Carbodiimide insertion into sulfonimides: one-step route to azepine derivatives via a two-atom saccharin ring expansion

2017 ◽  
Vol 53 (5) ◽  
pp. 901-904 ◽  
Author(s):  
Davin Tan ◽  
Tomislav Friščić
Keyword(s):  
Ring Expansion ◽  
Insertion Reaction ◽  
Direct Expansion ◽  
One Step

A novel carbodiimide insertion reaction enables a one-step, two-atom expansion of cyclic and linear sulfonimides, including the first direct expansion of saccharin into thiadiazepines.

The Reaction of 2-Hydro-2-oxo-5,6-benzo-l,3,2λ4-dioxaphosphorin-4-one with Imines and Carbonyl Compounds; Unusual Formation and First X-Ray Crystal Structure Determination of a Benzodioxaphosphepinone Ring System

1996 ◽  
Vol 51 (10) ◽  
pp. 1501-1510 ◽  
Author(s):  
Thomas Kaukorat ◽  
Ion Neda ◽  
Holger Thönnessen ◽  
Peter G. Jones ◽  
Reinhard Schmutzler
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Structure Determination ◽  
Ring Expansion ◽  
Ring System ◽  
Crystal Structure Determination ◽  
Insertion Reaction ◽  
X Ray ◽  
Ir Spectroscopic

On treatment of 2-hydro-2-oxo-5,6-benzo-1,3,2λ4-dioxaphosphorin-4-one (1) with the inline trimers trim ethyl- and tribenzyltriazine and the (monomeric) methylene-tert-butylimine, an insertion reaction of the imine molecule into the P-H bond of 1 took place, forming com pounds 2 -4 . Similar results were obtained when 1 was allowed to react with aldimines, asymmetric at carbon, leading to 5-7 . The diastereotopic properties of 5 - 7 were observed by 1H NMR spectroscopy. NMR and IR spectroscopic investigations on 5 - 7 indicated > C = O···H-N < interactions. Upon reaction of 1 with hexafluoroacetone, trifluoroacetophenone or phenyltrifluoromethylketimine, the derivatives 8 -1 0 , involving a P-O-C fragment, were obtained. The formation of the isomeric “alcohol form ”, bearing a P-C-OH fragment, could not be proved. In the reaction of 1 with various o-quinones. one of the oxygen atom s of the quinone was found to be bonded to phosphorus, whereas the hydrogen atom was found to migrate to the second oxygen atom . Upon reaction of 1 with chloral, an unusual ring expansion took place with formation of the benzodioxaphosphepinone (14). The reaction of 1 with other aldehydes could not be realized. In the reaction of 14 with triethylamine, the ammonium salt 15 was formed. For the first time, an X-ray crystal structure determination of a dioxaphosphepinone ring system was conducted; in 15 the seven-membered ring displays a pseudo tub conformation.

A silyl-mediated [3+2] photochemical cycloaddition

2006 ◽  
Vol 84 (10) ◽  
pp. 1259-1262 ◽  
Author(s):  
Michael G Organ ◽  
Debasis Mallik
Keyword(s):  
Ring Expansion ◽  
One Step

The generation of larger rings from intermediate cyclobutanes via a two-step [2+2] photocycloaddition – ring expansion, known as the de Mayo reaction, has been widely applied in synthesis. Herein a one-step synthesis of cyclopentanoids has been developed based on the photochemical irradiation of an enone in the presence of an allylsilane. The ability of the silyl moiety to stabilize the intermediate biradical is believed to be responsible for this unique transformation where one normally expects to see the [2+2] cyclobutane adduct.Key words: [2+2] photocycloaddition - ring expansion, allylsilanes, cyclopentanoids, photochemical.

One-step construction of complex polyheterocycles via a sequential post-GBB cyclization/spiro ring expansion triggered by a [1,5]-hydride shift

2018 ◽  
Vol 5 (10) ◽  
pp. 1628-1632 ◽  
Author(s):  
Sandip Gangadhar Balwe ◽  
Yeon Tae Jeong
Keyword(s):  
Ring Expansion ◽  
Hydride Shift ◽  
One Step

An efficient tandem route to novel amino-indazolo[3′,2′:2,3]imidazo[1,5-c]quinazolin-6(5H)-ones has been explored.

A Novel Access to Hydrindan Derivatives by Palladium Mediated Tandem Ring Expansion and Insertion Reaction of Alkenic Cyclobutanols

Synlett ◽  
1994 ◽  
Vol 1994 (08) ◽  
pp. 599-600 ◽  
Author(s):  
Hideo Nemoto ◽  
Motohiro Shiraki ◽  
Keiichiro Fukumoto
Keyword(s):  
Ring Expansion ◽  
Insertion Reaction

One-Step Conversion of Oxetane-Fused to 1,3-Oxazine-Fused Steroids

1998 ◽  
Vol 63 (10) ◽  
pp. 1613-1622 ◽  
Author(s):  
Andrea Hajnal ◽  
János Wölfling ◽  
Gyula Schneider
Keyword(s):  
Diethyl Ether ◽  
Ring Expansion ◽  
Aryl Nitriles ◽  
One Step ◽  
Ring Expansion Reaction ◽  
Ether Complex

In a ring-expansion reaction, alkyl and aryl nitriles, in the presence of tetrafluoroboric acid-diethyl ether complex, react with 3-methoxy-16β,17β-dihydro-4'H-oxeto[3',2':16,17]estra-1,3,5(10)-triene to give 3-methoxy-16β,17β-dihydro-4'H-[1,3]-oxazino[5',6':16,17]estra-1,3,5(10)-triene derivatives. Under similar conditions 3-methoxy-16α,17α-dihydro-4'H-oxeto[3',2':16,17]estra-1,3,5(10)-triene undergoes a Wagner-Meerwein rearrangement.

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