Oxiranes dialkyl

Dialkyl- und 2,3-Diaryl-oxirane bilden mit Natrium-cyclopentadienyl-dicarbonyl-eisen ein Alkanolat, das thermisch unter Inversion in ein trans- Aiken (>96°/od-Th ) zer-fallt3. Beim Behandeln des Alkanolats mit Tetrafluoroborsaure bzw. Hexafluorophos-phorsaure erhalt man einen Aiken-Komplex, der bei kurzzeitigem Erhitzen mit Jodid unter Erhalt der Konfiguration das c/.s-Aiken liefert4 ... 

A significant recent report of epoxides in reaction with anionic trivalent phosphorus is of general use for synthetic purposes. Dialkyl phosphite anions react with the less substituted oxirane carbon of arylsulfonyl epoxides to generate in good yield the corresponding 0-ketophosphonates (Equation 3.12).188... 

Deoxygenation of oxiranes with alkali 0,0-dialkyl phosphorotelluro-lates... 

Stable 2-metalo-l,3-dithianes, such as stannanes or silanes, have also been prepared and reacted with electrophiles. Sequential alkylation of a 2,2-bis-stannyl-l,3-dithiane (i, BuLi, oxirane ii, BuLi, alkyl bromide) furnished the 2,2-dialkylated products in 40% yield (Equation 40) <1997JA2058>. 

This topological rule readily explained the reaction product 211 (>90% stereoselectivity) of open-chain nitroolefins 209 with open-chain enamines 210. Seebach and Golinski have further pointed out that several condensation reactions can also be rationalized by using this approach (a) cyclopropane formation from olefin and carbene, (b) Wittig reaction with aldehydes yielding cis olefins, (c) trans-dialkyl oxirane from alkylidene triphenylarsane and aldehydes, (d) ketenes and cyclopentadiene 2+2-addition, le) (E)-silyl-nitronate and aldehydes, (f) syn and anti-Li and B-enolates of ketones, esters, amides and aldehydes, (g) Z-allylboranes and aldehydes, (h) E-alkyl-borane or E-allylchromium derivatives and aldehydes, (i) enamine from cyclohexanone and cinnamic aldehyde, (j) E-enamines and E-nitroolefins and finally, (k) enamines from cycloalkanones and styryl sulfone. 

The standard preparation of 2-oxazolidinones is by treatment of /3-amino alcohols with phosgene or its synthetic equivalents ethyl chloroformate, dialkyl carbonates or even urea (equation 174). Isocyanates react with oxiranes in the presence of amines to yield 2-oxazolidinones (equation 175) (79LA200). The action of isocyanates on cyclic carbonates results in 2-oxazolidinones (equation 176) and photolysis of alkyl azidoformates affords oxazolidinones via intermediate nitrenes (equation 177). 

Dialkyl vinylmethylidene tellurium compounds reacted with aliphatic and aromatic aldehydes to form dialkyl telluriums and a,/ -unsaturated oxiranes (cis/trans mixtures with the c/ i -isomer as the predominant component) in yields as high as 94%2. 

Various dialkyl- and diaryl(vinyl)sulfonium salts react with l//-indole-2-carbaldehyde in the presence of NaH to form a tetracyclic oxirane, for example, 167 these upon treatment with sodium azide form tricyclic azido alcohols analogous to compound 168 in 72% yield (Scheme 35) <1999T10659>. This annulation was a key step in total synthesis of Mitomycin K <1996TL6049>. 

The stereospecific transformation of oxiranes on exposure to organoaluminium amides under mild conditions has been described." " Isomerization of tram-epoxycyclododecane has been investigated with dialkylaluminium 7V,A -dialkyl-amides of various compositions (Eq. 116)." ... 

Cyclohexene oxide and its 3-hydroxy derivatives have been opened regio- and stereospecifically with phosphodiesters. The mechanism of the reaction of oxiranes with sodium dialkyl phosphite and diphenylphosphines has been studied. Cyclopropanecarboxylic acid derivatives have been obtained from substituted oxiranes with triethylphosphonoacetate anion.The mechanism of formation of isomeric alkoxyalkylacetates from oxiranes with alkyl halides and mercuric acetate has been discussed. ... 

Dialkylphosphite anions [(RO)2P(0)-], generated from dialkyl phosphites with KF, have been shown to combine with oxiranes to afford oc-hydroxyphosphonates <82S165, 84ZOB1205, 88ZOB2612, 90DOK(314)868). 

Dialkoxyphosphoryl-substituted carbanions, usually generated by the reaction of methyl-substituted phosphonic acid dialkyl esters with sodium hydride, react with a variety of oxiranes to give substituted cyclopropanes in moderate to good yield. Whereas the reaction of A5-phos-phanes with oxiranes (see Section 1.2.2.1.) gives cyclopropanes under forcing reaction conditions (200 °C, 8 hours), the phosphoryl-substituted carbanions give cyclopropanes under relatively mild conditions by a similar reaction mechanism (Houben-Weyl, Vol4/3, p 138). 

Alkyl-4,4-dimethyl- l,3-oxathiolan-3,3-dioxide werden pyrolytisch zu Aldehyden (Ausbeuten 94-100%)260, 2,2-Dialkyl-3-phenylsulfinyl-oxirane zu 2-Alkenalen261 gespalten ... 

The use of oxirane together with Na2HP03 to prepare (2-hydroxyethyl)phosphonic acid as its disodium salt is of historical interest. Other poorly exploited, yet interesting and potentially valuable, reactions include the combination of a trialkyl phosphite and dialkyl chlorophosphate with an oxirane to yield O-phosphorylated derivatives of (2-hydrox-yalkyl)phosphonic diesters (reaction 10)" and, following the initial reaction of an a,j8-unsaturated ketone with a phosphorus(III) triester to give the cyclic phosphorane 272, the subsequent further reaction of the latter with an aldehyde followed by hydrolysis (reaction 11)" Dialkyl acetyl phosphites are reported to react with oxirane through anionic intermediate species with the formation, albeit in low yields, of dialkyl (2-acetyloxyethyl)phos-phonates hydrolysable with concentrated HCl, to give (2-hydroxyethyl)phosphonic acid ... 

Oxirane rings also suffer rupture when acted upon by phosphorylcarbanions. The products are then dialkyl (3-hydroxyalkyl)phosphonates Reactions between dialkyl (lithiomethyl)phosphonate and a, -unsaturated aldehydes yields dialkyl (2-hydroxyalk-3-en-1 -yl)phosphonates. ... 

A synthesis of novel (1-amino-l-cyclopropyl)phosphonic acids is initiated by the ring opening of oxiranes by dialkyl (isocyanomethyl)phosphonate carbanions (Scheme 48). The product from the ring opening step is the (3-hydroxy-l-isocyanoalkyl)phosphonic diester 355, which, through its O-mesylate 356, is convertible into the cyclopropyl isocyanide 357 this, with HCl in MeOH, yields the racemic (1-amino-1-cyclopropyl)-phosphonic ester 358 ... 

In an approach to dialkyl esters of [ -hydroxy(heterocyclo)methyl]phosphonates, the oxiranes (308) were made to react with thiobenzamide to give the thiophen derivatives (309), and also with the pyridine or pyrimidine derivatives (310 X = CH, Y = C(COOEt) or N X = Y = N). For both systems, (309) and (311), subsequent... 

The structure of the final product has been verified by a combination of H, and NMR spectroscopy. The phosphorus chemical shift appears at 21.08 pp (R = CH3). The signal for the carbon atom bounded to the phosphorus appears at 50.70 ppm as a doublet with V(P,C) = 203.0 Hz (R = CH3). A two-step mechanism involving deprotonation of the dialkyl H-phosphonates by [Bu4NHC03 ], followed by nucleophihc attack of the dialkyl phosphonate anion (RO)2P(0) at the carbonyl group of the ketone, is presented. The oxirane formation during the second stage of the reaction involves displacement of the chloride ion. 

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