Mild and Highly Efficient Stereoselective Synthesis of 2,3‐Unsaturated Glycopyranosides using La(NO₃)₃ · 6H₂O as a Catalyst: Ferrier Rearrangement

Figures & data

short-legendScheme 1.

Scheme 2. Proposed mechanism

Table 1.  Synthesis of 2,3‐unsaturated glycopyranosides with 3,4,6‐tri‐O‐acetyl‐D‐glucal using La(NO₃)₃ · 6H₂O as a mild and efficient catalyst under solvent‐free conditions

Entry	Nucleophile	Product^a	Time (h)	Yield (%)^b	Ratio (α/β)^c
1			4	89	8∶2
2			4	86	9∶1
3			6	91	9∶1
4			4	94	9∶1
5			4	96	8∶2
6			4	96	9∶1
7			5	89	9∶1
8			8	86	9∶1
9			8	87	9∶1
10			8	79	8∶2
11			8	84	9∶1
12	C8H17SH		6	89	8∶2
13			4	94	8∶2
14			6	96	6∶4
^aAll the products given satisfactory analytical data.
^bIsolated yields after column chromatography.
^cRatio was determined on the basis of integration ratios of anomeric protons in its ^1H NMR spectrum.