Direct C-Allylation of Aryl-Alkyl/Glycosyl Carbinols:  Facile Synthesis of C-linked Carbo-β²-/γ²-/δ²-Amino Acids

Abstract

A facile ZrCl4-catalyzed direct allylation of the p-methoxyphenyl-alkyl/glycosyl carbinols at room temperature, and the conversion of the derived aryl-glycosyl-alkenes into hitherto unknown C-linked carbo-beta2-/gamma2-/delta2-amino acids is reported.

1,2‐Diarylethanols by Alternative Regioselective Reductive Ring‐Opening of 2,3‐Diaryloxiranes

“…1‐(4‐Methoxyphenyl)‐2‐phenylethanol (2d) and 2‐(4‐Methoxyphenyl)‐1‐phenylethanol (3d): Alcohols 2d and 3d were obtained as a mixture in 95 % yield (96 mg from 100 mg of 1d ) by Pd/C catalytic hydrogenation and reduction with the [Cp 2 TiCl]/H 2 O system and in 75 % yield by reduction with the NaBH 4 /Pd system after chromatographic purification (petroleum ether/Et 2 O, 3:2). The 1 H NMR spectra were consistent with literature data 29 . 1 H NMR (500 MHz, CDCl 3 ): 87:13 mixture of 2d and 3d : δ = 1.85 (br.…”

Applications of Zirconium(IV) Chloride in Organic Synthesis

“…presence of various Lewis acid catalysts; the zirconium(IV) chloride catalyzed reaction gave 84% yield of product 10 (Scheme 5). 19 In 2006, Sharma et al 20 described the direct allylation of alkyl, aryl, and glycosyl 4-methoxyphenylcarbinols 11 in acetonitrile at room temperature catalyzed by 2 mol% zirconium(IV) chloride; this is a fascinating and ideal car-bon-carbon bond-forming protocol for the generation of functionalized olefins 12. This olefin was further converted into an amine and then subjected to oxidative cleavage of the aromatic ring to produce the unnatural amino acids 13 (Scheme 6).…”

Homogeneous Sc(OTf)3-Catalyzed Direct Allylation Reactions of General Alcohols with Allylsilanes

“…The same reaction proceeded smoothly with the use of a catalytic amount of HN(SO 2 F) 2 7 and I 2 /XB donor. 8 Besides, many Lewis acid-catalyzed direct allylation reactions of mainly secondary and tertiary benzylic alcohols with allylsilanes have been developed, in which InCl 3 , 9 InCl 3 /Me 3 SiX, 10 InBr 3 , 11 ZrCl 4 , 12 Ca(NTf 2 ) 2 /Bu 4 NBF 4 , 13 FeCl 3 ·6H 2 O in water, 14 BiCl 3 , 15 Bi(OTf) 3 in ionic liquid, 16 and solid acids such as H-montmorillonite, 17 Sn-montmorillonite, 18 and phosphomolybdic acid 19 are used as a catalyst. However, some of the reported reactions have several drawbacks such as variable yields, a prolonged reaction time from minutes to hours, the need for cooling (−78 °C) or heating (100 °C) under an inert atmosphere, difficult work up, stoichiometric or excess amount of some Lewis acids and Brønsted acids, and the formation of significant amounts of byproducts such as ethers through the intermolecular dehydration of benzylic alcohols.…”