shown by GLC analysis and 13C NMR to contain 5a (lo%), unknown compounds (12%), and 3a (78%). The data (GLC and '3c NMR) are identical with those from the products from reaction of 1 with methanol a t room temperature. Acknowledgment. We acknowledge grants from the Research Committee of the New Zealand Universities J. Org. Chem. 1990,55, 4144-4153 Grants Committee and helpful discussions with Professor M. A. Battiste.Supplementary Material Available: 13C and 'H NMR spectra for compounds 1,3a-d, 5a,b, 6a,b, 12,14a-c, 16a,b, and 18a,b (26 pages). Ordering information is given on any current masthead page.The carbenoid intermediate derived by treating ethyl 2-diazo-4-phthalimidobutyrate with rhodium(I1) octanoate undergoes transannular cyclization onto the adjacent imido carbonyl group. The resulting cyclic carbonyl ylide dipole was trapped with several dipolarophiles. In an attempt to prepare related substrates for cyclization studies, the reaction of ethyl lithiodiazoacetate with various aldehydes and ketones was studied. Treatment of the a-diazo-0-hydroxy ester derived from acetone or cyclopentanone with rhodium(I1) octanoate gave rise to a 0-keto ester. The exclusive phenyl shift encountered with acetophenone is in keeping with migration to an electron-deficient center. The reaction works well with acrolein, leading to high yields of 3-oxo-4-pentenoate. The 1,2-hydrogen shift pathway was found to proceed much faster than intramolecular cyclopropanation. Dehydration of the a-diazo-@-hydroxy esters generates vinyl diazo esters, which readily cyclize to lH-pyrazoles on thermolysis.

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NMR (CDC13, 250 MHz) d 2.66 ( 8 , 3 H), 7.2-8.0 (m, 10 H), 8.98 (d, J = 8 Hz, 2 H), 9.96 (s, 1 H).Pentaphen-5-01 Acetate (25). This compound was prepared from 0.75 g of 13a in the same manner as 24 except that the reaction with DMAD was carried out for 8 days. Small amounts of TCAA were added daily after 4 days. To the final reaction mixture was added 150 mL of water. The resulting precipitate was filtered, air-dried, and chromatographed on silica gel, eluting with toluene. Removal of the solvent from the appropriate fractions and recrystallization from toluene-hexane gave 25 in 22% yield, mp 185-187 "C: IR (Nujol) 1757 (C=O), 1206,1163, 1062, 873, 741 cm-'; 'H NMR (CDC13, 250 MHz) 6 2.65 (9, 3 H), 7.56-7.63 (m, 4 H), 7.63 and 7.70 (AB q, J = 9.5 Hz, 2 H, upfield portion obscured), 7.94-7.97 (m, 1 H), 8.01-8.05 (m, 1 H), 8.15-8.19 The scope of type I intramolecular [2 + 21 cycloadditions of alkenes with cY,/.%unsaturated ketenes (see eq 1) has been explored. These reactions generally produce bicyclo[3.2.0]heptan-6-ones containing an unsaturated substituent a t position 5. Ketenes 4, 7, 13, and 30 undergo the expected cycloaddition to give 6, 8, 14, and 31 in 5040% yield. Ketenes 10 and 16 undergo a 1,5-sigmatropic hydrogen shift to give dienals 11 and 17. Ketenes 23 and 24 undergo a reversible electrocyclic ring closure instead of a cycloaddition to give cyclobutenones 25 and 26. At higher temperatures electrocyclic ring closure is reversible and cyclobutenones 25 and 26 can be converted into 27 and 28 in 75% yield. Type I intramolecular cycloadditions cannot be used to produce bicyclooctanones such as 38. These vinyl cyclobutanones are versatile synthetic intermediates. Treatment of 32 with potassium hydride gives 34 and 35, suggesting that this approach will be useful for steroid synthesis. Treatment of 8 with boron trifluoride gives 39.

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