Bicyclo octanone derivatives

Toda, F., Tanaka, K., Marks, D., and Goldberg, I. (1991) Optical Resolution of Bicyclo[2.2.1]heptanone, Bicyclo[2.2.2]octanone, and Bicyclo[3.2.1]octanone Derivatives by Inclusion Complexation with Optically Active Host Compounds, J. Org. Chem., 56, 7332-7335. 

Two groups have reported syntheses of the bicyclo[3.2.1]octane ring system found in certain tetracyclic diterpenes in which the key step is an intramolecular carbenoid insertion reaction. Thus decomposition of the diazoketone (4) in the presence of copper(II) sulfate gives the cyclopropyl ketone (5) in 48% yield. Acid hydrolysis of the acetal grouping is accompanied by concomitant fragmentation to the substituted bicyclo[3.2.1]octanone derivative (6).3... 

The conformational effects operative in the photochemistry of bicyclo-octanones (47) have been studied.48 The authors argue that several products should be possible if conformational effects control the fate of the biradicals formed by the Norrish Type I fission. However, if hydrogen abstraction is faster than conformational relaxation, the products must be derived from that conformation, e.g. (48), present immediately after bond fission. The results obtained... 

Inter molecular Additions to Cyclohexenones and Related Systems. Calculations have been reported that deal with a transition state analysis of the regioselectivity encountered in triplet-state (2 + 2)-cycloaddition reactions of cyclohex-2-enone. Diastereoselective (2 + 2)-cycloaddition of ethene to cyclohexenone carboxylates in the presence of chiral auxiliaries has been described. Yields of bicyclo[4.2.0]octanone derivatives can be obtained with de as high as 81%. The enone (16) can be tethered to a polymer substrate via the tether group R. Irradiation of this material in toluene with ethene at —78°C gives a 68% yield of the adduct (17). The de of the product is reasonable at 72%. Addition of 1,1-diethoxyethene to the cyclohexenone (18, R = Ph) results in the formation of the two stereoisomeric head-to-tail regioisomers (19) and (20). The outcome of the reaction is dependent on the rate of formation of 1,4-biradical intermediates. This can be seen in the dependence of the cisjtrans ratio on the solvent and on the temperature at which the reaction is carried out. Thus with enone (18, R = Ph) in acetone at 3°C, a cjt ratio of 4.4 is obtained, and this changes to 2.1 at —40°C. In acetonitrile the cjt ratio is only 1.9 at the same temperature. With the other derivative of (18), the cjt ratio is 1.3 in acetone and 0.8 in acetonitrile. Photoaddition of ethene to the enone carboxylate [21, R = (-)-8-(2-naphthyl)menthyl] results in the formation of the diastereoisomers (22) and (23) with a de of 56% at —78°C. The diastereo-selectivity can be enhanced by the addition of naphthalene derivatives to the solution. Thus with naphthalene, a de of 71% is obtained, and this can be increased to 83% with 1-phenylnaphthalene. ... 

A systematic investigation of cascading cyclic allylpalladation and Ac-Pd processes was carried out by Oppolzer who initially adapted the stoichiometric acylnickelation of Camps and Moreto to devise a Ni-catalyzed aUylmetallation-acylmetallation tandem cyclization to produce fused bicyclo[3.3.0]octanone derivatives.t i The scope of the cyclic allylmetallation-acylmetallation cascade was soon expanded by adaptation of the Pd-catalyzed Types I and II Ac-Pd processes developed systematically by Negishi (Sect. B). Specifically, the reactions shown in Scheme 25 were reported in 1989 by Yamamoto and co-workers as well as by Oppolzer and co-workers.t ... 

Diacetates of 1,4-butenediol derivatives are useful for double allylation to give cyclic compounds. l,4-Diacetoxy-2-butene (126) reacts with the cyclohexanone enamine 125 to give bicyclo[4.3.1]decenone (127) and vinylbicy-clo[3.2.1]octanone (128)[85,86]. The reaction of the 3-ketoglutarate 130 with cij-cyclopentene-3,5-diacetate (129) affords the furan derivative 131 [87]. The C- and 0-allylations of ambident lithium [(phenylsulfonyl)methylene]nitronate (132) with 129 give isoxazoline-2-oxide 133, which is converted into c -3-hydroxy-4-cyanocyclopentene (134)[S8]. Similarly, chiral m-3-amino-4-hyd-roxycyclopentene was prepared by the cyclization of yV-tosylcarbamate[89]. 

In an elegant new synthetic route to ( )-seychellene (610) cf. Vol. 4, p. 139 Vol. 5, p. 89), the bicyclo[2,2,2]octanone intermediate (608) is constructed by Diels-Alder reaction between a 2-silyloxydiene (607) and methyl vinyl ketone. Subsequent conversion of the product (608) into the seychellane framework involves intramolecular alkylation of the derived bromo-ketone (609) (Scheme 66). 

The chiral phosphonates 31a,e, possessing optically active BINOL as an auxiliary, also demonstrated their ability as asymmetric inducers in the dissymmetrization of carbonyl compounds. In order to achieve both high enantioselectivity and good chemical yield, addition of zinc chloride was quite effective in these transformations [8]. It is known that bicydo[3.3.0]octane derivatives usually adopt either W-, S-, or V-shaped conformations, and the observed stereochemistry of the alkene 92a was best explained by considering an initial approach of the nucleophile to the W-shaped bicyclo[3.3.0]octanone in the direction in which steric interaction between the reagent and the substrate is minimized. 

Most recently, oxa-di-Jt-methane rearrangement in aza-bicyclo[2.2.2]oct-2-en-5-one was explored this provides a novel route to pyrrozolidine alkaloids. Thus, sensitized irradiation of 126 and 128 furnished azabicyclo[3.3.0]octanones 127 and 129, respectively (Scheme 24). However, the derivatives 130 did not undergo the oxa-di-Jt-methane reaction. ... 

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