Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• experimental steps, and the operations were troublesome. So an improved synthesis based on a self-protection strategy was designed and discussed. In this work, 3-O-ethyl-2,4-di-O-methylrhamnose was used as both the reaction substrate of C9–OH and the protecting group of C17–OH. The number of synthetic steps

• with different protecting groups, resulting in cumbersome steps and high costs. To reduce the synthetic steps and simplify the operations, we developed a new semi-synthesis of spinetoram J based on a self-protection strategy (Scheme 2). In this study, 3-O-ethyl-2,4-di-O-methylrhamnose was used not only

• sulfuric acid conditions, the 3-O-ethyl-2,4-di-O-methylrhamnose at the C17 position could be removed selectively under the weak acidic conditions to afford 5. The structure of compound 5 was also ascertained by NMR and mass spectrometry. Finally, compound 5 was glycosylated with donor 6 to provide

A semisynthesis of 3'-O-ethyl-5,6-dihydrospinosyn J based on the spinosyn A aglycone

• Kai Zhang,
• Shenglan Liu,
• Anjun Liu,
• Hongxin Chai,
• Jiarong Li and
• Lamusi A

Beilstein J. Org. Chem. 2017, 13, 2603–2609, doi:10.3762/bjoc.13.257

• , spinetoram is widely used in agriculture and food storage. This work reports a 7-step semisynthesis of 3'-O-ethyl-5,6-dihydrospinosyn J from spinosyn A aglycone. The C9–OH and C17–OH of the aglycone are successively connected to 3-O-ethyl-2,4-di-O-methylrhamnose and D-forosamine after selective protection

• and deprotection steps. Then, with 10% Pd/C as catalyst, the 5,6-double bond of the macrolide was selectively reduced to afford 3'-O-ethyl-5,6-dihydrospinosyn J. In addition, the 3-O-ethyl-2,4-di-O-methylrhamnose is synthesized from rhamnose which is available commercially, while the D-forosamine and

• opportunities to synthesize spinosyn analogues and rhamnose derivatives. Keywords: 3-O-ethyl-2,4-di-O-methylrhamnose; protecting groups; semisynthesis; spinetoram; spinosyn A; Introduction Spinosyns, a large family of secondary metabolites produced by aerobic fermentation of Saccharopolyspora spinosa, are a