The synthesis of 2,3,5,6-endo,endo,endo,endo-tetrakis-substituted bicyclo[2.2.1]heptanes

Abstract

. Can. J. Chem. 59, 3365 (1981). Oxidation of the readily available diketone 2 affords high yields of the symmetrical dilactone 5, from which the all-endotetrakis(hydroxymethy1)norbornane 10 can be made. A related tetrol22 is also described. These tetrols are dehydrated to polycyclic di-ethers 12, 13, and 23 which constrain their oxygen atoms in rigid proximity within their structures. DOUGLAS N. BUTLER et TIMOTHY J. MUNSHAW. Can. J. Chem. 59,3365 (1981). L'oxydation de dicetone 2. que I'on peut obtenir facilement conduit avec d'excellents rendements a la dilactone symetrique 5 a partir de laquelle on peut preparer !e tetrakis (hydroxymethy!) norbonanes (10) completement endo. On decrit egalement le tetrol apparente (22). La deshydratation de tetrols conduit aux diethers polycycliques 12.13 et 23 dans lesquels les atomes d'oxygene sont maintenus dans un voisinage rigide a I'interieur de leurs structures.[Traduit par lc journal]The anticipated congestion of the endo face requires that any scheme directed toward the preparation of a 2,3,5,6-all-endo-tetrasubstituted norbornane must mark the prevention of epimerization of one (or more) of the substituents of any of the intermediates of the synthesis into the more stable exo stereochemistry. The caveat is successfully countered by using the readily available photo-cage 1 (1) from the cyclopentadienelbenzoquinone Diels-Alder adduct as the starting point of the synthesis only if the necessary carbon-carbon disconnections within 1 can be effected by processes which exclude any possibility of such an isomerization, preferably intramolecular events which maintain the all-endo stereochemistries until nonepimerizable functionalities are in place.A 2,3,5,6-tetrakis(hydroxymethy1) derivative of norbornane has been described (2), the origins of which suggest 2,3-endo,endo-5,6-exo,exo as the likely stereochemistry. The objective of this work was to prepare the all-endo isomer in order to study the chemical and physical consequences of the congestion imposed on the functionalities by this geometry. The dissolving-metal reduction (3) of the cage dione 1 required refluxing conditions (4) in our hands in order to produce 2. Curiously, very little chemistry has been described for this diketone, although it is easily prepared and ideal for the purpose at hand. Initially, we envisioned functionalizing the two methylene carbons a to the carbonyls as a logical strategy; however, selenium dioxide oxidation to the anticipated tetraketone 3 failed. A stereospecific bromination proceeded very efficiently to give a dibromide to which we ascribe the structure 4 from steric and spectroscopic rationalizations. The acetate and hydroxide anionic nuclieophiles did not change 4 under the conditions tried and a stronger base (methoxide) slowly produce a rearranged monobromoketo-ester of unknown structure (presumably via a Favorskii mechanism).Although unreactive to m-chloroperbenzoic acid, 2 reacted cleanly with trifluoroperacetic acid at room temperature to produce a mixture of dilactones. Fortuna...

Reactions of Cookson’s diketone with potassium halides in the polyphosphoric acid medium

“…Its physicochemical constants were in agreement with the literature data for tetracyclo[6.3.0.0. 4,11 .0 5,9 ]undecane-2,7-dione 8 [9]. Obviously, in this case reduction took place instead of the expected rearrangement to the D 3 -trishomocubane system (Scheme 2).…”

“…The rearrangement of C S -trishomocubane (pentacyclo[5.4.0.0 2,6 .0 3,10 .0 5,9 ]undecane) derivatives (1, Fig. 1) under acidic conditions is the most general approach for the synthesis of D 3 -trishomocubanes (2, Fig.…”

Design and Synthesis of Novel Propellanes by Using Claisen Rearrangement and Ring‐Closing Metathesis as the Key Steps

“…[2b] In connection with our interest in the preparation of annulated polyquinane we have prepared diallylated tetracyclic dione, 3,6-diallyltetracyclo[6.3.0.0 4,11 .0 5,9 ]undecan-2,7-dione (1) by using fragmentation methodology, which involves a fourstep sequence starting with 1,3-cyclopentadiene and 1,4-benzoquinone. [3][4][5] It was anticipated that the two allyl groups present in 1 would undergo ring-closing metathesis (RCM) to generate a new novel pentacyclic system 2 (Scheme 1).…”

“…[3][4][5] It was anticipated that the two allyl groups present in 1 would undergo ring-closing metathesis (RCM) to generate a new novel pentacyclic system 2 (Scheme 1).…”

An unusual rearrangement in the boron-trifluoride-promoted reaction of tetracyclo[6.3.0.04,11.05,9]undecane-2,7-dione monoethylene acetal with ethyl diazoacetate

“…As part of a program that involves the synthesis and chemistry of novel, substituted cage compounds (Marchand, 1988), the borontrifluoride-promoted reaction of tetracyclo-[6.3.0.04'1 ~.05'9]undecane-2,7-dione monoethylene acetal (1) with ethyl diazoacetate was studied. The starting material was synthesized by reacting tetracyclo[6.3.0.0a'~.05'9]undecane-2,7-dione (2) (Wenkert & Yoder, 1970;Butler & Munshaw, 1981), with one equivalent of ethylene glycol. The reaction was performed in refluxing benzene in the presence of a catalytic amount of p-toluenesulfonic acid.…”