title: Divergent Synthesis of α,γ-Disubstituted γ-Butyrolactones through Diastereoselective Bromolactonization with Alkali Metal Bromide: Asymmetric Total Synthesis of (+)-Dubiusamine C.
abstract: A divergent synthesis of α-substituted bromomethyl γ-lactones was developed, which involves the diastereoselective bromolactonization of α-substituted 4-pentenoic acids and 4-pentenamides via umpolung of bromide by use of alkali metal bromide and Oxone (potassium peroxymonosulfate mixture, 2KHSO5·KHSO4·K2SO4) to obtain mainly cis-products from α-substituted 4-pentenoic acids and trans-products from α-substituted 4-pentenamides, and it was found that the bromonium species generated from KBr and Oxone had higher activity than N-bromosuccinimide. Furthermore, the asymmetric total synthesis of (+)-dubiusamine C, which was isolated as a minor diastereomer from Pandanus dubius, was accomplished for the first time through the cis-selective bromolactonization of (S)-α-methyl-4-pentenoic acid in nine linear steps and 36% overall yield.
authors: Department of Chemistry, Graduate School of Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors: Katsuhiko
authors: K
authors: Moriyama
authors: Department of Chemistry, Graduate School of Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors: Toru
authors: T
authors: Sugiue
authors: Department of Chemistry, Graduate School of Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors: Chihiro
authors: C
authors: Nishinohara
authors: Department of Chemistry, Graduate School of Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors: Hideo
authors: H
authors: Togo
mesh_terms: D015107:4-Butyrolactone / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis / Q000737:chemistry*; D008672:Metals, Alkali / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010421:Pentanoic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D001965:Bromides; D007783:Lactones; D008672:Metals, Alkali; D010421:Pentanoic Acids; C000606029:dubiusamine C; C000606030:methyl-4-pentenoic acid; D015107:4-Butyrolactone