Bromides isopropenylmagnesium

Piers and co-workers (44) have reported that the cuprous chloride catalyzed 1,4-addition of isopropenylmagnesium bromide to the bicyclic enones 127 (R=H or CH3) gave exclusively the bicyclic ketones 128 (R=H or CH3) with the isopropenyl group axially oriented. Interestingly, with their trans ft/B ring junction, these enones are essentially conformationally rigid and their reactivity is in accord with the predictions made on the basis of stereo-electronic effects. 

Scheme 10 Kumada-Tamao-Corriu coupling of isopropenylmagnesium bromide with aryl bromides catalyzed by [Pd(IPr )(cin)CI] (42)...

Grignard reaction. Under catalysis by cuprous iodide, isopropenylmagnesium bromide effects efficient conjugate addition to cyclohexenone 2... 

Isopropenyl acetate, 191, 230, 309, 325 3-IsopropenylcycIohexanone, 92 Isopropenyllithium, 456 Isopropenylmagnesium bromide, 92 Isopropenyl methyl ether, 230-231 Isopropylamine, 44, 414 rw-4- 1 sopropylcyclohexane-1 -carboxylic acid, 412, 413... 

The tricyclo[4.3.1.03,7]decanol 38, an intermediate in the synthesis of ( )-9-isocyanop-upukeanane (39, isolated from the nudibranch Phyllidia varicasa and from its prey, a sponge, Hymeniacidon sp.) is synthesized by stereocontrolled addition of isopropenylmagnesium bromide to norbornenone derivative 34 and anionic oxy-Cope rearrangement of diol 35 as the key steps 1067. 

The diastereomeric mixture X, having a Cg sidechain, obtained by reaction of the preceding aldehyde with isopropenylmagnesium bromide was chain extended by the addic cayaiysed readion of heating with 2-methoxy-3-methylbuta-1,3-diene. However when exactly the same process was tried with compond Y, the... 

Tricyclic ketone 215 was converted by previously reported procedures to the ketoacid 218, which was treated with methylenetriphenylphosphorane to introduce the exocyclic methylene on the D ring (219) (Scheme 25). The ester was then converted to the aldehyde (220), treated with isopropenylmagnesium bromide to yield the allylic alcohol, subjected to Claisen rearrangement with methyl or thioacetate, and the resulting aldehyde converted to the tetramethyl allylic alcohol 208 by the previously described sequence (210 — 212, Scheme 24). The polyolefinic precursor to the serratene skeleton was obtained in overall yield of 3.1% from m-methoxycinnamic acid. 

Coriamycin (30) is a member of the picrotoxane sesquiterpenes it stimulates the central nervous system, similar to the activity of the better known picro-toxinin. In a general route for the construction of the picrotoxane carbon skeleton, Tanaka et al have described a stereocontrolled synthesis of (30), starting from the product (26) resulting from l,6>addition of 2-methylcyclopentane-l,3-dione to protoanemonin (25). Methanolysis of (26) led to (27), which was converted into (28) by addition of isopropenylmagnesium bromide. The latter was then converted into coriamycin (30) via the intermediate lactone (29). 

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