4H-3,1-benzoxazoles. 4. Examination of the formation of 1,2-dihydro-4h-3,1-benzoxazines using tagged atoms

Studies of 4H-3,1-benzoxazines. 14. Structure and some properties of 2-[2-hydroxyphenyl(naphthyl)]-1,2-dihydro-4H-3,1-benzoxazines

“…Initial mass spectroscopic decomposition of M + in compounds 5a,d,h,j, 6b occurs with fission of 2-hydroxybenz(naphth)oyl (RDD + H process [4]) and aliphatic R and R 3 radicals to give the cations Φ 4 , Φ 7 , and Φ 9 respectively. According to the mechanism of interaction of aminoalcohols with aldehydes [10,11] the first stage in the formation of the 3,1-benzoxazino [1,2-c] [1,3]benz(naphth)oxazines 5a-j, 6a-d is likely a nucleophilic addition of the amino group of the dihydrobenz(naphth)oxazines 3a-d, 4a,b to the carbonyl carbon to form the intermediate C (see Scheme 1). Further reaction can then occur by two routes which are determined by the structure both of the benzoxazines and the aldehyde.…”

Investigations in the field of benzoxa- zines. 15*. Tandem heterocyclizations with the participion of 2-formylbenzoic acid. The synthesis of isoindolo[1,2-b][1, 3]- and -[2,1-a][1, 3]benzoxazinones

“…The reaction of equimolar amounts of the formylbenzoic acids 1 and 2-aminophenylcarbinols 4a-c in acetic acid [15,16] give the isoindolobenzoxazinones 5 in a single stage without separation of intermediate products. The reaction also occurs readily in toluene in the presence of a catalytic amount of p-toluenesulfonic acid but, in this case, an additional operations is needed for neutralization of the catalyst and removal of solvent.…”