A c i d -C a t a l y z e d T r a n s f o r m a t i o n s o f t e r t -N -F u r f u r y l c a r b o x a m i d e sAbstract: Acid-catalyzed transformations of tertiary N-furfurylamides of ortho-amino substituted aromatic and heteroaromatic carboxylic acids accompanied by elimination of the furfuryl moiety are investigated.Furan derivatives have been widely applied as useful building blocks in carbo-and heterocyclic compound chemistry for many years and there are numerous reviews devoted to their synthetic application. 1 We have studied the usage of furan compounds for annelated heterocyclic systems synthesis. 2In a preceding paper 3 we presented a new method for the synthesis of pyrrolo[1,2-a]diazepinone derivatives, based on acid-catalyzed transformations of N-One of the advantageous features of our method is the simultaneous formation both of diazepine and pyrrole rings as a result of a furan ring recyclization (Scheme 1).Some pyrrolo[1,2-a][1,4]diazepine derivatives show a wide range of biological activity, including anxiolytic, 4 sedative and antiepileptic activities; 5 they also affect the central nervous system. 6 A number of pyrrolo[1,2-a] [1,4]diazepinone derivatives possess analgesic action, 7 and act as antibacterial 8 and anti-fungal agents with high specificity towards dermatophytes. 9Since diazepine derivatives are of interest in the search for new biologically active compounds and precursors for the manufacture of new medicines, an extension of the developed approach towards the preparation of new pyrrolodiazepines became our main aim.Herein we report our results on acid-catalyzed transformations of tertiary N-furfuryl-containing amino amides of aromatic and heteroaromatic carboxylic acids with an amino function in the ortho position to a carboxy group.As starting compounds we used tertiary amides of orthoaminobenzoic acids 3, which were prepared from secondary furfurylamines 1 according to Scheme 2. 3 We also used N2-substituted N2-(5-methyl-2-furylmethyl)-3-aminothieno[2,3-b]pyridine-2-carboxamides 6, which were synthesized from pyridinethiones 4 and the corresponding furfurylchloroacetamides 5 under Thorpe-Ziegler conditions (Scheme 3). 3,10

3‐Acylaminofuro[2,3‐b]pyridine derivatives have been synthesized, and their behavior under acidic and basic conditions was studied. A new base‐catalyzed rearrangement of 3‐acylaminofuro[2,3‐b]pyridine derivatives into 3‐(oxazol‐4‐yl)pyridine‐2‐ones has been founded.

Tertiary N-furfurylamides of ortho-amino substituted aromatic and heteroaromatic amides are synthesized. Their acid-catalyzed transformations are accompanied by elimination of the furfuryl moiety. -(STROGANOVA*, T. A.; VASILIN, V. K.; ZELENSKAYA, E. A.; RED'KIN, V. M.; KRAPIVIN, G. D.; Synthesis 2008, 19, 3088-3098; Dep. Org. Chem., Kuban State Technol. Univ., Krasnodar 350072, Russia; Eng.) -Mais 05-100

Pyrrolo[1,2-a] [1,4]diazepine derivatives are of interest from the viewpoint of searching for and developing novel substances with a variety of types of biological activity. For many years this fact has stimulated an active search for methods of synthesizing and modifying compounds of this class [1].It is known [2-4] that the thiophene ring in a thienopyridine fragment can readily undergo desulfurization with opening of the thiophene ring. In this work we report results of a study of the condensed pyrrolodiazepines transformation which contain a thieno[2,3-b]pyridine fragment.Amongst these derivatives we have examined the tetracyclic system of pyridothienopyrrolodiazepines 1a,b prepared by recyclization of N-(5-methylfuran-2-yl)methyl-substituted derivatives of 3-aminothieno[2,3-b]-pyridine amides using a known method [5] and we have looked at their reactions in the presence of Raney nickel.It was found that refluxing the diazepines 1a,b in ethanol in the presence of activated Raney nickel gave the desulfurization products, pyrrolodiazepines 2a,b which contain a pyridine ring conjugated to the diazepine fragment and whose structures were proved using NMR and mass spectrometric methods N S Me R Me NH 2 O N H O Me HCl / AcOH N S Me R Me NH N O Me N Me R Me NH N O Me EtOH 1a,b 60 o C 2a,bRaney Ni, 1,2a R = H, b R = Br 1 H and 13 C NMR spectra were recorded on a Bruker AM-300 instrument (300 and 75 MHz respectively) using DMSO-d 6 with TMS as internal standard. Mass spectra were taken on a Kratos MS-30 spectrometer with direct introduction of the sample into the ion source (EI, 70 eV).Compounds 1a,b were prepared by the method reported in [4]. Melting points and spectroscopic data agreed with those in the literature.

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