ChemInform Abstract: Synthesis of Spiro‐Linked Cyclopropanes.

Abstract

ChemInform Abstract The title compounds (VI), (VII) and (IX) are prepared by novel, convenient and effective procedure.

Linear and Branched Phospha[n]triangulanes

“…CuCl (99 % purity) was purchased from Acros and stored under nitrogen before use. (5,6-Dimethyl-2,3-bis(methoxycarbonyl)-7-phenyl-7-phosphanorbornadiene) pentacarbonyltungsten (8), [9,13] methylenespiropentane (9), [28] 1-methylenedispiro-[2.0.2.1]heptane (10), [29] 7-methylenedispiro[2.0.2.1]heptane (11), [29,30] 1,4-bismethylenespiropentane (15), [31] perspirocyclopropanated bicyclopropylidene 18, [3] cyclopropylidenespiropentane (20), [32] 7-cyclopropylidenedispiro[2.0.2.1]heptane (22), [30] and ethenylbicyclopropylidene (25) [33] were prepared according to literature procedures.…”

The First Enantiomerically Pure Triangulane (M)-Trispiro[2.0.0.2.1.1]nonane Is a σ-[4]Helicene

“…Thus [4]triangulane is a true ªs- [4]heliceneº, the first s-bond analogue of the aromatic [n]helicenes, which have a helical arrangement of skeletal p bond and should therefore be termed p-[n]helicenes to distinguish them from these newly established s-[n]helicenes. [35] With the same type of computations it is predicted that the rotatory strength of the next higher analogue in the series of chiral triangulanes, (M)- [5]triangulane ((M)-12), should be about twice as large (by a factor of 1.8) as that of (M)-2, whereas the rotatory strength of (M)- [6]triangulane ((M)-13) would only be slightly larger (factor of 1.1) than that of (M)-12. This may have to do with the simple fact that the sum of interplanar angles between all adjacent pairs of spiro-fused cyclopropane rings reaches 3608 in (M)-12, while it is 2708 in (M)-2.…”

“…First bptz is a rigid molecule with two bipyridine units on each end suitable for bridging two metals, and second two bptz ligands coordinated to an octahedral metal center are required to be cis to each other. These binding preferences are being capitalized upon in one-pot, high-yield reactions of unprotected solvated cations [M(CH 3 CN) 6 ] 2 with bptz in the presence of tetrafluoroborate anions. In this study we report an unusual, high-yield formation of a cyclic product from solutions of [Ni(CH 3 CN) 6 ][BF 4 ] 2 and bptz in a 1:1 molar ratio [Eq.…”

“…(1)]. [6] [Ni(CH 3 CN) 6 4 ] 2 , the reactions proceed at room temperature in MeOH to give a dark green solution with eventual deposition of a green solid (74 % yield). Single crystals of the product are easily obtained by diffusion of toluene into a solution of the compound in acetonitrile.…”

“…[4] Racemic [4]triangulane (rac-2) was first synthesized over 25 years ago, [5] and in the meantime improved syntheses [6] as well as spectral, [7] structural, [8] and thermochemical properties [9] of rac-2 are sufficiently well documented. Essentially, the C 2 -symmetric molecule of (M)-2 is a section of a helix, so that the stereochemical descriptors for helicenes [10] should also be applicable to (M)-2 and extended unbranched triangulanes 1.…”