Dialkyl-1 -methylpiperidin

Acetoxy-l-acetylproline, 251 L-a-Amino-y-butyrolactone, 207 /-Butyl hydroperoxide-Dialkyl tar-trate-Titanium(IV) isopropoxide, 51 (Camphorylsulfonyl)oxaziridines, 64 Cumene hydroperoxide-Dialkyl tar-trate-Titanium(IV) isopropoxide, 52 Diisobutylaluminum hydride-Tin(II) chloride-(S)-1 -[ 1 -Methyl-2-pyrroii-dinyl]methylpiperidine, 116 (S)-Phenylglycine, 225 L-Valine, 226 Crown ethers Benzo-14-crown-4, 143 12-Crown-4, 167 12-Crown-6, 218... 

Cyanopiperidines are useful reagents that allow stereoselective alkylation at the 2-position and can be decya-nated with predictable outcomes. Alkylation of 2,4-/ra .r-iV-phenyl-2-cyano-4-methylpiperidine 268 results in formation of the 2,4-m-dialkyl product 269 (Scheme 65) <2002SL895>. A wide variety of alkyl halides can be employed... 

No comparison between trialkyloxonium fluoroborates and dialkyl sulfates has been made, but analysis of available data shows that oxonium salts are more generally applicable reagents for the preparation of lactim ethers. The alkylation of 3-carbethoxypiperid-2-one (7)25 and morpholin-3-one (8)32 with dimethyl sulfate failed, but with triethyloxonium fluoroborate these compounds gave 2-ethoxy-3-carbethoxy-3,4,5,6-tetrahydropyridine (9) and 3-ethoxy-3,4-dehydro-morpholine (10) in excellent yield. The selective character of triethyloxonium fluoroborate is shown in its reaction with 3,3-diethyl-5-methylpiperidine-2,4-dione (11 ).25 Reaction of 11 with the calculated quantity of dimethyl sulfate resulted in alkylation of the carbonyl group in position 4 with formation of 12, but reaction of 11 with triethyloxonium fluoroborate gave the lactim ether (13). 

Alkyl- and 2,6-dialkyl-piperidine alkaloids have been synthesized by the alkylation of cyclic a-ami-nonitriles such asN-benzyl-2-cyano-6-methylpiperidine or l-benzyl-2,6-dicyanopiperidine. 29... 

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