Cyclopentene-, 3-acetoxy

The presence of the catalyst can also favor multiple Diels-Alder reactions of cycloalkenones. Two typical examples are reported in Schemes 3.6 and 3.7. When (E)-l-methoxy-1,3-butadiene (14) interacted with 2-cyclohexenone in the presence of Yb(fod)3 catalyst, a multiple Diels-Alder reaction occurred [21] and afforded a 1 1.5 mixture of the two tricyclic ketones 15 and 16 (Scheme 3.6). The sequence of events leading to the products includes the elimination of methanol from the primary cycloadduct to afford a bicyclic dienone that underwent a second cycloaddition. Similarly, 4-acetoxy-2-cyclopenten-l-one (17) (Scheme 3.7) has been shown to behave as a conjunctive reagent for a one-pot multiple Diels-Alder reaction with a variety of dienes under AICI3 catalysis, providing a mild and convenient methodology to synthesize hydrofluorenones [22]. The role of the Lewis acid is crucial to facilitate the elimination of acetic acid from the cycloadducts. The results of the reaction of 17 with diene... 

Although 1-vinylnaphthalene thermally reacts with 4-acetoxy-2-cyclopenten-1-one (98) to regioselectively afford 99, the isomer 2-vinylnaphthalene gives the same thermal cycloaddition with low yield (30 %) and reacts satisfactorily only with 98 at 10 kbar (Scheme 5.10). Both products 99 and 101 were converted into the cyclopenta[a]phenanthren-15-one (100) and cyclopenta[c]phenanthren-l-one (102) isomers. Acetoxyketone 98 acts as a synthetic equivalent of cyclo-pentadienone (114 in Scheme 5.14) in cycloaddition reactions [33]. 

Table 2. Percentages of Dibromocyclohexane 2h, Dibromocyclopentanone UHi, trans-1-Acetoxy-2-bromocyclohexane 2a, (OS=OAc) and trans-l-Acetoxy-2-bromo-cyclopentane 10a (OS=OAc) obtained from Solvolysis of 4 in HOAc containing 0.5 M Cyclopentene and Varying [Br ], n=0.1(LiC104), ... 

The stirred mixture of (15,41 )-ds -4-acetoxy-2-cyclopenten-l-ol (2) (5.0 g 35 mmol) and pyridine (4.18 g, 6.95 mmol) in dichloromethane (100 mL) is treated at 0°C with commercially available D3-acetyl chloride (3.44g 42mmol). The mixture is allowed to reach room temperature within 12 h and is then treated twice with 1M HC1 (50 mL), saturated aqueous NaHC03 and NaCl. The organic phase is dried over MgSC>4, the solvent is removed, and the crude product is purified by... 

ACETOXY-5-HYDROXYCYCLOPENT-1 -ENE, cis- 4-CYCLOPENTEN-1,3-DIOL, MONOACETATE, cis- (60410-18-6). 67,114 Acetoxylation, allylic, 68, 109... 

A. (4R)-(+)-Acetoxy-2-cyclopenten-l-one. A flame-dried, 2-L, three-necked, round-bcttomed flask, equipped with a Teflon-coated magnetic stirring bar, is purged with nitrogen and charged with 1.0 L of dry dichloromethane (Note 1), 1.5 g of anhydrous sodium acetate (Note 2), 70 g of 4 A molecular sieves (Note 3), and 23 g (162 mmol) of (1R,4S)-(+)-4-hydroxy-2-cyclopentenyl acetate (Note 4). Finely powdered pyridinium chlorochromate (50 g, 240 mmol) is added portionwise over a period of 5 min, and the mixture is stirred at room temperature for 3 hr (Note 5), then filtered through a pad of Florisil. The filtrate is concentrated on a rotary evaporator,... 

R, 3R )-3-Benzyloxycarbonyl-l -hydroxy- E21c, 3005 2-(Benzyloxy-methoxy)-l -oxo- E19d, 914 (SnR3 - Li/Cyclokond.) Cydopenten l-Acetoxy-4(bzw. 5)-(1 -cyclopenten yl-methyl)-3-oxo-EI5/1, 77 (Keton + R-COOH) Cydopropan... 

Acetoxy- A -steroid 3 -Acetoxy-A -steroid A -steroid (without C(3) substituent) S/i-Acetoxy-A -steroid 3 / Acetoxy- A -steroid 3 jS-Acetoxy- A < >-steroid A -Steroid Cyclopentene... 

Cyclopentadienone equivalents, such as 4-acetoxy-2-cyclopenten-l-one, below, may serve as conjunctive reagents for tandem Diels-Alder reactions providing polycyclic adducts." ... 

Acetoxy-2- (2-butenyl) - 5-carbethoxy - 3 -methyl - 2 - cyclopenten-l-one covered -with coned, aq. NH3, allowed to stand for 3 days with frequent shaking —> 2-(2-butenyl)-5-carbamyl-5-hydroxy-2-eyclopenten-l-one (Y 80%) boiled 1 hr. with 10% H2S04 2-(2-butenyl)-5-hydroxy-... 

The Bi2-catalyzed electrolysis of acetoxy bromo acetal 19a in DMF at -1.0 V alforded the diastereomeric acetal 20 as a product of a cyclization-elimination sequence. Starting from a chiral cyclopentene bromoacetal (19b) and l-octyn-3-one, a prostaglandin p2a precursor (21) containing all the structural features from C(, to C20 with SR, 11/ , and 12/ chirality, is obtained by the one-step formation of two carbon-carbon bonds in the B -catalyzed radical cyclization addition sequence (Scheme 7) [10]. 

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