V. Vidyasagar

Thiele's ester as a reagent in organic synthesis. Preparation of pentacyclo[5.4.0.02,5.03,10.04,8]undecane-10-carboxylic acid

Abstract Succinyl cleavage of the C(2)–C(5) σ-bond in dimethyl pentacyclo[5.3.0.0 2,5 .0 3,9 .0 4,8 ]decane-2,5-dicarboxylate, 2 , afforded a tetracyclic diester, 3 (22–26%), along with two minor reaction products ( 4 and 5 ). Dieckmann condensation of 3 produced a mixture of 6a and 6b (67%). Wolff-Kishner reduction of the mixture of 6a and 6b thereby obtained afforded a mixture of products from which the title compound, 7b , could be isolated in 63% yield by fractional recrystallization. The structures of 3 , 4 and 7b were established unequivocally via X-ray crystallographic methods.

Synthesis and thermal rearrangement of pentacyclo[6.5.0.04,12.05,10.09,13]trideca-2,6-diene

Abstract Pentacyclo[6.5.0.0 4,12 .0 5,10 .0 9,13 ]trideca-2,6-diene ( 16 ) has been synthesized in five steps from 1-hydroxyhexacyclo[6.5.0.0 2,6 .0 3,11 .0 5,10 .0 9,12 ]tridecan-7-one ( 10 ). Compound 16 undergoes thermal rearrangement to pentacyclo[7.4.0.0 2,6 .0 3,11 .0 5,10 ]trideca-7,12-diene (i. e., “[2.2.1]triblattadiene”, 19 ). The intermediacy of cis,cisoid,cis -tricyclo[7.4.0.0 2,7 ]trideca-3,5,10,12-tetraene ( 18 ) in the thermal rearrangement of 16 was inferred via analysis of the 1 H NMR spectrum of partially rearranged 16 and subsequently was further established via the results of a trapping experiment (i. e., fluorene was produced when thermal rearrangement of 16 was performed in the presence of 10% Pd/C).

Synthesis and acid-promoted ring opening of a novel cage spiro-oxetane

When heated with glacial HOAc and concentrated H2SO4 (catalytic amount), cage oxetane 1 undergoes ring opening with concomitant skeletal rearrangement, thereby affording a mixture of bis(acetoxy)trishomocubanes, 7a and 8a (ratio 4:1).

On the mechanism of acid promoted ring opening of a pentacyclo[5.4.0.02,6.03,10.05,9]undecane-spiroannulated oxetane☆

Specifically deuterated cage-spiroannulated oxetanes 1a and 1b each undergo ring opening with concomitant skeletal rearrangement when heated with glacial HOAc in the presence of a catalytic amount of concentrated H2SO4. The fate of the deuterium atom in each substrate, as determined via analysis of the NMR spectra of the rearrangement products, establishes unequivocally that a key step in this process proceeds via highly stereoselective intramolecular 1,5-hydride transfer.

Synthesis of hexacyclo[7.4.0.02,8.03,7.06,11]Tridecane-10,13-dione(“homosecohexaprismane-10,13-dione”)

Abstract HEXACYCLO[7.4.0.02,8.03,7.06,11]tridecane-10,13-dione (“homosecohexaprismane-10,13-dione”, 8) has been prepared via a six-step sequence that results in homologation of two of the cyclopentane rings in pentacyclo[5.4.0.02,6.03,10.05,9]-undecane-8,11-dione, 1. The structure of 8 has been established unequivocally via single crystal X-ray structural analysis.