Iron-catalysed allylation–hydrogenation sequences as masked alkyl–alkyl cross-couplings

Abstract

An iron-catalysed allylation of organomagnesium reagents (alkyl, aryl) with simple allyl acetates proceeds under mild conditions (Fe(OAc)2 or Fe(acac)2, Et2O, r.t.) to furnish various alkene and styrene derivatives.

A One‐Pot Synthesis of α,β‐Unsaturated Esters From Esters

“…Colorless liquid; 1 H NMR (400 MHz, CDCl 3 ) δ 7.63 (d, 1H), 7.47 (dz, 2H), 6.88 (d, 2H), 6.32 (d, 1H), 4.24 (q, 2H), 3.83 (s, 3H), 1.33 (t, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ 167.5, 161.4, 144.3, 129.8, 127.3, 115.8, 114.4, 60.4, 55.5, 14.5. NMR data were in accordance with reported literature 15 …”

Synthesis of Plakortolides E and I Enabled by Base Metal Catalysis

“…This drawback was circumvented by in situ desilylation with TBAF in the presence of TFE (2,2,2-trifluoroethanol) to buffer the enolate resulting from the oxa-Michael reaction, thereby avoiding potential Weitz-Scheffer-type epoxidation. 14 This tandem endoperoxide formation afforded (-)plakortolide I (2) in 42% yield, along with its C6-epimer (+)-plakortolide E (1) in 35% yield. Single crystals of 1 were grown and analyzed by X-ray analysis, thereby confirming the structure and absolute configuration of 1 and indirectly of 2 (Scheme 4).…”

“…Unfortunately, Mukaiyama-Isayama hydroperoxidation of 3 with Et3SiH and Co(thd)2 in vigorously oxygen saturated 1,2-DCE at ambient temperature resulted in no conversion even at prolonged reaction time or elevated temperature. 14 However, addition of protic solvents such as i-PrOH facilitated the conversion. Under these conditions, the direct formation of endoperoxides 1 and 2 was observed, but was accompanied by decomposition of the products resulting in low isolated yields.…”

“…13 Alkene 3 was prepared in analogy to a procedure by JACOBI VON WANGELIN et al for the iron-catalyzed alkylation of allyl acetates with alkylmagnesium compounds. 14 A Schlenk tube was charged with anhydrous Fe(OAc)2 (4.9 mg, 28 μmol, 10 mol%) and anhydrous LiCl (16.6 mg, 392 μmol, 1.4 equiv) and flame-dried under high vacuum until bubbling ceased. Then a solution of allyl acetate 4 (58.8 mg, 280 μmol, 1.0 equiv) in THF (1.3 mL) was added and the resulting mixture was cooled to 0 °C.…”

“…11,12 In 2002, Jung reported the first synthesis of racemic plakortolide I (2). 13 Ten years later, Vatèle 14 described an asymmetric synthesis of the (-)-plakortolide I (2) and (+)-plakortolide E (1).…”