- Palladium-Catalyzed Enantioselective Heteroarenyne Cycloisomerization Reaction
-
The extensively developed ene-type enantioselective cycloisomerization of classical 1,n-enynes provides an efficient approach to chiral cyclic 1,4-dienes. In contrast, the catalytic asymmetric heteroarenyne (heteroarene–alkyne) cycloisomerization involving the dearomative transformation of endocyclic aromatic C=C bonds remains unknown. Herein, we communicate a PdH-catalyzed enantioselective heteroarenyne cycloisomerization reaction of alkyne-tethered indole substrates (formal 1,5- and 1,6-enynes). Based on this strategy, a variety of structurally diverse chiral spiro and fused indoline derivatives bearing quaternary stereocenters and exocyclic C=C bonds are afforded in moderate to excellent yields and excellent enantioselectivities (up to 98 % ee). The classical ene-type enantioselective 1,5-enyne cycloisomerization of N-vinylpropiolamides is also developed to afford chiral 2-pyrrolones in good to excellent ee values.
- Liang, Ren-Xiao,Song, Ling-Jie,Lu, Jin-Bo,Xu, Wei-Yan,Ding, Chao,Jia, Yi-Xia
-
supporting information
p. 7412 - 7417
(2021/03/01)
-
- Flash Vacuum Pyrolysis of Stabilised Phosphorous Ylides. Part 4. Stepwise Construction of Terminal 1,3-Diynes, Conjugated Diacetylenic Esters and a Triacetylenic Ester
-
Thirteen examples of stabilised alkynol ylides 6 have been prepared and are found, upon flash vacuum pyrolysis (FVP) at 500 deg C, to undergo extrusion of Ph3PO to give the diacetylenic esters 7 in moderate yield.At 750 deg C the same ylides afforded terminal 1,3-diynes 8 although often in poor yield.For R = 2-MeSC6H4 both 7 and 8 undergo secondary loss of Me* and cyclisation to give 2-alkynylbenzothiophene derivatives 9 and 10 in low yield.The first example of an alkadiynol ylide 11 has been prepared and is converted by FVP at 500 deg C into the triacetylenic ester 12.
- Aitken, R. Alan,Seth, Shirley
-
p. 2461 - 2466
(2007/10/02)
-