Synthesis of oxetane/azetidine containing spirocycles via the 1,3-dipolar cycloaddition reaction

EFFICIENT MULTIGRAM SYNTHESIS OF 3,3-Spiro-Α-Proline CONTAINING CHIMERAS

“…48 1,3-Dipolar cycloaddition seems to be the most attractive approaches existing so far. The method was elaborated and shared in the works by Jones et al 49 and Deng et al 50 Both studies lean on metal supported 1,3-dipolar cycloaddition reactions between ring-containing exocyclic alkenes as dipolarophiles and imines derived from -amino acid esters, thus affording spirocycles in 40-99% yield (Figure 2, D). Some available methods to the target compounds utilize a ready-made spirocyclic core rather than a(mono)cyclic precursors Thus, in the patent 51 carboxamide group was placed in 5azaspiro [2.4]heptane via organometallic mediated introduction of aldehyde followed by oxidation.…”

Oxetanes and Oxetenes: Fused-Ring Derivatives

“…This copper(I)-catalyzed process relies on a planar-chiral ferrocene P,N-ligand that allows for a perfect control of exo-selectivity and high enantiomeric excesses (94-99%) 99. Silver-catalyzed processes were also reported 100.…”

A Direct Synthesis of Highly Substituted π‐Rich Aromatic Heterocycles from Oxetanes

“…[6] In that time,the cost of key oxetanecontaining precursors has decreased dramatically,presumably because of increasingly favorable supply and demand consid-erations. Ther eady availability of ar ange of a,b-unsaturated carbonyl derivatives related to 1 by alkenylations of commercially available, inexpensive 3-oxetanone [8] prompted us to evaluate the generality of this transformation. Ther eady availability of ar ange of a,b-unsaturated carbonyl derivatives related to 1 by alkenylations of commercially available, inexpensive 3-oxetanone [8] prompted us to evaluate the generality of this transformation.…”

“…[7] In the course of ap roject to which the oxetane group was central, we observed afacile Lewis-acid-catalyzed rearrangement of oxetane-bearing enone 1 to disubstituted furan 2;t he starting material in this case is redox-equivalent to a1 ,4-dicarbonyl compound ( Figure 1B). Ther eady availability of ar ange of a,b-unsaturated carbonyl derivatives related to 1 by alkenylations of commercially available, inexpensive 3-oxetanone [8] prompted us to evaluate the generality of this transformation. [9] Given the many oxetane-ring opening reactions reported in the literature [10] we were surprised to discover that ageneral method to produce furans and pyrroles ( Figure 1C)f rom oxetane precursors had not been developed.…”