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Nucleophilic substitution at a benzyl halide with valerolactone anion; 3-(4-nitrobenzyl)tetrahydro-2H-pyran-2-one

SyntheticPage 816
Submitted Dec 09, 2016, published May 16, 2017
kathryn allen (kathryn.allen@millersville.edu), Peter Sitarik (pjsitari@millersville.edu)
A contribution from Allen Group


			Reaction Scheme: <IMG src="/images/empty.gif"><IMG src="/images/empty.gif">Nucleophilic substitution at a benzyl halide with <SPAN id=csm1494929394644 class=csm-chemical-name title=valerolactone grpid="1">valerolactone</SPAN> anion<IMG src="/images/empty.gif"><IMG src="/images/empty.gif">

Chemicals Used

δ-Valerolactone (technical grade, distilled, dried with molecular sieves, stored cold, Sigma Aldrich)
Dimethylpyrimidinone (absolute, over molecular sieve, 1.5M in cyclohexane, 99.0%, Sigma Aldrich)
Lithium Diisopropyl Amide (1.5M in cyclohexane, Sigma Aldrich)
4-Nitrobenzyl Bromide (³97%, Alfa Aesar)
Tetrahydrofuran (anhydrous, ³99.9%, Sigma-Aldrich)
Ethyl Acetate (99%, Alfa Aesar)
Ammonium Chloride (Fisher Scientific)
Hexanes (VWR Analytical)
Dichloromethane (Reagent Grade, ³99.95%, PHARMCO-AAPER)

Procedure

A 500 mL, three-necked round bottom flask was purged with N2 and cooled to -78°C. Dry THF (50 mL) was cannulated into the flask, followed by addition of freshly distilled d-valerolactone (5 mL, 0.054mol). Slowly, and with stirring, LDA (13 mL, 0.059mol) was added. DMPU (39 mL, 0.323mol) was cannulated into the flask. After 1 hour, 4-nitrobenzylbromide (11.6 g, 0.054 mol) was added and the reaction was left for 4 hours at -78°C, then warmed to room temperature. The solution was quenched slowly with methanol and the product was extracted with EtOAc and washed with saturated NH4Cl solution. Rotary evaporation yielded a clumpy red precipitate. The crude product was dry-loaded onto silica gel and purified using column chromatography (1:3 DCM/hexanes to 100% DCM). The collected product was rotovapped down to a yellow solid, which was recrystallized from diethyl ether to yield an orange-yellow, pure product (9.7%). 

Author's Comments

The product was collected off the column with a 100% DCM wash after the yellow band (starting material) was collected. Theoretical uses are for ring-opening polymerization to form a new plastic that is potentially biodegradable, but tougher than unmodified polylactone.

Data

1H NMR (CDCl3, 400 MHz): δ 1.549 (1H, m), 1.87-1.96 (3H, m), 2.88-2.92 (2H, d), 3.39-3.43 (1H, d), 4.28-4.34 (2H, m), 7.39-7.41 (2H, d), 8.16-8.18 (2H, d).

13C NMR (CDCl3, 400 MHz): δ 21.92, 24.29, 36.94, 41.13, 68.49, 123.74, 130.10, 146.85, 173.30.

IR (cm-1): 1715 (C=O), 1512 (NO2), 1344 (NO2).

Melting Point: 116°C


Lead Reference

E. Kwan, J. Scheerer, D. Evans. The Stereochemical Course of Intramolecular Michael Reactions. Journal of Organic Chemistry. (78). 175-203. 2013

Other References

B. Parrish, J. Quansah, T. Emrick. Functional Polyesters Prepared by Polymerization of α-Ally(valerolactone) and It’s copolymerization with ε-Caprolactone and δ-Valerolactone. Journal of Polymer Science. (40). 1983-1990. 2002

Supplementary Information

 

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Get structure file (.cdx, .sk2, .mol)

Keywords: Lactone, nucleophilic, substitution

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