Fused bridged

Taylor has collected the above and similar data and compared the ratio of reactivities of the ortho and para positions of compounds of type 19 (expressed as log/odog/p) with the ratio of reactivities of the equivalent positions, a and c, in compounds of type 20 and found that the latter ratio was lower, i.e., a relative increase in the reactivity of the para position (c) has occurred upon ring formation. This fall in the ratio log fa log fc increases along the series X = S < 0 (< NH < CHg) in 20. As this trend parallels the increase in strain in the fused bridging ring it was argued that ring strain was the primary cause of the reduction in ratio. Position a is a-aromatic and position c is j8-aromatic therefore the above concept represents an extension by Taylor of an earlier explanation of the Mills-Nixon effect in indane. Further substitution... 

Fused bridge prevents isomerisation and provides thermal and photochemical stability I------------------------------1... 

This section covers the reactivity of nonconjugated fused, bridged, and bicyclic 1,2,5-triheteropine rings. 

Acid hydrolysis of the diester 10 gave a 1 1 mixture of the diazocinium salt 8 and a triamino-substituted cyclohexane derivative (Equation 1) <1997J(P2)1445> whereas, acid hydrolysis of the indolo-fused diazocines 7a and 7b afforded, in good yields, the isomerization products indolo-fused bridged diazocines 11a and lib (Equation 2) C1995TL1693, 1996T3563>. 

The same type of isomerization was observed in the case of the indolo-fused bridged 1,3-diazocines 12, which, upon action of trifluoroacetic acid (TFA), quantitatively rearranged to the indolo-azocine 13 (Equation 3)... 

Preparation of Fused, Bridged and Spiro Bi- and Tricyclic Amines... 

Diyl spin state Diylophile Fused bridged ratio Trans.cis rand ... 

For example, the singlet trimethylenemethane 6.365 can be produced by heating the strained bicyclic hydrocarbon 6.363 or the diazene 6.364, or by photolysis of the latter. It dimerises to give a mixture of at least three hydrocarbons out of the eight possible, of which one stereoisomer of the fused-bridged product 6.366 is the major. The exocyclic methylene carbon is the unique carbon, and can be assigned to be the one with the large coefficient in ip2 and a zero coefficient in The experimental result can then be explained if the former is the HOMO and the latter the LUMO.873... 

Reductive cyclization. Azide redu addition of the resulting amine to a a assemblage of fused-bridged tricycles hai synthesis of (—)-cylindricine. 

Note. Of the many little-known and complicated fused, bridged, or spiro systems mentioned in chapters 4-9 and 11, only a few representatives are indexed. 

Fused Fused Fused Fused Fused Bridged Core... 

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