Ethyl iodide stereochemistry

The 2-ethyl derivative was obtained in 18% yield when perhydropyr-ido[l,2-6][l,2]thiazine-l,1-dioxide was treated with Na in boiling toluene, and then with ethyl iodide at 60-70°C (62AP615). The stereochemistry of the product was not investigated. 

Desethyl-3-oxovincadifformine (276) has been synthesized126 by appropriate modification of Levy s route to 3-oxovincadifformine alkylation of (276) by means of LDA and ethyl iodide then gave 3-oxopseudovincadifformine (277), of undetermined stereochemistry. 

Electrophilic attack on the sulfur atom of thiiranes by alkyl halides does not give thiiranium salts but rather products derived from attack of the halide ion on the intermediate cyclic salt (B-81MI50602). Treatment of a s-2,3-dimethylthiirane with methyl iodide yields cis-2-butene by two possible mechanisms (Scheme 31). A stereoselective isomerization of alkenes is accomplished by conversion to a thiirane of opposite stereochemistry followed by desulfurization by methyl iodide (75TL2709). Treatment of thiiranes with alkyl chlorides and bromides gives 2-chloro- or 2-bromo-ethyl sulfides (Scheme 32). Intramolecular alkylation of the sulfur atom of a thiirane may occur if the geometry is favorable the intermediate sulfonium ions are unstable to nucleophilic attack and rearrangement may occur (Scheme 33). 

Unsuccessful couplings arose when resin-bound olefin was reacted with aryl triflates (presumably reflecting the lower reactivity observed in solution) and also when resin-bound iodide was reacted with ethyl propionate, where polymerized products were observed. Interestingly, attempts at transesterification as a means to release the products were unsuccessful. The stereochemistry (i.e., cis/trans) of the products was not addressed. 

Naito has also described analogous tandem radical addition-cyclization processes under iodine atom-transfer reaction conditions [16,32], Treatment of 186 with z-PrI (30 eq.) and triethylborane (3x3 eq.) in toluene at 100 °C gave, after cleavage from the resin, the desired lactam product 190 in 69% yield (Scheme 46). Similar reactions involving cyclohexyl iodide, cyclopentyl iodide, and butyl iodide were also reported as well as the reaction with ethyl radical from triethylborane [16,32], The relative stereochemistry of the products was not discussed. 

Kanetsuna and Nonaka [264,370] compared the stereochemistry of diethyl 2,3-diphenylsuccinate formed in the oxidation of (1) ethyl phenylacetate (in the presence of iodide ion), (2) its sodium salt, and (3) ethyl phenylmalonate [Eq. (58)]. A phenylethox-... 

Support for this view comes from their work on the stereochemistry of 1.6-addition (catalyzed by cupric acetate) of methyl-, ethyl-, isopropyl-, and -butylmagnesium halides on dienone 237 93% of the axial isomer 139 was obtained with CH3MgI, 98% with C2H5MgBr and 100% with (083)2 CHMgBr and (CH3)3CMgCl. Campbell and Babcock (49) have also studied the cuprous catalyzed reaction of methylmagnesium iodide with various steroidal 4,6-dien-3-ones. They found axially substituted C-7 methyl derivatives as the predominant 1,6-adducts. 

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