terminus of the propionyl
side chain was linked to the nitrogen atom attached to C-2 or to N-9 of the
purine system, was decided in favor of the C-2 nitrogen on the basis of yet a
further degradation. When compound 102 was successively treated with
diazomethane, alkali, and phosphorus-hydriodic acid, compound 106 was
isolated and its correct structure was established by synthesis.
N~N
~"T~~,)l -HC]
HN
N
N
NH 2
I
Me
106
In a further communication from Professor Rapoport's laboratory (Wong
et al., 1971 b) determination of the complete structure of saxitoxin has been
reported to be 107. A remarkable feature of this unique molecule is a carbon
(shown by asterisk) that is linked to two nitrogen and two oxygen atoms. This
achievement ranks as one of the significant Inilestones in the chemistry of
marine natural products and brings to successful concl usion a difficult structural investigation that had its beginnings some thirty years earlier.
Occurrence of saxitoxin or substances closely related to it has been reported from two other organisms. Jackim and Gentile (1968) isolated from
O~OH
~O ' . . . . NH2
N
)=NH2 CIN
H H
107