Frans-Decalone

In the following example a mixture of the cis- and frans-decalones is converted completely to the c/.v-isomer, in general the thermodynamically less favored isomer.10... 

This stereochemistry is similar to that in the reduction of a,/3-unsaturated ketones. Stork found that octalones like 7.88 were reduced exclusively to the frans-decalone 7.90, even in cases when the trans- was less stable than the corresponding c/.v-decalin. In this reaction, an electron is fed into the LUMO... 

It is noteworthy that reduction of the a,(3-unsaturated decalone shown below with lithium in liquid ammonia furnishes the fran -decalone as the major product in spite of the 1,3-diaxial interaction between the CH3-OCH3 substituents. ... 

Candelalide A was synthesized starting from frans-decalone 14 as shown in Scheme 11. Thus, the stereoselective reduction of the C3 carbonyl group in 14 with L-selectride produced the desired a-alcohol 44 in 91% yield as a single stereoisomer. After the hydroboration of 44 followed by the deprotection... 

In 2000, Solladie-Cavallo synthesized fluorinated ketones 408 from (+)-dihydrocarvone and investigated them in the asymmetric epoxidation of different fran -stilbenes and silyl enol ethers (Fig. 7.20) [285-287]. Later she reported rigid fran -decalones 409 which gave up to 70% ee (409a) and 20% ee (409b) in the epoxidation of ran -P-methylstyrene (Fig. 7.20) [288]. 

The 2(l)-enolate of frans-2-decalone is preferentially alkylated by an axial approach of the electrophile. 

A similar dissection of the excited states responsible for reaction by quenching has been carried out on cis- and /ra 5-8-methyl-1 -hydrindanone and cis- and frans-9-methyl-l-decalone with the purpose of determining the... 

The THF conditions were also used for alkylation of Awi0)-l-octalone (10). Some alkylation occurred at the 2-position, but the main products (62%) were cis-and frans-9-methyl-1 -decalone, (II) and (12). in the approximate ratio 3 1. 

The other alkanes were found to be much less reactive. Cyclohexane gave a cyclohexanol-one mixture, and adamantane was preferentially hydroxylated at the tertiary positions cis-decalin gave a mixture of cis- and frans-9-decanol (together with 1- and 2-decalones), suggesting the transient formation of radical carbon intermediates, which were also revealed by trapping experiments with CCI4. 

CycUzation of 4-bromobutyl-2electrochemical cleavage of the alkyl-cobalt bond in microemulsions and in DMF. Microemulsions gave a stereoselective ratio of 93 7 trans. cis, but poor stereoselectivity was obtained in homogeneous DMF. Preferential formation of thermodynamically favored trans-l-decalone involved equilibration of isomers via keto-enol tautomerism catalyzed by hydroxide ions formed by the coelectrolysis of water. 

When cis-2-decalone is dissolved in ether containing a trace of HCl, an equilibrium is established with frans-2-decalone.The latter ketone predominates in the equilibrium mixture. 

Ethylenedioxy-5,5,9 trimethyl-2-hydroxymethylene-frari5-l-decalone in dry acetone treated with anhydrous powdered K-carbonate and isopropyl iodide, then refluxed 6,6-ethylenedioxy-5,5,9-trimethyl-2-isopropoxymethylene-frans-1-decalone. Y 87%. R. F. Ghurch, R. E. Ireland, and J. A. Marshall, J. Org. Ghein. 27, 1118 (1962). 

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