Bicyclo octane-2,5-diones

The formation of bicyclo[3.3.0]octane-3,7-diones 3 by reaction of an a-diketone... 

Steven H. Ber z, James M. Cook, Ali Gawlsh, and Ulrich Weiss 27 CONDENSATION OF DIMETHYL 1,3-ACETONEDICARBOXYLATE WITH 1,2-DICARBONYL COMPOUNDS cis-BICYCLO[3.3.0]OCTANE-3,7-DIONES... 

Bicycloi3.3.0 octane-3,l-dione derivatives. The condensation of this reagent with 1,2-dicarbonyl compounds in an alkaline medium to give this ring system was reported some time ago1 and has since been explored in detail, mainly by Cook and Weiss.2 Detailed directions are now available for preparation of bicyclo[3.3.0]octane-3, 7-dione from glyoxal and that of the 1,5-dimethyl derivative from biacetyl (equation I).3 The condensation is applicable to a variety of diketones and yields are generally > 60%. It has been used for preparation of several natural products such as isocomene (2).4... 

Three tetracyclo[5.5.1.02,6.010,13]tridecanes are known at present. The reaction of glyoxal with dimethyl 3-ketoglutarate in aqueous solution at room temperature and pH 5 to give after treatment with acid c/,s-bicyclo[3.3.0]octane-3,7-dione has been discussed previously. More careful study of this condesation has led to the discovery that the two tetracyclic triketones 486 and 487 are also formed in low... 

An interesting new approach to monoterpene pyridine alkaloids has been described recently by Vidari and co-workers (206), based on the ability of a Schmidt reaction to desymmetrize bicyclo[3.3.0]octane-3,7-dione (249). This was achieved through reaction with sodium azide and boron trifluoride in CH2CI2 H20 (1 1) at 25°C for 3 h, which gave the lactam 250 in 25% yield. This could be increased to 50% yield by reacting 249 with sodium azide and cone. HC1. Ketalization followed by N-methylation with a phase transfer catalyst gave the lactam 251. Monomethylation of 251 afforded... 

Bicyclo[3.3.0 Joctane-3,7-dione has been prepared in five steps from dimethyl malonate and chloral in about 20% overall yield. The direct formation of bicyclo 3.3.0 )octane-3,7-diones by the 2 1 condensation of acetone-1,3-dicarboxyl ate and 1,2-dicarbonyl compound was discovered by Weiss and Edwards. The variation described in Part I has been optimized for large-scale preparation of the parent diketone. It is a good example of what Turner has called a "point reaction," as it is very sensitive to experimental details such as temperature and stirring rate. The aqueous buffer procedure given in. Part II is a "plateau reaction," and affords a general method for... 

Reaction of 1,2-dicarbonyl compounds with 3-oxoglutarates to yield c/5-bicyclo[3.3.0] octane-3,7-dione or [n.3.3]propellanedione (n > 2) tetracarboxylates. Subsequent acid-catalyzed hydrolysis and decarboxylation yield the respective 2,4,6,8-unsubstituted diones ... 

The reaction of dimethyl 3-oxoglutarate with glyoxal in aqueous acidic solution gives [3,3.0] octane, 3,7-dione-2,4,6,8-tetracarboxylate and on acid catalysed hydrolysis followed by decarboxylation it gives cis-bicyclo[3.3.0] octane-3,7-dione (Scheme 152). The reaction is believed to involve a double Knoevenagal reaction that gives an a,P-unsaturated y-hydroxycyclopentenone, which reacts with another molecule of dimethyl 3-oxoglutarate by Michael addition. 

---