111Several years ago we described the preparation of 1veratrylcarbonyl-l-azaspiro[4.5]decane (2) by the acidcatalyzed s piroa mi d a t i o n of N-[ 3-( 1-c y cl o h ex en-1-yl)propyl ] -2-(3,4-dimethoxyphenyl)acetamide (1) (2). We have utilized this process for the synthesis of the hitherto unreported 1,8-diazaspiro[4.5]decane system, which is the subject of this Note.
Treatment of 4(2-~arbamoylethyl)pyridine (3) (3) withbenzyl chloride gave quaternary salt 4 which was reduced with sodium borohydride to tetrahydropyridine 5 (4). Reduction of 5 with lithium aluminum hydride afforded amine 7 which was converted to amides 8a, 8b and 8c.Unlike neutral amide 1, which was cyclized readily to 2 by polyphosphoric acid a t 25", basic amides 8a, 8b and 8c were stable in this medium to 150"; at higher temperatures 8a, 8b and 8c were converted slowly to complex mixtures according to thin-layer chromatography. Like 1, neutral amides 9a and 9b, prepared by treatment of 8a and 8b with ethyl and methyl chloroformate (5), respectively, were cyclized smoothly to spiro[4.5]decanes 10a and lob.The spectral properties (see Experimental) of spiro-[4.5]decanes 10a and 10b were consistent with the structures assigned to these compounds by analogy with the transformation of I to 2.Cyclization of amide 5 with polyphosphoric acid at 145" afforded l-oxa-8-azaspiro[4.5] decane (6) (6), the infrared spectrum of which exhibited an intense absorption band at 1770 cm-' , characteristic of a y-lactone (7). C"2 I 3 CI-5
4‐(β‐Carbamoyläthyl)‐pyridin (I) liefert über das Salz (II) die Tetrahydroverbindung (III), die durch Polyphosphorsäure zum spirocyclischen Lacton (IV) cyclisiert wird.
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