- Synthesis of carbocycles from ω-substituted α,β-unsaturated esters via radical-induced cyclizations
-
The intramolecular radical cyclization of ω-bromo α,β-unsaturated esters for the synthesis of carbocyclic compounds is described.The effect of carbon chain substituents, the bulk of the ester group, and the olefin geometry were examined.The highest level of stereoselectivity (trans/cis:9/1) was achieved with the Z ester via an exo cyclization.The sequential radical cyclization of a dihalodienoate to give a cis-fused bicyclic structure is also described.
- Hanessian, Stephen,Dhanoa, Daljit S.,Beaulieu, Pierre L.
-
p. 1859 - 1866
(2007/10/02)
-
- 127. Conformationally Controlled Odor Perception in 'Steroid-type' Scent Molecules
-
A series of compounds possessing a 'steroid-type' scent and related to 4-(4'-t-butylcyclohexyl)-4-methyl-2-pentanones (1 and 2) have been synthesized.The odor of these compounds has been found to be dependent on their conformation; only when the molecule can assume a steroid-like shape there is an interaction with the odor chemoreceptor.
- Ohloff, Guenther,Giersch, Wolfgang,Thommen, Walter,Willhalm, Bruno
-
p. 1343 - 1354
(2007/10/02)
-
- Stereochemistry of 1,4-Addition of Nucleophiles to Ethyl Cyclohexylidenecyanoacetates
-
The stereochemistry of 1,4-addition of several nucleophiles such as cyanide, sodium borohydride, and methylmagnesium iodide to three substituted ethyl cyclohexylidenecyanoacetates (1-3) has been determined.A higher preference for equatorial attack is observed in these compounds than in related cyclohexanones, which is considerably diminished by the use of aprotic polar solvents.The results do not show any appreciable contribution of product stability control, recently shown to be important for hydride reduction of cyclohexanones, and have been rationalized on thebasis of a six-center cyclic transition state in which steric factors play a dominant role.These compounds have also been reduced by catalytic hydrogenation (Pd/C), and, interestingly, with unhindered systems (1, 2) hydrogenation takes place more from the axial side (40-60percent) as compared to cyclohexanones.
- Nasipuri, Dhanonjoy,Sarkar, Ashis,Konar, Samir K.
-
p. 2840 - 2845
(2007/10/02)
-