Intramolecular Hydrogen Bonds. X. Intramolecular Hydrogen Bonding in ω-N, N-Diethylaminoalkanols

Investigations on 1-azabicycles. 26*. IR spectra of the simplest pyrrolizidine alcohols in the region of the stretching vibrations of the hydroxyl group and their connection with the stereochemistry of the compounds

“…The value of ∆ν OH for the investigated pyrrolizidine alcohols is on the whole in good agreement with the corresponding values of ∆ν OH for ω-N,N-diethylaminoalkanols having a similar distance between the hydroxyl group and the tertiary nitrogen atom [10]. The values of ∆ν OH obtained by us for the unconjugated pyrrolizidine alcohols 1-5 are greater than the values of ∆ν OH for the corresponding acyclic analogs [10] by 10-20 cm -1 , and such a difference may be explained by the high basicity of the pyrrolizidines [19][20][21].…”

“…The correctness of the assignments made for the bands of the free and bonded hydroxyl groups was confirmed by the sizes of the differences of their maxima ∆ν OH = ν OH -ν' OH . For compounds 1 and 2 they were respectively 177 and 178 cm -1 , which is very close to the value ∆ν OH = 166-168 cm -1 for diethylaminoethanol [10], the open chain analog of compounds 1 and 2. The data of [10] were obtained using the same solvent, CCl 4 .…”

“…For compounds 1 and 2 they were respectively 177 and 178 cm -1 , which is very close to the value ∆ν OH = 166-168 cm -1 for diethylaminoethanol [10], the open chain analog of compounds 1 and 2. The data of [10] were obtained using the same solvent, CCl 4 . For all three compounds the tertiary nitrogen atom and the hydroxyl group are separated by a saturated chain with two carbon atoms.…”

“…Combination of the data on the weakly conjugated amino alcohols 6 and 8 and the strongly conjugated bases 7 and 9 (the type of conjugation of the bicycle is determined in accordance with [13,14]) enables new information to be obtained on conformational heterogenicity according to the type of coupling of the rings and the preferred conformational state of these substances. Based on the studies on cis-3,8-H-3-alkylpyrrolizidines [14][15][16][17] (10) [14,[16][17][18] it must be assumed that compounds 6-9 exist in the form of cis-(6-9 (A and C)) and trans-linked (6-9 (B and D)) conformations.…”

Efficient Synthesis of Six-Membered Ring D Analogues of the Pentacyclic Alkaloid Cephalotaxine by Two Palladium-Catalyzed Reactions

“…A solution of 5-chloropentan-1-ol [18] (10.0 g, 81.6 mmol) in THF (160 mL) was cooled to Ϫ78°C and methylmagnesium chloride (3.8  in THF, 21.5 mL, 81.6 mmol) was added dropwise. After the addition was complete, the solution was allowed to warm to room temperature.…”