1, 4-Decalindione

Alcohol dehydrogenase-catalyzed reduction of ketones is a convenient method for the production of chiral alcohols. HLAD, the most thoroughly studied enzyme, has a broad substrate specificity and accommodates a variety of substrates (Table 11). It efficiendy reduces all simple four- to nine-membered cycHc ketones and also symmetrical and racemic cis- and trans-decalindiones (167). Asymmetric reduction of aUphatic acycHc ketones (C-4—C-10) (103,104) can be efficiendy achieved by alcohol dehydrogenase isolated from Thermoanaerohium hrockii (TBADH) (168). The enzyme is remarkably stable at temperatures up to 85°C and exhibits high tolerance toward organic solvents. Alcohol dehydrogenases from horse Hver and T. hrockii... 

Cotton effects of c/.t-decalones bearing no structural features which stabilize a particular conformer are likely to be due to contributions from both steroid-like and nonsteroid conformers. The absolute ring configurations of hydroxydecalones prepared by stereospecific HLAD catalyzed reductions of decalindiones follow from the measurement of the n-7t Cotton effect35 ... 

Generation of xanthyl cation from 2-(9-xanthyl)ethanol [87] is an extended Grob fragmentation. The intervening chain of separating the terminal donor groups may also incorporate heteroatoms, as shown in the deconvolution of a decalindione monoxime tosylate [88]. 

Intramolecular acylation (2, 35). The bridged decalindione (1) has been converted into 8-acetoxy-4-twistanone (2) in one step by treatment with boron trifluoride etherate, acetic acid, and acetic anhydride. The product is readily... 

Yordy and Reusch observed a similar intramolecular aldolization in a decalindione. As shown in equation (146), dione (125) is in equilibrium with aldol (126) under basic conditions (K = 2.3). Aldol (126) may be obtained as a crystalline substance, but it is easily converted back into dione (125) (e.g. under... 

This reaction can be used for synthesis of a decalindione such as 4 from 3, or for cyclization to cyclopentanones. 

Dodds, D.R. and Jones, J.B. (1988) Enzymes in organic synthesis 38. Preparations of enantiomericaDy pure chiral hydroxydecalones via stereospedfic horse liver alcohol dehydrogenase catalyzed reductions of decalindiones. 

In this section we must also mention the syntheses of cyclopentano-phenanthrene derivatives described in Scheme 88. These include, in the first place, attempts to apply the Robinson synthesis (Chapter II, Schemes 24 and 25) to the preparation of tetracyclic products with an angular methyl group at CiQ. By this method, for example, from the acetylmethylcyclo-hexene (63) and 1,5-decalindione (4) it was expected to obtain the diketone (65) through a sequence of Michael addition reactions and intramolecular crotonic condensation. However, it was found that the presence of the ce-methyl group in the acetylcyclene (63) suppressed the Michael reaction and... 

When 1,5-decalindione (4) is boiled with phenylhydrazine in acetic acid, in addition to other products, 6-aza-B-nor-D-homoequilenin derivatives (136) and (137) are formed [183]. 

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