0000000000407054
AUTHOR
H.‐l. Eckes
Cycloadditionen von Benzothiet und aromatischen Nitroso‐Verbindungen
Cycloaddition Reactions of Benzothiete and Aromatic Nitroso Compounds The new heterocyclic ring systems 4H-3,1,2-benzoxathiazines 4 and 2,3-dihydro-1,2-benzothiazol 1-oxides 6 can be synthesized by cycloaddition of benzothiete (1) and aromatic nitroso compounds 3. The regioselectivity of the primary step and the secondary thermal or acid-catalyzed rearrangements are discussed.
Addition von Phosphor‐Nucleophilen an Benzothiet
Addition Reactions of Phosphorus Nucleophiles to Benzothiete Trialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement – related to the Arbuzov reaction – can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a–d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a – d. An intramolecular rearrangement in a 1:1 adduct is only obse…
Reactions of benzothiete with phosphorus nucleophiles - a novel type of arbuzov rearrangement
The reaction of trialkylphosphites or related P-nucleophiles with benzothiete (1) leads to zwitter ionic species, which show an Arbuzov - like rearrangement to the products 4 and 7, respectively. New heterocyclic ring systems are generated in the case of cyclic esters. The normal SN2 reaction leads to the 1:2 adducts 9, whereas in an SN1 process the 1:1 adduct 13 is formed.
Naphthalenophane durch doppelte Photocyclodimerisierung von Distyrylnaphthalinen
Bei der Belichtung von Distyrylnaphthalinen entstehen in regiospezifischen Kopf-Kopf-Cycloadditionen Naphthalenophane. Je nach Stellung der Styryl-Gruppen beobachtet man vollkommen stereospezifische Prozesse (1d 2, 1g 3, 1h 4) und Dimerisierungen mit partiellen Stereoselektivitaten (1b 5–8, 1i 9, 10). Masgeblich sind die Rotamerenpopulation im Ausgangsprodukt 1 und die elektronischen und sterischen Effekte in den Excimeren. Prinzipiell sind Excimere mit paralleler Anordnung moglichst vieler π-Zentren bevorzugt — ein experimenteller Befund, der durch HMO-Rechnungen untermauert wird. Naphthalenophanes by Twofold Photocyclodimerizatio Reactions of Distyrylanaphthalenes Regiospecific head-to-he…
ChemInform Abstract: Reactions of Benzothiete with Phosphorus Nucleophiles. A Novel Type of Arbuzov Rearrangement.
The reaction of trialkylphosphites or related P-nucleophiles with benzothiete (1) leads to zwitter ionic species, which show an Arbuzov - like rearrangement to the products 4 and 7, respectively. New heterocyclic ring systems are generated in the case of cyclic esters. The normal SN2 reaction leads to the 1:2 adducts 9, whereas in an SN1 process the 1:1 adduct 13 is formed.
Cycloaddition von Benzothiet an 4‐substituierte Styrole
Durch thermische Ringoffnung entsteht aus Benzothiet (1) ein 8-π-Elektronensystem 2, das mit den 4-substituierten Styrolen 3a–j die Cycloaddukte 4/5a–j bildet. Die Erhohung der Reaktivitat durch elektronenspendende oder elektronenanziehende Reste und die Einflusse auf die Regioselektivitat werden an Hand von Grenzorbitalbetrachtungen diskutiert. Cycloaddition of Benzothiete of 4-Substituted Styrenes By thermal ring opening benzothiete (1) generates an 8-π electron system 2, which forms the cycloadducts 4/5a–j with 4-substituted styrenes 3a–j. The enhancement of the reactivity by electrondonating as well as electron-withdrawing substituents and their influence on the regioselectivity are dis…