Rert 3-methyl-: 1-alkylation

For the other alkyl groups, hyperconjugation is diminished because the number of C—H bonds is diminished and in ferf-butyl there are none hence, with respect to this effect, methyl is the strongest electron donor and rert-butyl the weakest. 

Rates of radical additions to alkenes are controlled mainly by the enthalpy of the reaction, which is the origin of regioselectivity in additions to unsymmetrical systems, with polar effects superimposed when there is a favorable match between the electrophilic or nucleophilic character of the radical and that of the radico-phile. For example, in the addition of an alkyl radical to methyl acrylate (2), the nucleophilic alkyl radical interacts favorably with the resonance structure 3. Polar effects are apparent in the representative rate constants shown in Figure 4.14 for additions of carbon radicals to terminal alkenes. Addition of the electron-deficient or electrophilic rert-butoxycarbonylmethyl radical to the electron-deficient molecule methyl acrylate is 10 times as fast as addition of... 

The exceedingly bulky aluminum reagent aluminum tris(2,6-di-rert-butyl-4-methyl-phenoxide) (ATD) [140] was found to be superior to ATPH or MAD as a carbonyl protector in the alkylation of ynones [141]. Initial complexation of 3-octyn-2-one (13S) in toluene with ATD and subsequent addition of a hexane solution of BuLi at -78 °C generated 1,4 adduct 136 in 93 % yield together with a small amount of the 1,2 adduct (Sch. 103). 

Methylselenoxy analogs are even more difficult to react and treatment of the corresponding methylseleno derivative at 80 °C with terf-butyl hydroperoxide/basic alumina (conditions which proved particularly efficient for the synthesis of terminal olefins from methyl selenides bearing a methylseleno group at the terminus of the alkyl chain 7,8,12>, which are more difficult to react) as expected 140) does not lead 35) to the desired alkylidene cyclopropanes but to low yields of cyclobutanones resulting probably from the well-known 140) reaction of rert-butyl hydroperoxide with the alkylidene cyclopropane formed transiently35). 

II had an alkyl group of methyl, ethyl or rert-butyl (3 blend systems)... 

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