FUNCTIONALIZED ENANTIOMERICALLY PURE [1.1.1]TRIBLATTANE, [2.1.1]TRIBLATTANE, [2.2.1]TRIBLATTANE AND [2.2.2]TRIBLATTANE

The methylene (2,7, 10) and spirocyclopropane derivatives (8, 11, 12) are made accessible from rac-trishomocubane(mone-, di-, tri-)ones and optically pure unsaturated and benzoannulated [2.1.1]- (19, 48), [2.2. 1]- (30, 53), and D3-symmetrical [2.2.2]triblattanes (3, 4) from the e nantiomers of these ketones by expeditious (one pot) ring enlargement and olefination procedures. In the case of the central [2.2.2]trienes (+)-3/(-)-3, novel members of the (CH)14 family, optical resolution is advantageously postponed to the stage of the intermediate [2.2.2]trio nes (35, 41) and effected via their (R,R)-2,3-butanediol acetals. In t he alpha-diketone series only the [2.1.1]dione (70) is sufficiently st able to allow isolation; tetrone 73 and hexone 5 are indirectly identi fied as quinoxalines 74 and 76, respectively. Tribenzo[2.2.2]triblatta ne (-)-4 is established as the M-helical enantiomer by X-ray crystallo graphy. Generally the thermal stabilization pathway of unsaturated and benzoannulated triblattanes is a [4 + 2] cycloreversion with the prim ary cycloreversion products [e.g. cy-clo[8.4.0.0(2,7)]tetradeca-3,5,9, 11,13-pentaene (78) from rac-3] being unstable under the drastic react ion conditions required. The stereochemical course of the perepoxidati on of rac-3 is investigated.