Metal-catalyzed double migratory cascade reactions of propargylic esters and phosphates

Abstract

Propargylic esters and phosphates are easily accessible substrates, which exhibit rich and tunable reactivities in the presence of transition metal catalysts. π-Acidic metals, mostly gold and platinum salts, activate these substrates for an initial 1,2- or 1,3-acyloxy and phosphatyloxy migration process to form reactive intermediates. These intermediates are able to undergo further cascade reactions leading to a variety of diverse structures. This tutorial review systematically introduces the double migratory reactions of propargylic esters and phosphates as a novel synthetic method, in which further cascade reaction of the reactive intermediate is accompanied by a second migration of a different group, thus offering a rapid route to a wide range of functionalized products. The serendipitous observations, as well as designed approaches involving the double migratory cascade reactions, will be discussed with emphasis placed on the mechanistic aspects and the synthetic utilities of the obtained products.

Scheme 1

Competitive 1,2- or 1,3-migration of propargylic esters and phosphates

Scheme 2

Double migratory cascade reactions of propargylic esters and phosphates.

Scheme 3

Gold-catalyzed 1,3-OAC/1,2-H migration cascade towards cyclopentenone.

Scheme 4

Competitive 1,2-H shift versus cyclopropanation.

Scheme 5

Gold-catalyzed 1,3-OAC/1,2-H migration cascade for the synthesis of bicyclo[3.1.0]hexenes.

Scheme 6

Further reactions of propargylic acetates.

Scheme 7

Platinum-catalyzed 1,3-OCOR/1,2-H migration cascade towards tetracyclic 2,3-indoline-fused cyclopentenes.

Scheme 8

Toward the synthesis of the tetracyclic core of vindolinine.

Scheme 9

Copper-catalyzed 1,3-OP(O)(OEt)₂/1,2-H migration cascade towards heterocycles.

Scheme 10

Cycloisomerization of a labeled phosphatyloxy alkynyl pyridine.

Scheme 11

Kumada cross-coupling of obtained phosphatyloxy-containing hetrocycles.

Scheme 12

Alternative pathways for 1,2 hydrogen shifts to metal carbenes.

Scheme 13

Metal-catalyzed 1,3-OAc/1,5-H migration cascade for the synthesis of polycyclic compounds.

Scheme 14

Gold-catalyzed 1,3-OXO/1,2-alkyl migration cascade towards dienes and naphthalenes.^,

Scheme 15

Proposed mechanism for the gold-catalyzed 1,3-OXO/1,2-alkyl migration cascade. ^,

Scheme 16

Gold-catalyzed 1,3-OAc migration/ring expansion cascade.

Scheme 17

Further insight into the mechanism of gold-catalyzed 1,3-OAc migration/ring expansion cascade.

Scheme 18

Gold-catalyzed enantioselective 1,3-OPiv/1,3-alkyl migration cascade.

Scheme 19

Gold-catalyzed 1,3-OCOR/1,3-acyl migration cascade.

Scheme 20

Gold-catalyzed 1,3-OAc/1,5-acyl migration cascade.

Scheme 21

Mechanism of gold-catalyzed 1,3-OAc/1,5-acyl migration cascade supported by DFT calculations.

Scheme 22

Intramolecular [4+2] cycloaddition of obtained dienes.

Scheme 23

Stereocontrolled gold- and copper-catalyzed 1,3- OP(O)(OEt)₂/1,3-halogen migration towards dienes.

Scheme 24

Mechanism of the stereodivergent reaction.

Scheme 25

Selective transformations of an obtained product.

Scheme 26

Gold-catalyzed 1,2-OPiv/1,2-H migration cascade for synthesis of 1,3-dienes.

Scheme 27

One-pot Au-catalyzed diene formation/Diels-Alder reaction sequence of propargylic pivalates.

Scheme 28

Pt-catalyzed 1,2-OAc/1,2-H migration cascade for synthesis of 1,3-dienes.

Scheme 29

Gold-catalyzed 1,2-OAc/1,4-allyl migration cascade.^–

Scheme 30

Employment of propargylic thioester in gold-catalyzed double migration.^,

Scheme 31

Enantioselective gold-catalyzed 1,2-OPiv/1,4-allyl migration cascade.

Scheme 32

Mechanistic studies of the second migration process.

Scheme 33

Stereocontrolled double 1,2-acyloxy migration cascades.^,

Scheme 34

Mechanism of double 1,2-acyloxy migration.

Scheme 35

Synthetic utilities of obtained 2,3-bis-acetoxy-1,3-dienes.