New method for the synthesis of substituted anthranils

Transformations of para-Substituted Benzylcyclopropanes, Allylbenzenes, and Diphenylmethanes under Nitration with Nitric Acid in Acetic Anhydride

“…Insofar as the latter cannot eliminate the cyclopropyl group, it is converted into 4-allyl-2-nitrophenylcyclopropane (LVIII) via ~1,2-shift of the nitro group. This assumption is supported by the data of [18] according to which the relative contribution of ipso-attack by NO 2 + ion on the cyclopropyl-substituted carbon atom in 4-cyclopropylanisole is considerably greater than the relative contribution of ipso-attack on the methyl-substituted position in 4-methylanisole. On the other hand, the nitration of compound LV according to the classical electrophilic substitution mechanism (Scheme 12) cannot be ruled out.…”

“…This also follows from the anomalously high ratio of nitrobenzylcyclopropanes XXIII and XXI. We previously showed [17] that the nitration of 4-methoxyphenylcyclopropane (XXVII) with anhydrous nitric acid in acetic anhydride gives 4-methoxy-3-nitrophenylcyclopropane (XXIX) in almost quantitative yield. According to the data of [9,18], the transformation of XXVII into nitro compound XXIX involves initial formation of a considerable amount (no less than 70%) of σ-complex XXVIII (Scheme 7).…”

“…We previously showed [17] that the nitration of 4-methoxyphenylcyclopropane (XXVII) with anhydrous nitric acid in acetic anhydride gives 4-methoxy-3-nitrophenylcyclopropane (XXIX) in almost quantitative yield. According to the data of [9,18], the transformation of XXVII into nitro compound XXIX involves initial formation of a considerable amount (no less than 70%) of σ-complex XXVIII (Scheme 7). Without going into details how σ-complex XXVIII is converted into the final product (this problem has not been solved unambiguously as yet), we can state with a high degree of certainty that cyclopropyl group cannot be eliminated from the geminal entity in σ-complex XXVIII under the given conditions.…”

4H-3,1-benzoxazines from o-aminoacylbenzenes

“…2-Amino-5-chloropropiophenone (8) was obtained in 92% yield; mp 80°C (from ethanol) as described in our previous work [10].…”

“…However, studies have recently appeared showing that this problem may be circumvented, sometimes by well-known reactions, and the desired 2-aminoacylbenzenes may be obtained in high yield. For example, the reported acid-catalyzed rearrangement of variously substituted 2-nitrophenylcyclopropanes 1 and 2 gives 2-nitrosopropiophenones 3 and 4, which may be transformed to yield a broad range of 2-aminopropiophenones 6-8 [8][9][10] (10), which is the product of the nitration of 1-(4-tert-butylphenyl)ethanol (9), undergoes a similar rearrangement to give 4-tert-butyl-2-nitrosoaceto-phenone (11) [11]. We are the first to report the synthesis of 2-amino-4-tert-butylacetophenone (12) by the reduction of 11.…”