Recent advances in synthetic facets of immensely reactive azetidines

Abstract

Recent developments in synthetic strategies towards functionalized azetidines along with their versatility as heterocyclic synthons.

β‐Lactam‐Synthon Interceded Diastereoselective Synthesis of 2‐Azido‐γ‐amino Alcohols with Subsequent Transformations to Functionally Enriched Heterocycles

“…Plausible mechanism for the synthesis of C-2 functionalized 2azido-g-amino alcohol 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 organic halides. [16] Most of the described methods suffer from several disadvantages including poor reactivity of bulky amines in ring opening reactions, poor diastereoselectivity, low yields, vigorous reaction conditions and use of toxic reagents. The synthesized g-amino alcohol was initially mesylated in the presence of triethylamine in dry chloroform at 0 O C to afford 3, which is a precursor for obtaining azetidines.…”

Synthesis of 2,3‐Fused Indoline Aminals via 4 + 2 Cycloaddition of NH‐free Benzazetidines with Indoles

“…Compound 3l was prepared in 58% yield following the general procedure as a yellow oil. 1 H NMR (400 MHz, Chloroform-d) δ: 7.07-6.88 (m, 4H), 6.72 (d, J = 7.6 Hz, 1H), 6.59 (m, 1H), 6.24 (d,J = 7.7 Hz,1H) 144.53,132.31,128.40 (q,J = 29.6 Hz),127.83,126.36,125.88,124.49,123.61,123.15,118.41,117.45,116.66 (q,J = 5.8 Hz),105.56,79.31,52.49,35.37,31.19,31.03,18.15,17.86;19 F NMR (376 MHz, 150.74,144.63,132.40,128.32 (q,J = 29.4 Hz),127.74,126.31,124.51 (q,J = 274.0 Hz),124.83,123.70,118.43,117.32,116.67 (q,J = 5.8 Hz),105.34,79.60,52.69,46.15,30.97,30.88,29.86,27.95,27.84,26.99,26.93,26.68;19 F NMR (376 MHz,…”

“…Compound 7 was obtained in 39% yield as a yellow oil. 1 H NMR (400 MHz, Chloroform-d) δ: 7.17-7.02 (m, 2H), 6.98 (dd, J = 7.3, 1.3 Hz, 1H), 6.87 (d, J = 8.5 Hz, 1H), 6.78 (dd, J = 6.6, 2.0 Hz, 2H), 6.75-6.61 (m, 3H), 6.51 (d,J = 7.7 Hz,1H) 148.45, 147.95, 142.21, 141.61, 136.98, 134.18, 127.87, 126.38, 121.77, 121.64, 120.03, 119.41, 118.58, 112.94, 112.74, 110.80, 107.83, 83.89, 56.04, 56.03, 39.86, 35.08, 32.25, 21.86…”

Titanium‐Mediated Synthesis of Spirocyclic NH‐Azetidines from Oxime Ethers

“…[6] Fore xample, NR-azetidines can be synthesized from 1,3-halo compounds or 1,3-diol derivatives by double alkylation of ap rimary amine (Sche- me 1A1). [6] Fore xample, NR-azetidines can be synthesized from 1,3-halo compounds or 1,3-diol derivatives by double alkylation of ap rimary amine (Sche- me 1A1).…”

“…Currently,many synthetic methods exist to access avariety of N-protected azetidine scaffolds. [6] Fore xample, NR-azetidines can be synthesized from 1,3-halo compounds or 1,3-diol derivatives by double alkylation of ap rimary amine (Sche-me 1A1). [7] Substituted azetidines can also be synthesized by various [2+ +2] cycloadditions,i ncluding the reaction of aldimines with ethyl 2,3-butadienoate under Lewis-basic conditions (Scheme 1A2).…”