Synthesis of Novel 13a‐(ω‐Aminoalkyl)‐8‐oxoberbines by Means of Reaction of Homophthalic Anhydride with 1‐Substituted 3,4‐Dihydroisoquinolines. An Unexpected Formation of a Pyrrolo[3,4‐i]berbindione

One-step route to tricyclic fused 1,2,3,4-tetrahydroisoquinoline systems via the Castagnoli–Cushman protocol

“…Previous knowledge on the reaction between monocyclic anhydrides 5, 6 and 7 and Schiff bases indicated the necessity of elevated temperatures for conducting the reaction as the yields of the target products increased with the temperature [32][33][34]. The anhydride was taken in slight molar excess in analogy to our previous work [21].…”

“…The Castagnoli-Cushman reaction (CCR) between cyclic enolizable anhydrides (such as succinic (5) [9], glutaric (6) [10], and the corresponding oxygen (7) [11], sulfur (8) [11], and nitrogen analogs 9 [12], and homophthalic anhydride (10) [13,14]) and imines 11, 12 offers a route to substituted lactam molecules 13 and 14 [13][14][15][16][17][18][19]. Among them, the reactions of homophthalic anhydride (10) with Schiff bases 11 or cyclic imines 12 have been examined in detail (Scheme 1) [13,14,20,21].…”

“…While the reactions of homophthalic anhydride (10) and various cyclic imines 12 have been extensively explored [13,21,24,25], there are only few reports featuring reactions between monocyclic anhydrides 5-9 and cyclic imines 12 in the literature [12,[25][26][27][28][29]. Thus, it was shown that glutaconic anhydride reacts with 1-methyl-3,4-dihydroisoquinoline and with 1-chloroisoquinoline to give 11b-methylbenzo[a]quinolizin-4-one [28] and benzo[a]quinolizin-4-one [27], respectively, in moderate yields.…”

Novel angularly substituted [1,4]thiazino[3,4‐a]isoquinoline carboxylic acids prepared by cyclic imine‐cyclic anhydride reaction

“…The reaction conditions were chosen based on our previous work. [4,12] The reaction mixtures were monitored by TLC until the starting imines 6 reacted completely (2-6 h). The obtained target compounds were purified by column chromatography of the reaction mixtures followed by recrystallization (Table 1).…”

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

“…The use of cyclic imines (or surrogates thereof such as isoquinoline [ 11 ]) in the CCR is quite scarce in the literature [ 12 – 14 ]. As an example, 1-pyrroline (in the form of its trimer 3 ) has been reported by Smith and co-workers [ 15 – 17 ] to condense efficiently with HPA analogs to deliver hexahydropyrrolo[1,2- b ]isoquinolones 4 .…”