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Acetals are one of the most frequently used protecting groups for aldehydes and ketones.1 Protic acids,2 Lewis acids,3 ion-exchange resins,4 and transition metal com-plexes5 have been utilized as the catalyst for the acetalization of carbonyl compounds. Many efficient procedures have been developed for the acetalization of saturated aldehydes and ketones.6 Few, however, are known for that of the ,/3-unsaturated ones.7 Moreover, available methods for the latter suffer from poor yield, tedious operation, or the use of expensive reagents. Early examples were reported by Fischer and Smith on the preparation of cyclic acrolein acetals.8 Heywood et al. employed p-toluenesulfonic acid as the catalyst and ethylene glycol as the acetalizing reagent in refluxing benzene to give the unsaturated acetals in low to moderate yields.9 1011Furfural was shown to react with ethylene glycol in the presence of aluminum chloride to generate the corresponding 1,3-dioxolane in good yield.1011 Noyori et al. reported the use of alkoxytrimethylsilane and trimethylsilyl trifluoromethanesulfonate (TMSOTf) in dichloromethane at -78 °C to afford the acetal of 2-cyclohexenone in high yield without any migration of the double bond.12 Hwu and co-workers carried out a comprehensive study on the acetalization of ,/3-unsaturated aldehydes employing Noyori's procedure.13 Conjugated (1) (a) Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.;

The phylogeny of subgenus Cyathophora and representatives of its closely related taxa within Allium were reconstructed based on nrDNA ITS and two plastid fragments (trnL-F and rpl32-trnL). The constructed phylogenies indicated that subgenus Cyathophora was not monophyletic and to be split in three parts positioned in different clusters. Allium kingdonii was unequivocally placed within subgenus Amerallium and formed an immediate sister relationship with New World Amerallium clade, suggesting an unexpected intercontinental disjunct distribution. For another, Allium trifurcatum was firmly nested within subgenus Butomissa next to A. tuberosum and A. ramosum, but it is distinctly different morphologically from the latter by thinly leathery bulb tunics, uniovulate locule and obviously 3-cleft stigma. Based on the geographic features, morphological and molecular evidences, two new sections, Kingdonia X.J.He et D.Q.Huang for A. kingdonii and Trifurcatum X.J.He et D.Q.Huang for A. trifurcatum, were proposed. The remaining three species of subgenus Cyathophora formed a well-defined clade, and the phylogenetic relationships among them recovered were consistent with previous findings. In addition, A. weschniakowii and A. subtilissimum were proven to be a member of subgenera Rhizirideum sensu stricto (s. str.) and Cepa, respectively, rather than subgenera Cepa and Polyprason previously proposed. Section Rhizomatosa represented by A. caespitosum should be subsumed within section Caespitosoprason of subgenus Rhizirideum s. str.