Hept-2-enonate

Tetra-O-acetyl-2,3-dideoxy-D-ara6mo-hept-2-enonic acid, T-33... 

Starting from optically active 1-chlorovinyl p-tolyl sulfoxide derived from 2-cyclohex-enone, the asymmetric synthesis of cyclopropane derivative (85) was realized (equation 23) . Addition reaction of lithium enolate of tert-butyl acetate to 83 gave the adduct (84) in 96% yield with over 99% ee. Treatment of the latter with i-PrMgCl in a similar way as described above afforded optically pure (15,6/ )-bicyclo[4.1.0]hept-2-ene (85) in 90% yield. 

Fig. 3 The anomalous ORD spectrum consisting of several overlapping Cotton bands of the unsaturated rigid ketone, bicyclo(2,2,l)hept-5-enone, which shows how complex the spectrum can be, even for a single molecule.

Cycloheptadienes, and derivatives thereof, have been made by solvolysis of tosyl and 4-ni-trobenzyl esters of bicyclo[4.1.0]hept-2-en-5-ol and related compounds. These reactions, which were designed to give mechanistic information, produced complex product mixtures which were not synthetically useful. 4,4-Dimethyl-6-methoxybicyclo[4.1.0]heptan-entfo-2-ol (11) was cleaved by dilute hydrochloric acid to yield 3,3-dimethylcyclohept-5-enone (12) quantitatively. ... 

Enynes in which three or four atoms separate the double and triple bonds cyclize upon complexation to Co2(CO)g and subsequent heating to give bicyclic enones (equation 52). With the exception of slightly elevated temperatures the conditions required are no different than those of the stoichiometric procedure described earlier for reactive substrates in intermolecular Pauson-Khand reactions. The intramolecular cycloaddition cannot in general be carried out under catalytic conditions. Hex-l-en-5-yne, which would give a four-membered ring upon intramolecular cycloaddition, instead undergoes alkyne trimerization exclusively.3 The most extensively studied systems are those derived from hept-l-en-6-yne, as the products, bicyclo[3.3.0]oct-l-en-3-ones, are useful in the synthesis of numerous cyclopentane-based polycy-clics. 

A review of formal aza-Diels-Alder reactions of imines with e-rich dienes and enones, in the presence of Lewis acids/Brpnsted acids/organocatalysts, has been presented. Bifunctional A-acyl aminophosphine catalysts (75) are effective asymmetric organocatalysts in the hetero-4- -2-cycloaddition of a-substituted allenoates with tosylaldimines to produce optically active tetrahydropyridines. The Brpnsted acid-catalysed aza-Diels-Alder reactions of cyclopentadiene with iminoacetates possessing two chiral auxiliaries yielded 2-azabicyclo[2.2.1]hept-5-ene cycloadducts with high exo-selectivities. ... 

The nickel-iminophosphine-catalysed 4- -2-cycloaddition of enones with allenes formed highly substituted dihydropyrans. The enantioselective amine-catalysed 4-I-2-cycloaddition of allenoates with oxo-dienes produced polysubstituted dihydropyrans in high yields and with high enantioselectivities. Novel enam-ine/metal Lewis acid bifunctional catalysis has been used in the asymmetric inverse-electron-demand hetero-Diels—Alder reactions of cyclic ketones with Q ,j9-unsaturated a-ketoesters. The 4- -2-cycloaddition of acylketenes (80) with 2-unsubstituted and 2-monosubstituted 3-aryl-2//-azirines (81) produced 1 1 (82) or 2 1 (83) adducts, being derivatives of 5-oxa-l-azabicyclo[4.1.0]hept-3-ene or 5,7-dioxa-l-azabicyclo[4.4.1]undeca-3,8-diene. The formation of the monoadducts proceeds via a stepwise non-pericyclic mechanism (Scheme 25). A-heterocyclic carbene-catalysed 4- -2-cycloaddition of ketenes with 1-azadienes yielded optically active 3,4-dihydropyrimidin-2-ones (93% ee) ... 

Siloxy enones result from ring opening bicyclo[2.2.1]hept-S-enyl ethyl ketone and arc used in the synthesis of hydroxymethyl decalins. while obtusenyne substitution uses siloxy intermediates. Siloxy sustituted starting materials and products are reported for a wide... 

In strongly acidic media, bicyclo[3,2,0]heptan-6-one and bicyclo[3,2,0]hept-2-en-7-one undergo clean isomerization to form protonated cyclohept-2-enone and cyclohepta-2,4-dienone, res pectively. ... 

Bicyclo[3,2,0]heptan-6-ones and bicyclo[3,2,0]hept-2-en-7-ones are cleanly iso-merized to cyclohept-2-enones and cyclohepta-2,4-dienones, respectively, in strong acids such as FSO3H and 96% H2SO4, e.g. (174) -> (175), and a useful method of converting phenols into cycloheptane derivatives of type (176) is by flash vacuum pyrolysis of their propiolate esters. Mixtures of isomeric cycloheptadienols are produced when the epoxide resulting from addition of dimethylsulphonium methyl-ide to acylvinyIcyclopropane is heated at 180 °C for 12 h. ... 

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