Furo benzothiazepines

The same authors recently reported the synthesis of l//,3//-furo[3,4-b [ 1,5]benzothiazepin-l-one (35) by cyclizing butanolide 34 in the presence of triethylamine hydrochloride at 170°C and removing the methanol and water formed during the reaction. When the cyclization reaction was performed at about 140°C without removal of methanol and water, compound 35 was obtained in only 9% yield, and the major product was 37 (31%), a methanol adduct to 35. The reduction of the C=N bond of 35 with sodium borohydride and the subsequent spontaneous oxidation gave sulfoxide 36 (92MI1) (Scheme 11). 

Dihydro-l.//,3/f-furo[3,4-c][l, 5]benzothiazepin-l-ones (39) have been obtained by the heteroannelation reaction between 5 and 3-arylmeth-... 

Chroman 6-Amino-4-oxo-2-(2-thienyl)- VI/4, 154f. Furo[3,4-b]-l,5-benzothiazepin ... 

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