The new bleaching herbicidal compound N,N-diethyl-N-(2-undecynyl)amine (NDUA) is identified here as an inhibitor of lycopene cyclase and is compared with the known cyclase inhibitors N,N-diethyl-N-[2-(4-chlorophenylthio)ethyl]amine (CPTA) and N,N-diethyl-N-[2-(4-methylphenoxy)ethyl]amine (MTPA). HPLC separation of chloroplast pigments shows lycopene accumulation in NDUA treated tissue. Variation in chain length of the undecynylamine moeity of NDUA from 7 to 21 C atoms reveals an optimum of 11 to 14 C atoms for herbicidal activity. A series of seven further analogues of NDUA and CPTA reveals the structural elements necessary for inhibition of lycopene cyclase. The effect of NDUA derivatives on photosynthesis has been studied in Chlamydomonas reinhardtii. Photosynthesis is highly sensitive, particularly towards the C14 and longer chain length analogues at nanomolar concentrations. It is shown that the breakdown of photosynthesis by NDUA is due to interference with the turnover of the D1 protein of the photosystem II reaction centre that requires the continuous biosynthesis of the two reaction-centre beta-carotene moieties in the reassembly phase. The D1 protein disappearance is most marked under strong light conditions. The depletion of photosystem II occurs before total pigment bleaching. This newly recognized mechanism in herbicidal activity is also the basis for the mode of action of other lycopene cyclase inhibitors as well as phytoene desaturase inhibitors.

A series of 20 triazines (derivatives of 2-alkylamino-4-benzylam ino-6-chloro-1,3,5-triazines) and 37 triazinones (derivatives of 3-alkyl-4-amino-6-phenyl-1,2,4-triazin-5-ones) is tested for inhibitory potency in photosynthetic electron flow through photosystem II of wild type Chlamydomonas reinhardtii and of five mutants with aminoacid substitutions in the D 1 protein at valine 219, alanine 251, phenylalanine 255, serine 264, and leucine 275. The data are used for computer modelling of the possible location of the compounds within a three dimensional model of the QB-binding niche of the D 1 protein.

Decomposition of 5-Norbornene-2-diazonium Ions. Derivatives of Bicyclo[3.l.l]hept-2-enePhotolysis of 5-norbornen-2-one tosylhydrazone (4) in aqueous sodium hydroxide afforded 4% of 3-norpinen-2-01 (3) in addition to 5-norbornen-2-01 (5, 10%) and nortricyclanol(6,86%). 3 arises from 5-norbornene-2-endo-diazonium ions (2) as shown by the nitrous acid deamination of the epimeric amines 1 and 7. 3-Norpinen-2-one (12) was isolated by oxidation of the deamination products followed by preparative g.1.c. 3 and 12 were synthesized independenrly from norpinan-2-one (9) via sulfenylation and sulfoxide pyrolysis. The norbornene + norpinene rearrangement is slightly enhanced by 1 -OCH3. The deamination of l-methoxy-5-norbornen-2-endo-amine (14) produced 10% of 12, as compared to 5.6% of 3 from 1. sylhydrazon (4) in Natronlauge/l,2-Dimethoxyethan. Die GC-Analyse der Produkte zeigte nur 5-Norbornen-2-01 (5) und Nortricyclanol (6). Nach katalytischer Hydrierung fanden wir neben 6 und 2-Norbornanol (aus 5 ) auch 1.2% 2-Norpinanol, das vermutlich aus 3-Norpinen-2-01 (3) entstanden war. Die Bildung von 3 durch Wanderung von C-7 erschien demnach unbedeutend. Kationische Umlagerungen von

Norpinyl-Norbornyl Rearrangements:Resonance-Stabilized Ricyclo~3.l.l]hept-2-yl Cations 2-Phenylbicyclo[3.1 .l]hept-2-yl cations (Sc), generated by solvolysis of the 4-nitrobenzoate 8, undergo norpinyl-norbornyl rearrangement to a minor extent ( < 6 % in water, < I % in methanol). The acid-catalyzed alkoxy exchange of 2,2-dimethoxybicyclo[3.1 .l]heptane (13) proceeds without skeletal rearrangement. The solvolysis of bicyclo(3.1 .l]hept-3-en-2-yl-4-nitrobenzoate (19) is complicated by 0-acyl cleavage but the hydrolysis of the allylic bromide 21 and the nitrous acid deamination of the corresponding amine give bicyclo[3.1 .l]hept-3-en-2-01 (18) exclusively.

Eingegangen am 1. Oktober 1980 3-, 5-, 6-und 7-Methylnorbornan-2-diazonium-lonen wurden als exolendo-Gemische durch Photolyse der entsprechenden Methyl-2-norbornanon-tosylhydrazone (3, 5, 23, 27, 32, 34,45, 47) in wanriger Natronlauge erzeugt. Die Zusammensetzung der Methyl-2-exo-norbornanole zeigte vollstandige Wagner-Meerwein-Aquilibrierung der kationischen Zwischenstufen. 6.2-H-Verschiebungen zwischen sekundaren Kationen waren unter diesen Bedingungen relativ langsam, doch war die Bildung des tertiaren Kations 54 eine Hauptreaktion der 6-Methyl-2-norbornan-diazoniumlonen. 3,2-H-Verschiebungen zwischen sekundaren Kationen wurden nicht beobachtet; aus 3-Methyl-2-norbornan-diazonium-Ionen erhielt man weniger als 240 tertiaren Alkohol. Methyl-2-endo-norbornanole mit der Konstitution des Ausgangsmaterials wurden ebenfalls gefunden. Die Desaminierung der stereoisomeren 3-Methyl-2-norbornylamine (59, 60, 67, 70) in wanriger Perchlorsaure zeigte, dan endo-Alkohole nur aus endo-Diazonium-lonen entstanden. Die Stellung der 3-Methylgruppe hatte einen starken Einflun auf die Ausbeute an endo-Alkohol (58% aus 59 gegen 7% aus 70). Ein neuer Reaktionsweg zu den endo-Alkoholen wird vorgeschlagen. Deamination Reactions, 36 1)Decomposition of Methylnorbornane-Zdiazonium Ions .3-, 5-, 6-and 7-Methylnorbornane-2-diazonium ions were generated as exolendo mixtures by photolysis of the corresponding methyl-2-norbornanone tosylhydrazones (3,5,23,27,32,34,45, 47) in aqueous sodium hydroxide. The composition of the meth>l-2-exo-norbornanols indicated virtually complete Wagner-Meerwein equilibration of the cationic intermediates. 6,2-H shifts between secondary cations were rather slow under these conditions, but formation of the tertiary cation 54 was a major reaction of &methyl-2-norbornanediazonium ions. 3.2-H shifts between secondary cations were not observed and less than 2% of tertiary alcohol was produced from 3-methyl-2-norbornanediazonium ions. Methyl-2-endo-norbornanols of retained constitution were also found. Deamination of the stereoisomeric 3-methyl-2-norbornylamines (59,60,67, 70) in aqueous perchloric acid revealed that endo alcohols arose from endo diazonium ions only. The position of the 3-methyl group strongly affected the yield of endo alcohol (58% from 59 vs. 7% from 70). A novel reaction path to the endo alcohols is suggested.Die Solvolyse von 2-exo-und -endo-Norbornylbrosylat ergibt ausschliefllich 2-exoNorbornanol bzw. dessen Ester2). Dagegen erhalt man bei der Desaminierung der 2-Norbornylarnine auch e n d o -P r o d~k t e~*~) .Das abweichende Verhalten von Sulfonsaureestern und Diazonium-Ionen kornpliziert die Diskussion uber offene oder verChem. Ber. 114(1981)