Diphenylmethylene moiety

Funher. structural modification of cla.s.sic antimuscarinic agents can be found in the drugs described below. Each of them has the typical bulky group characteristic of the usual anticholinergic molecule. One modification is represented by ibe diphenylmethylene moiety (e.g.. diphcmanil) a sec-... 

Photochemical cyclization occurs by a conrotatory mechanism, while thermal cyclization occurs by a disrotatory one. In the symmetrical fulgide / 7 -ArF2, the phenyl substituents of both benzylidene groups participate in the reaction with equal probability. In unsymmetrical benzylidene(diphenylmethylene)-succinic anhydride, -ArFl, only one phenyl substituent of the diphenylmethylene moiety participates both in thermo- and in photochemical reactions. The selectivity of such a transformation is not determined by a rule of orbital symmetry preservation, so it was suggested that it may be related to the specific spatial structure ofArFl.81... 

Figure 4.9 Fluorinated polyamides containing diphenylmethylene moiety [49].

The (diphenylmethylene)aminocyclobutenecarboxylates 109 obtained by rearrangement of the DMPA-H adducts of 1-Me, 2-Me, contain a 2-azadiene unit and a cyclobutene moiety. Indeed, the parent compound 109 a reacted with 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD, [80]) at room temperature in a [4-1-2] cycloaddition mode to yield the tricyclic tetraazaundecene 132 in almost quantitative yield (Scheme 44) [8]. As substituted cyclobutenes, compounds 109 should be capable of opening up to the corresponding butadienes [1, 2b, 811. When compounds 109 were subjected to flash vacuum pyrolysis, the dihydro-isoquinolines 135 were obtained, presumably via the expected ring-opened intermediates 133, which subsequently underwent bn electrocyclization followed by a 1,5-shift, as is common for other 3-aza-l,3,5-hexatrienes [82]. 

Although both the symmetrically substituted azomethine carbon and the symmetry of the sulfonyl moiety of A-(diphenyl-methylene)-4-methylbenzenesulfonamide (2) limit its use in asymmetric synthesis, (25)-(V- l,l-diphenyl-[(, -3-(/ toluene-sutfinyl)phenyl]propyl)-/>-toluenesutfonamide (19) has been obtained in almost quantitative yield (94%) and with complete stereoselectivity (de > 98%) in the reaction of enantiopure Li carbanion from (5)-2-(/>-toluenesutfinyl)ethylbenzene (18) and 7V-(diphenylmethylene)-4-methylbenzenesulfonamide (eq 11), with the TV sulhnylimine analog being a factor of 2 less reactive under the same reaction condihons. 

Tartaric Acid-Derived Quaternary Ammonium Salts Starting from the freely available tartaric acid, Shibasaki et al. designed and prepared a series of diammonium salts by changing the acetal moieties (R and R ), aromatic parts (Ar), and counteranions (X) (Figure 12.11). Screening of the catalyst hbrary identified that catalyst 48a was efficient for the asymmetric alkylation of N-(diphenylmethylene) glycine tert-butyl ester [81] and that the C2-symmetric catalysts 48b, 49, and 50 were efficient for the conjugate addition [82]. 

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