The alkaline hydrolysis of some cyclic phosphonium salts: ring-opening and ring-expansion reactions

1969 ◽  
pp. 252 ◽  
Author(s):  
David W. Allen ◽  
Ian T. Millar
Keyword(s):  
Alkaline Hydrolysis ◽  
Ring Opening ◽  
Ring Expansion ◽  
Phosphonium Salts ◽  
Hydrolysis Of

Arene chromium complexes with functionalized anellated rings. Selective formation of highly substituted polycycles

2002 ◽  
Vol 74 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Holger Butenschön
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Ring Expansion ◽  
Chromium Complexes ◽  
Ketone Group ◽  
Aldol Additions ◽  
Cope Rearrangements ◽  
Hydrolysis Of ◽  
Selective Formation ◽  
Tricarbonylchromium Complexes

Tricarbonylchromium complexes of benzocyclobutenone, benzocyclobutenedione, and 1,3-indandione are readily prepared by hydrolysis of the complexes of the corresponding acetals. Reduction of the benzocyclobutenone complex gives rise to an oxy-anion-driven ring opening to the corresponding ortho-quinodimethane intermediate, which can be trapped with dienophiles. Addition of 1-ethoxy-1-lithioethene allows a stereoselective ring expansion followed by an anionic ketol rearrangement with complete diastereoselectivity. Addition of 1-lithio-1-methoxyallene gives rise to a rare anionic 1-vinylcyclobutenol-cyclohexadienol rearrangement. Diaddition of alkenylmetal reagents at both keto groups in benzoyclobutenedione complexes causes dianionic oxy-Cope rearrangements to occur at ­78 °C, which are followed by diastereoselective intramolecular aldol additions. In some cases, a completely regioselective mono hydrolysis of di(enolates) was observed. Dianionic oxy-Cope rearrangements can also be realized with unstrained benzil derivatives giving 1,6-hexanediones and the corresponding aldol adducts. The 1,2,3-indantrione complex is obtained by oxidation of the 1,3-indandione complex with dimethyldioxirane in good yield and reacts with its central ketone group in hetero Diels­Alder cycloadditions.

Ring expansion in the alkaline hydrolysis of phosphetanium salts

1967 ◽  
pp. 1113 ◽  
Author(s):  
S. E. Fishwick ◽  
J. Flint ◽  
W. Hawes ◽  
S. Trippett
Keyword(s):  
Alkaline Hydrolysis ◽  
Ring Expansion ◽  
Hydrolysis Of

Phosphonium salts. I. The alkaline hydrolysis of some bis-phosphonium salts

1969 ◽  
Vol 22 (7) ◽  
pp. 1385 ◽  
Author(s):  
JJ Brophy ◽  
MJ Gallagher
Keyword(s):  
Kinetic Study ◽  
Phosphine Oxide ◽  
Alkaline Hydrolysis ◽  
Phosphorus Atom ◽  
Phosphonium Salt ◽  
P System ◽  
Phosphonium Salts ◽  
Partial Explanation ◽  
Reaction Proceeds ◽  
Hydrolysis Of

Ethane- and ethene-1,2-bisphosphonium salts are cleaved by alkali into a phosphine and a phosphine oxide with loss of the two-carbon bridge. When the phosphorus atom carries benzyl substituents, loss of the benzyl groups is competitive with loss of the bridge. ��� Based on a kinetic study, a synchronous mechanism, analogous to the alkaline hydrolysis of acyclic monophosphonium salts, is proposed to account for the fragmentation. ��� With 6-membered 1,4-diphosphonio heterocyclic salts the nature of the products is dependent on whether alkali or phosphonium salt is present in excess. With an excess of alkali a synchronous mechanism again appears to operate, while with an excess of salt the reaction proceeds stepwise and without loss of the bridge. A partial explanation of these facts is advanced in terms of non-bonded interactions in the intermediate phosphoranes. ��� The synchronous reaction appears to be favoured by coplanarity of the P-C-C-P system.

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