Switching between Novel Samarium(II)-Mediated Cyclizations by a Simple Change in Alcohol Cosolvent

Abstract

Gamma,delta-unsaturated ketones undergo two very different stereoselective cyclization reactions mediated by samarium(II) iodide depending upon the alcohol cosolvent used in the reaction. Switching between an unprecedented aldol spirocyclization and a novel cyclobutanol-forming process can be achieved simply by changing the alcohol cosolvent from methanol to tert-butyl alcohol. [reaction: see text]

Three-dimensional printing with nano-enabled filaments releases polymer particles containing carbon nanotubes into air

“…All compounds were used as received and had the following purities: O‐tert‐butylhydroxylamine hydrochloride (TBOX, 99%), O‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA ≥ 98%), toluene (HPLC grade ≥ 99%), glyoxal (40 wt% in water), and methylglyoxal (40 wt% in water) were purchased from Sigma‐Aldrich/Fluka (St. Louis, MO). 4‐oxopentanal (4‐OPA, 98%) was synthesized by Richman Chemical Inc. (Lower Gwynedd, PA) as described previously . Formaldehyde (37% in water) was purchased from Ultra Scientific (N. Kingstown, RI).…”

SmI2-Mediated Carbonyl-Alkene Couplings for the Synthesis of Small Carbocyclic Rings

“…For example, lactone 56 underwent spirocyclization, followed by in situ lactone opening by the MeOH co-solvent to give ester 57 (R = Me) in 81% yield as a single diastereoisomer (Scheme 15, Table 2). 25 In order to prevent lactone ring opening during the course of the reaction, the employment of less nucleophilic alcohol co-solvents was investigated.…”

Development of an additive-controlled, SmI2-mediated stereoselective sequence: Telescoped spirocyclisation, lactone reduction and Peterson elimination

“…For example, complete diastereocontrol was achieved in the construction of cyclobutanols [13,17–22] and spirocyclopentanols (Scheme 1) [23–28]. The use of MeOH as an additive with SmI 2 was key to the success of these cyclisations [24]. …”