A concise synthesis of heteroaryl dibenzopyranones 9a,b, 10a,b, 11a−c, and 12a−c has been achieved by the LDA-induced migration of heterobiaryl O-carbamates 18, 21, 25, and 30 which, in turn, were prepared in good yield using a combined directed ortho lithiation (DoM)−transition-metal-catalyzed Suzuki cross-coupling strategy. An efficient and general route to a wide variety of heterocycles including coumestans 19a,c and the previously unknown isothiocoumestan ring system 22b has been thereby achieved.

Combined directed ortho and remote metalation-Suzuki cross-coupling strategies. Efficient synthesis of heteroaryl-fused benzopyranones from biaryl O-carbamates.

A new method for the synthesis of plurisubstituted pyrroles

An access to 1,3-azasiline-fused quinolinones via oxidative heteroannulation involving silyl C(sp3)–H functionalization

Synthetic studies on the CDEF ring system of lactonamycin

Aryl 2-bromobenzoates and aryl 2-bromocyclohex-1-enecarboxylates are cyclized by microwave irradiation in dimethylformamide in the presence of K2CO3 to give the corresponding 6H-benzo[c]chromen-6-ones and their 7,8,9,10-tetrahydro analogues, respectively, in 50–72% yields. Aryl 3-bromoacrylates are also converted into 2H-chromen-2-ones under the employed conditions.

Microwave-Assisted Cyclization under Mildly Basic Conditions: Synthesis of 6H-Benzo[c]chromen-6-ones and Their 7,8,9,10-Tetrahydro Analogues

Pyran‐Derivate, 96. [1]Benzopyrano[4,3‐b]pyrrol‐ und ‐pyridin‐Derivate

Die Mercapto- bzw. Methylamino-benzoyllactame 6a, 6b, 6d, 6e und 6f lassen sich durch Erhitzen in die Benzothiopyrano-pyrrolinone bzw. Pyrrolino-chinolinone 8a, 8b, 8d, 8e und 8f uberfuhren, wobei nach Pyridinhydrochlorid-Zusatz die N-Methylgruppe des Pyrrolinrings unter Bildung von 8c bzw. 8g abgespalten wird. Aus dem Acylpyridon 6i kann so das Tetrahydropyridino-chinolinon 18 gewonnen werden.



Die durch Hydrolyse der Acyllactame 6e, 6i bzw. 6d entstehenden Aminoalkyl-hydroxychinolinone bzw. Aminobenzoyl-γ-aminobuttersaure-Derivate 11 und 19 bzw. 13 lassen sich zu 8e und 20 bzw. 8d cyclisieren. Mit DDQ reagieren die Pyrrolin-Derivate 8b und 8e zu den Pyrrolen 15a und 15b.



Cyclisation of α-(2-Mercaptobenzoyl)- and α-(2-Aminobenzoyl)lactames; Synthesis of Benzothiopyranopyrrolinones and Pyrrolinoquinolinones



Compounds 8a, 8b, 8d, 8e and 8f are obtained by heating the mercaptobenzoyl- or methylaminobenzoyl-lactames 6a, 6b, 6d, 6e and 6f. With pyridine/HCI removal of the pyrroline N-methyl group takes place under formation of 8c and 8g. Cyclisation of the acyllactame 6i under the same conditions leads to the tetrahydropyridinoquinolinone 18. After hydrolysis of the acyllactames 6e, 6i or 6d the aminoalkyl(hydroxy)quinolinones or aminobenzoyl-γ-aminobutyric acid derivatives 11, 19 and 13 are isolated, which can be cyclized to8e, 20 and 8d. The pyrroles 15a and 15b are formed by dehydrogenation of the pyrroline derivates 8b and 8e with DDQ.

Zur Cyclisierung von α‐(2‐Mercapto‐ bzw. ‐2‐Amino‐benzoyl)‐lactamen; Synthese von Benzothiopyrano [4,3‐b]pyrrolinonen sowie von Pyrrolino‐ bzw. Tetrahydropyridino [3,2‐c] chinolinonen1)

Egmont Baumann

Papers

Pyran‐Derivate, 96. [1]Benzopyrano[4,3‐b]pyrrol‐ und ‐pyridin‐Derivate

Zur Cyclisierung von α‐(2‐Mercapto‐ bzw. ‐2‐Amino‐benzoyl)‐lactamen; Synthese von Benzothiopyrano [4,3‐b]pyrrolinonen sowie von Pyrrolino‐ bzw. Tetrahydropyridino [3,2‐c] chinolinonen1)