First total synthesis of kipukasin A

• Chuang Li,
• Haixin Ding,
• Zhizhong Ruan,
• Yirong Zhou and
• Qiang Xiao

Beilstein J. Org. Chem. 2017, 13, 855–862, doi:10.3762/bjoc.13.86

• subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity. Keywords: gold catalysis; kipukasin A; marine nucleoside; total synthesis; Vorbrüggen glycosylation

• ). Kipukasin A could be constructed by Vorbrüggen glycosylation [22][23] of a properly protected glycosyl donor 3 with uracil (4). Neighboring group participation of the 2’-O-acetyl group stereoselectively facilitate the β-glycosidic bond formation. Thus, the choice of a suitable protecting group at 5-OH

• position would be crucial for the success. It should fulfill at least two requirements: (1) it should be stable during the Vorbrüggen glycosylation; and (2) the deprotection process should be performed under very mild and neutral conditions without any influence on the 2’-O-acetyl group. At the same time

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

• Haixin Ding,
• Wei Li,
• Zhizhong Ruan,
• Ruchun Yang,
• Zhijie Mao,
• Qiang Xiao and
• Jun Wu

Beilstein J. Org. Chem. 2014, 10, 1681–1685, doi:10.3762/bjoc.10.176

• perbenzylated 1-O-methyl-5-deoxyribofuranose. The enzyme adenylate deaminase (EC 3.5.4.6) was successfully applied to the chemoenzymatic synthesis of trachycladines B. Keywords: marine nucleosides; natural products; total synthesis; trachycladines A and B; Vorbrüggen glycosylation; Introduction Marine

• ), nucleoside 3 could be synthesized by using 1,2,3,5-tetra-O-benzoyl-2-C-methyl-D-ribofuranose (5) as a carbohydrate acceptor by a Vorbrüggen glycosylation with the corresponding silylated nucleobases and a Lewis acid as a catalyst. As the key intermediate for the preparation of the anti-HCV nucleoside

• (unpublished results), the deoxygenation procedure of the C-5′ hydroxy group was accompanied by several undesired side reactions. Then we turned to synthetic route (B), which utilizes carbohydrate 4 as a Vorbrüggen glycosylation donor. Firstly, without the deoxygenation of the C-5′ hydroxy group at the late