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The stepwise synthesis of monodisperse polyethylene glycols (PEGs) and their derivatives usually involves using an acid-labile protecting group such as DMTr and coupling the two PEG moieties together under basic Williamson ether formation conditions. Using this approach, each elongation of PEG is achieved in three steps – deprotection, deprotonation and coupling – in two pots. Here, we report a more convenient approach for PEG synthesis featuring the use of a base-labile protecting group such as the phenethyl group. Using this approach, each elongation of PEG can be achieved in two steps – deprotection and coupling – in only one pot. The deprotonation step, and the isolation and purification of the intermediate product after deprotection using existing approaches are no longer needed when the one-pot approach is used. Because the stepwise PEG synthesis usually requires multiple PEG elongation cycles, the new PEG synthesis method is expected to significantly lower PEG synthesis cost.
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Picoloyl protecting group in synthesis: focus on a highly chemoselective catalytic removal
The picoloyl ester (Pico) has proven to be a versatile protecting group in carbohydrate chemistry. It can be used for the purpose of stereocontrolling glycosylations via an H-bond-mediated Aglycone Delivery (HAD) method. It can also be used as a temporary protecting group that can be efficiently introduced and chemoselectively cleaved in the presence of practically all other common protecting groups used in synthesis. Herein, we will describe a new method for rapid, catalytic, and highly chemoselective removal of the picoloyl group using inexpensive copper( ii ) or iron( iii ) salts.
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- Award ID(s):
- 1800350
- PAR ID:
- 10276708
- Date Published:
- Journal Name:
- Organic & Biomolecular Chemistry
- Volume:
- 18
- Issue:
- 25
- ISSN:
- 1477-0520
- Page Range / eLocation ID:
- 4863 to 4871
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0OB00803F
