Unsaturated heterocyclic systems. XCII. Nitrogen analogs of 1,6-methano[12]annulene. Effect on valence tautomerism of the locus of aza substitution

Silver(I) ion catalyzed rearrangements of strained .sigma. bonds. 33. Benzoannulation as a probe of structural dimension and .pi.-electron distribution in elassovalenes. A mathematical model for the assessment of homoaromaticity

“…Preparative VPC work was done on a Varían-Aerograph A90-P3 instrument equipped with a thermal conductivity detector. 2.3-Benzo-A2,6-hexalin-9,10-dicarboxylic Anhydride (8). A mixture of 5.0 g (48 mmol) of benzocyclobutene (6),12 5.0 g (33.3 mmol) of 1,4-cyclohexadiene-1,2-dicarboxylic anhydride (7),13 and 10 mL of toluene was heated in a sealed tube at 170 °C for 48 h in a rocking autoclave.…”

“…Variable-Temperature NMR Data (100 MHz, CS2), Computed Equilibrium Constants (ATeq), and Gibbs Free Energy Values (AG°) for the Fluxional System 17a $2 17b°t o possess structure 18 by simple sublimation. The relative yields of 8 and 18 were understandably related directly to the molar ratio of 6 to 7 which therefore had to be rather strictly controlled for our purposes (see Experimental Section). Conversion of 8 to sulfide 10, followed by Ramberg-Backlund rearrangement,14 led efficiently to 12, bromination-dehydrobromination of which afforded 13.…”

Recent developments in the synthetic uses of chlorosulfonyl isocyanate

“…84 A detailed study utilizing model compounds should allow accurate assignments to be made to reaction products of polyisoprene and CSI. 79 The compounds C2H5(CH2C(CH3) =CHCH2)nC2H5 ( = 1 and 2) were chosen as models for 1,4-polyisoprene, while CH2=C(CH3)CH(C2H5)2 was the model for 3,4-polyisoprene. The products obtained indicate that the reaction may be more complicated than previously reported.43•44 A mechanistic rationale is provided79 which may have implications for other CSI-olefin interactions as well.…”

The Realities of Extended Homoaromaticity

“…The bridged system (45 a ) has, however, been generated in superacidic media from a variety of alcohol precursors such as (46a), (47a), and(48)[78-801. Its monomethyl derivative (45 b ) has been comparably prepared from (46b) and (47b)["], as well as by protonation of (49)-…”