Cyclopropane fused

Intramolecular Friedel-Crafts acylations of olefins also give cycHc a,P-unsaturated cycHc ketones. Cyclopropane fused bicyclo[5.3.0]octenones, thus obtained, were used in the preparation of the marine sesquiterpenes, africanol [53823-07-7] and dactjlol [58542-75-9] (174). 

Cyclopropane-fused chlorins are formed in good yields from copper porphyrins with ethyl diazoacetatc in benzene in the presence of copper(I) iodide.200,21 In the case of copper oc-taethylporphyrin 10, which gives a diastereomeric mixture of cyclopropane adducts 11, ethyl me o-porphyrincarboxylate 12 and a geminally dialkylated chlorin 13 (a rearrangement product of the cyclopropane chlorin 11) are observed as minor byproducts.200... 

Cyclopropane-fused chlorins derived from tetraphenylporphyrins can be prepared by the aforementioned carbene cycloaddition route, e.g. conjugative addition of nialonate to nickel(II) nitrotetraphenylporphyrin 14 (M = Ni) yields the cyclopropane-fused chlorin 15.22... 

An unusual rhodium-catalysed addition of a dienylboronate ester to highly strained alkenes, such as norbornene, has been reported, resulting in the formation of vinyl-cyclopropane-fused tricyclic products (Scheme 7). Preliminary mechanistic studies have been presented.246... 

As an extension of work on synthesis of strained cycloalkynes, trans- and tw-cyclopropane-fused medium ring (9-11-membered) cycloalkynes 108-111 and 113 were synthesized by thermolysis of 1,2,3-selenadiazoles 63, 105-107, and 112 with copper powder at 190-240 °C (Scheme 3) <1997LA1557>. /ra j-Bicyclo[7.1.0]dec-2-yne 108 is highly strained and has a low kinetic stability toward polymerization. Only traces of compound 108 were detected in the thermolysis of selenodiazole 63. The trapping with tetraphenylcyclopentadienone yielded an adduct 114 in 20% yield, whereas precursor 105 gave product 115 in 44% yield. 

Intramolecular cyclopropanation of allyl diazoacetates gives rise to interesting cyclopropane-fused y-butyrolactones. A chiral ruthenium bis(oxa-zolinyl)pyridine complex 85 was employed for the catalytic cyclization of trans-cinnamyl diazoacetate 83 at room temperature to obtain an optically active lactone 84 in 93% yield with 86% ee (Eq. 34, Fig. 2) [85]. Chiral porphyrin and salen complexes of ruthenium 86 [86] and 87 [87] also catalyzed the asymmetric intramolecular cyclopropanation of 83 to afford 84 in similar yields and enantiomeric excess. 

Dialkyl diazenedicarboxylates do not undergo efficient cycloaddition with vinyl ethers. For example the [2 -I- 2] adduct was obtained in low yield from the cyclopropane-fused dihydropy-ran 11 even at high temperature28. From the same substrate the [2 + 2] cycloadduct with 4-phenyl-3//-1,2,4-triazole-3,5(4//)-dione was obtained quantitatively even at low temperature through a polar mechanism involving an aziridinium imide as the intermediate28. 

On the other hand, the [4 +- 2] cycloaddition of diethyl diazenedicarboxylate and cyclic enol ethers is performed efficiently under UV irradiation. Without irradiation and by increasing concentration, the ene reaction product can be obtained from the substrates. The oxadiazine structure, as well as the stereochemistry of the cycloadduct 13 obtained from a cyclopropane-fused dihydrofuran and diethyl diazenedicarboxylate, was established by X-ray29. 

The or-analogue 159 has been made by a Pd-catalysed reaction involving an allylic phosphate as reactant, whilst others have also described routes to 159, its hydrogenated analogue, and the enantiomer and diastereoisomers of this, using enzymic desymmetrization to introduce chirality the products were evaluated for their ability to inhibit tumour necrosis factor-a. A chemo-enzymatic approach has also been used to make the cyclopropane-fused analogue 160 and... 

Table 9 was compiled from work on methyldecalin steroids , tetracyclic compounds, propellanes cyclopropane fused bicyclo[2,2.2]octanes , cyclopropanodecalins tricyclooctanes , homoadamantanes, 1,3-dehydroadamantanes , 2,4-dehydro-adamantanes and diamantanes. ... 

Structurally novel cyclopropane-fused cycloalkanes can be constructed by oligomerization of cyclopropenes. Cycloaddition across the double bond reduces ring strain in cyclopropenes enormously. When catalysed by transition metals, dimethyl-cyclopropene tri- or tetramerizes stereoselectively to novel polycycloalkanes (equation... 

Drawing on the development of the PK-type reaction of allenene derivatives, Mukai and co-workers reported the first total synthesis of the cyclopropane-fused tricyclic sesquiterpene 193 that was isolated from Jatropha neopauciflora (157). Treatment of the allenene precursor 191 (obtained from dimethyl D-tartrate) with... 

Alditols, Cyclitols and Derivatives Thereof,- Meso-D- /ycero-L-a/tro-heptitol and its monohydratc and hcptaacetate, meso-D- /ycero-L-ido-heptitol and its heptaacetate, i,3,4,5-tetra-0-benzyl-p-D-fhictopyranosyl cyanide, 34 le cyclopropane fused carbocyclic nucleoside analogue 63, neplanocin intermediatB 64,the cyclopentane 65, l,3,S,7-tetraoxadecalins 66 and 67... 

There are many examples of preparing cyclopentane structures from enynes by gold-catalyzed carbocyclization reactions. Toste et al. have reported that Au(l)-phosphine complexes act as superior catalysts for isomerization of 1,5-enynes to bicyclo[3.1.0]hexenes [124]. For example, treatment of 1,5-enyne (86) with 1 mol% of PhsP-AuPFfi in dichloromethane at room temperature results in formation of cyclopropane-fused cyclopentene (87) in 99% yield (Scheme 18.30). 1,6-Enynes also undergo similar cycloisomerization to five-membered cyclic compounds under the influence of cationic gold(l) catalysts [125, 126], Hydroxylated enynes are versatile precursors for cyclopentenones by gold-catalyzed cycloisomerization... 

Scheme 640 Synthesis of cyclopropane-fused linear triquinane.

Interestingly, reaction of zirconacyclopentadienes with a Simmons-Smith type of carbene reagent afforded zirconacyclopentene-cyclopropane fused intermediates 26, which reacted further with CO to generate 1,2,3,5-tetra-substitued benzenes 27 via a novel skeletal rearrangement, as shown in Scheme 11.11 [12],... 

The intramolecular cyclopropanation of nitroester 153 progressed in a stereoselective manner, and cyclopropane-fused lactone 154 served as a useful precursor for nitrocyclopropanes 155 (Scheme 1.73) [117]. The enantiomeric excess of fused-cyclopropane 154 exceeded 95% ee. Cyclopropanation was also possible using nitroacetate and PhI(OAc)2 [118]. 

Schiff-base-copper complex 244 catalyzed intramolecular cyclopropanation to give cyclopropane-fused lactone 245 (Scheme 1.114) [171]. Chiral Schiff base 246 was employed for asymmetric cyclopropanation of dienes (Scheme 1.115)... 

The allyl ester of acetylene carboxylate 341 was employed as a good precursor for the preparation of cyclopropane-fused 7-butyrolactones 342 (Scheme 1.165) [235]. The reaction progressed in the presence of catalytic amounts of Pd(0Ac>2 and stoichiometric amounts of an oxidant such as PhI(OAc>2. Palladium(ll) and palladium(lV) were presumed to be a catalytic cycle of the reaction. Amide derivative 343, which was readily prepared by the Ugi reaction, gave corresponding cyclopropane-fused 7-butyrolactam 344 in moderate yields (Scheme 1.166) [236]. 

Liron and Knochel reported the preparation of cyclopropane-fused indanes 359 from l-bromo-2-crotylbenzenes 358 in the presence of Pd(OAc)2. C—H activation progressed during the cyclopropane formation. l-Bromo-2-allyloxybenzenes 360 also underwent a similar reaction to give 361 in 77% yield [244]. 

Huang and Larock reported a similar cyclopropanation reaction to prepare cyclopropane-fused indole 362 (Scheme 1.173) [245], The initial phenyl palladium complex 363 rearranged to indole-palladium 364, which underwent the cyclopropanation reaction. 

When a small ring was fused to the bridge of TBP precursor 44a, strained cycloalkene would be formed in the rDA reaction. Thus, the rDA temperamre was expected to be raised in this case. Such precursors were prepared from cycloheptatriene 49e [55] and cyclooctatriene 49f [56]. The DA reaction of these diene equivalents with disulfonylethy-lene 4b proceeded via norcaradiene and bicyclo[4.2.0]octa-diene forms to give the tricyclo adducts 51e and 51f, which were transformed to precursors 53e-H2 and 53f-H2 in the usual manner (T. Okujima et al., manuscript in preparation). The rDA temperatures of 53e-H2 and 53f-H2 were proved to be extremely raised. Cyclopropane-fused 53e-H2 and cyclo-butane-fused 53f-H2 did not undergo the thermal rDA reaction below 265 and 180 C, respectively, and were successfully metallated with Cu(OAc>2 to give 53e-Cu and 53f-Cu (T. Okujima et al., manuscript in preparation). 

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