Synthesis of Biphenanthrenyls and Role of C−H···X Noncovalent Interactions in Conformational Control

Abstract

A convenient synthesis of the 1,2Ј-biphenanthrenyls 4a−c,f, 1,3Ј-biphenanthrenyls 4d,e, thiabiphenanthrenyl 4g, the benzo[h]chromen-2-ylideneacetonitrile 5a and the methyl benzo[h]chromen-2-ylideneacetate 5b through carbanion-induced ring transformation of 2H-pyran-2-ones 1 or 2 and the 1-naphthalenone 3a or thiochroman-4-one 3b separately is described. The structures of the biphenanthrenyls 4b and 4c

Sequential approach to the synthesis of ‘U and Z’ shaped polycyclic heteroarenes

“…It was interesting to note that the stability of the compound 3 towards amine at reflux temperature in ethanol as well as methanol was poor and gave two ring opened products 5 and 3-methylthio-3(2-pyrrolidin-1-yl)-3,4-dihydronaphthalen-1-yl)acrylonitrile (6). Our past study on X-ray diffraction of 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles 11 has shown an intramolecular C-H⋯O interaction between the ortho-proton of the 6-aryl group and the nuclear oxygen of the pyran ring which provides stability 11 to the molecule, while in the case of lactone 3 no such interaction exists and this could be the reason for instability and the poor yield of product 4. pyrano [2,3-d]oxepine-3-carbonitriles (10), 12 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo[b]pyrano [2,3-d] oxepine-3-carbonitriles (11) and 4-sec-amino-2-oxo- 2,5-dihydrothiochromeno[4,3-b]pyran-3-carbonitriles ( 16) were used as intermediates for the construction of 'Z' shaped aza-oxaand aza-oxa-thiaheterocycles 12 and 17. The intermediate 10 was obtained from the reaction of benzo [b]oxepin-5-one (9) with methyl 2-cyano-3,3-dimethylthioacrylate (2).…”

“…The intermediate 10 was obtained from the reaction of benzo [b]oxepin-5-one (9) with methyl 2-cyano-3,3-dimethylthioacrylate (2). Amination of 10 with sec-amine in refluxing methanol afforded 4-sec-amino-2oxo-5,6-dihydro-2H-benzo [b]pyrano [2,3-d]oxepine-3-carbonitrile 12 (11). Further, reaction of 10 with amidine in DMF using powdered KOH as a base at room temperature yielded a product that was characterized as 4-amino-2-aryl-5-oxo-12,13-dihydro-5Hbenzo [b]oxepino [5,4-b]pyrimido [4,5-d]pyrans (12) in place of the anticipated product 2-aryl-4-sec-amino-5,6-dihydrobenzo [b]pyridino [2,3-d]oxepine-3-carbonitrile ( 13) possibly due to steric factor, Scheme 2.…”

“…The molecular make up of 4-methylthio-2-oxo-5,6-dihydro-2H-benzo [b]pyrano [2,3-d]oxepine-3-carbonitriles ( 10) and 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo [b]pyrano [2,3-d]oxepine-3-carbonitriles 12a (11) revealed the presence of three electrophilic sites C-2, C-4 and C-11b in which the latter is more likely electron deficient due to extended conjugation and the presence of an electron withdrawing substituent at position 3 of the lactone ring.…”

“…Thus, C-11b position seems vulnerable to nucleophilic attack but practically reaction takes place at the C-4 position with formation of the Michael adduct followed by condensation-cyclization to yield 12. Possibly the intramolecular C-H⋯O interaction 11 between nuclear oxygen and ortho hydrogen of aryl ring plays a significant role in facilitating the reaction at C-4 site. A plausible reaction mechanism for the reaction is shown in the Scheme 3.…”

Synthesis of Phenanthrene Derivatives through the Reaction of an α,α‐Dicyanoolefin with α,β‐Unsaturated Carbonyl Compounds

“…In addition,s tudies on various substituted phenanthrene derivatives reveal that they exhibit tumor-inhibitory potential [6], cytotoxicity [ 7],a nd anti-inflammatory properties [8].M oreover, phenanthrene derivatives are well knownh ydrocarbons found in crude oil [9], soil, and sea sediments [10]. As aconsequence,many approaches to this structure have been disclosed in the literature.T he traditional pathway is the Haworth synthesis,w hich contains aseries of stepsincluding FriedelÀCrafts acylation,followed by a Clemmensen reduction or WolffÀKishner reduction,c yclization, reduction, and dehydrogenation [11].O ther reliable strategiest op henanthrenes are intramolecular condensations of disubstituted biphenyls [12], photocyclization of stilbenes [ 13], Pd-catalyzed cyclization of aryneswith alkynes [14], base-catalyzedring transformation of 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles [15], carbanion-induced ring transformation of 2H-pyran-2-ones and 1-naphthalenone [16], and one-potm ulticomponent reactionsofaldehydes,malononitrile,1-tetralone,and NH 4 OH [17]. Most of these procedures suffer from the limitation of availability of precursors,l ow yields, harsh reaction conditions,a nd low functional group tolerance.…”