J. Chem. Soc. Perkin Trans. 1 1997 3129 Triphenylphosphine promoted addition of dimethyl acetylenedicarboxylate to 1,2-benzoquinones facile synthesis of novel ldquor;-spirolactones Vijay Nair,*,a J. Somarajan Nair,a A. U. Vinod a and Nigam P. Rath b a Organic Chemistry Division Regional Research Laboratory (CSIR) Trivandrum-695 019 India b Department of Chemistry University of Missouri St. Louis MO 63121 USA The addition of dimethyl acetylenedicarboxylate to oquinones in the presence of triphenylphosphine leading to highly functionalised ldquor;-spirolactones is reported. Introduction The stoichiometric as well as the catalytic use of phosphines and a variety of other organophosphorus compounds has become an integral part of organic synthesis.1 In particular triphenylphosphine (TPP) acts as a catalyst in various isomerization reactions of alkynes and allenes,2 and in the nucleophilic addition of malonate to methyl propiolate.3 The addition of TPP to electron deficient alkynes leading to zwitterionic compounds and the subsequent reactions of the latter species notably dimerization has been known from the work of Tebby and co-workers.4 Very recently dimethyl acetylenedicarboxylate (DMAD) has been reported to add to activated carbonyl compounds such as a-keto esters and a-keto nitriles under the influence of TPP to afford g-lactones.5,dagger; In view of our general interest in the chemistry of o-quinones,6 we have examined the reaction of DMAD with o-quinones in the presence of TPP and our preliminary results are reported here.Results and discussion A mixture of 3,5-di-tert-butyl-1,2-benzoquinone 1 and DMAD when treated with 50 mol of TPP at 80 8C in benzene for 24 h afforded 48 of the spirolactone 1a (Scheme 1).The structure of the spirolactone 1a was confirmed on the basis of spectral and analytical data and finally by X-ray crystallography (Fig. 1).Dagger; The spirolactone formation can be rationalized as shown in Scheme 2. Similar results were obtained with a number of other oquinones and these are summarised in Table 1. Scheme 1 O O O CO2Me OMe O O CO2Me CO2Me PPh3 1a 1 48 80 deg;C Benzene 50 mol + dagger; The addition of DMAD to benzaldehyde in the presence of triphenylphosphine leading to the formation of g-butyrolactone in low yield was known from an earlier report.7 Dagger; Atomic coordinates thermal parameters and bond lengths and angles have been deposited at the Cambridge Crystallographic Data Centre (CCDC).See instructions for Authors J. Chem. Soc. Perkin Trans. 1 1997 Issue 1. Any request to the CCDC for this material should quote the full literature citation and the reference number 207/149. Conclusion In conclusion we have found that the reaction of o-quinones with DMAD in the presence of TPP leads to a facile synthesis of highly functionalized spirolactones. Experimental All reactions were carried out in oven dried glassware at 110 8C. Silica gel chromatography was carried out using 100ndash;200 mesh silica gel. Melting points were taken in a Toshniwal melting Fig. 1 X-Ray crystal structure of 1a Scheme 2 CO2Me CO2Me O O R R Ph3P CO2 Me MeO2C R O O R CO2Me PPh3 O MeO O R R CO2Me PPh3 O MeO O O R R O O O OMe O R R O O OMe O OMe R = But ndash;OMe Ph3P PPh3 1a PPh3 + + + + + ndash; ndash; ndash; ndash; 3130 J.Chem. Soc. Perkin Trans. 1 1997 Table 1 Reaction of various quinones with dimethyl acetylenedicarboxylate Entry 2 3 4 5 Quinone O O O O But But O O OMe O O But Conditions Benzene 80 8C 1 h Benzene 80 8C 5 h Benzene 80 8C 4 h Benzene 80 8C 8 h Product(s) O O CO2Me OMe O O O MeO2C MeO O O CO2Me OMe O But But OMe O O CO2Me OMe O O But O O CO2Me OMe O O CO2Me OMe But O O (1:1) 5b 5a 4a 3b 3a 2a + + Yield () a 75 26 b 70 46 a Isolated yield. b Inseparable mixture. point apparatus and are uncorrected. Light petroleum refers to the fraction boiling in the range 60ndash;80 8C. IR spectra were recorded on a Perkin-Elmer 882 spectrometer. 1H NMR spectra were recorded on a Varian Unity 500 NMR spectrometer at 500 MHz and JEOL EX-90 at 90 MHz with tetramethylsilane as internal standard.J Values are given in Hz. 13C NMR spectra were recorded at 125 MHz (Varian Unity 500) and 22.5 MHz (JEOL EX-90). Mass spectra were recorded in AE1 MS-50-(IE) and elemental analyses were obtained on a Perkin-Elmer elemental analyser-2400. General procedure Methyl 3,5-di-tert-butyl-59,6-dioxo-49-methoxyspirocyclohexa- 2,4-diene-1,29-(29,59-dihydrofuran)-39-carboxylate. A mixture of 3,5-di-tert-butyl-1,2-benzoquinone 1 (0.440 g 2.0 mmol) and dimethyl acetylenedicarboxylate (0.320 g 2.2 mmol) was purged with argon at 80 8C in benzene (10 ml). To this mixture triphenylphosphine (0.262 g 1.0 mmol) was added and the heating continued for 24 h. The solvent was removed under vacuum and the residue chromatographed on silica gel and the product eluted with an 80 20 light petroleumndash;ethyl acetate mixture to afford the spirolactone 1a (0.340 g 48 60 based on reacted quinone); mp 130ndash;132 8C (CH2Cl2ndash;hexane) (Found C 65.92; H 7.22; M1 362.C20H26O6 requires C 66.28; H 7.25; M 362); nmax/cm21 2968 2880 1779 (COO lactone) 1738 (CO2Me) 1684 1660 (C CCO); dH(500 MHz; CDCl3) 6.978ndash;6.974 (d 1H J 2.0 C CH) 5.644ndash;5.640 (d 1H J 2.0 C CH) 4.281 (s 3H C COMe) 3.643 (s 3H CO2Me) 1.228 (s 9H But) 1.147 (s 9H But); dC(125 MHz; CDCl3) 192.114 166.624 160.923 149.503 147.889 144.575 135.959 122.781 80.306 60.338 51.927 35.137 35.001 29.257 28.527. X-ray analysis of 1a The crystal used for X-ray study had dimensions of 0.4 times; 0.4 times; 0.35 mm. Crystal data C20H26O6 M = 362.41 triclinic space group P1� unit cell dimensions a = 9.3827(7) Aring; b = 9.7857(7) Aring; c = 12.3881(7) Aring; a = 97.993(5)8 b = 93.180(6)8 g = 116.531(5)8 V = 998.85(12) Aring;3 DC = 1.205 Mg m23 T = 298(2) K R indices I 2s(I) = R1 = 0.0496 wR2 = 0.1366; number of unique reflections = 3421 l = 1.54178 Aring;.Data collection and processing. The intensities were measured on a Siemens P4 X-ray diffractometer using Cu-Ka radiation and 2qndash;w. Of the 7387 reflections collected 3421 with I 2s(I) were used for structure determination and refinement. Acknowledgements J. S. N. thanks RRL and CSIR for a research fellowship. A. U. V. thanks the American Cyanamid Co. USA for financial assistance. The authors thank Dr Sasi Kumar ICSN CNRS France and Dr Jessy Mathew Molecumetics Washington USA for high resolution NMR spectra and elemental analyses. References 1 Organic Phosphorus Compounds ed.G. M. Kosolopoff and L. Maier Wiley 1973 New York. 2 B. M. Trost and U. Kasmeir J. Am. Chem. Soc. 1992 114 7933. 3 B. M. Trost J. A. Martinez R. J. Kulawiec and A. F. Indolesa J. Am. Chem. Soc. 1993 115 10 402. 4 (a) M. A. Shaw J. C. Tebby R. S. Ward and D. H. Williams J. Chem. Soc. (C) 1968 1609; (b) P. J. Butterfields and J. C. Tebby J. Chem. Soc. Perkin Trans. 1 1979 1189; (c) J. C. Tebby and I. F. Wilson J. Chem. Soc. Perkin Trans. 1 1979 2133. 5 K. Nozaki N. Sato K. Ikeda and H. Takaya J. Org. Chem. 1996 61 4516. 6 V. Nair and S. Kumar Synlett 1996 1143 and references cited therein. 7 E. Winterfeldt and H.-J. Dillinger Chem. Ber. 1966 99 1558. Paper 7/06272I Received 27th August 1997 Accepted 1st September 1997 J. Chem. Soc. Perkin Trans. 1 1997 3129 Triphenylphosphine promoted addition of dimethyl acetylenedicarboxylate to 1,2-benzoquinones facile synthesis of novel ldquor;-spirolactones Vijay Nair,*,a J.Somarajan Nair,a A. U. Vinod a and Nigam P. Rath b a Organic Chemistry Division Regional Research Laboratory (CSIR) Trivandrum-695 019 India b Department of Chemistry University of Missouri St. Louis MO 63121 USA The addition of dimethyl acetylenedicarboxylate to oquinones in the presence of triphenylphosphine leading to highly functionalised ldquor;-spirolactones is reported. Introduction The stoichiometric as well as the catalytic use of phosphines and a variety of other organophosphorus compounds has become an integral part of organic synthesis.1 In particular triphenylphosphine (TPP) acts as a catalyst in various isomerization reactions of alkynes and allenes,2 and in the nucleophilic addition of malonate to methyl propiola.3 The addition of TPP to electron deficient alkynes leading to zwitterionic compounds and the subsequent reactions of the latter species notably dimerization has been known from the work of Tebby and co-workers.4 Very recently dimethyl acetylenedicarboxylate (DMAD) has been reported to add to activated carbonyl compounds such as a-keto esters and a-keto nitriles under the influence of TPP to afford g-lactones.5,dagger; In view of our general interest in the chemistry of o-quinones,6 we have examined the reaction of DMAD with o-quinones in the presence of TPP and our preliminary results are reported here.Results and discussion A mixture of 3,5-di-tert-butyl-1,2-benzoquinone 1 and DMAD when treated with 50 mol of TPP at 80 8C in benzene for 24 h afforded 48 of the spirolactone 1a (Scheme 1).The structure of the spirolactone 1a was confirmed on the basis of spectral and analytical data and finally by X-ray crystallography (Fig. 1).Dagger; The spirolactone formation can be rationalized as shown in Scheme 2. Similar results were obtained with a number of other oquinones and these are summarised in Table 1. Scheme 1 O O O CO2Me OMe O O CO2Me CO2Me PPh3 1a 1 48 80 deg;C Benzene 50 mol + dagger; The addition of DMAD to benzaldehyde in the presence of triphenylphosphine leading to the formation of g-butyrolactone in low yield was known from an earlier report.7 Dagger; Atomic coordinates thermal parameters and bond lengths and angles have been deposited at the Cambridge Crystallographic Data Centre (CCDC).See instructions for Authors J. Chem. Soc. Perkin Trans. 1 1997 Issue 1. Any request to the CCDC for this material should quote the full literature citation and the reference number 207/149. Conclusion In conclusion we have found that the reaction of o-quinones with DMAD in the presence of TPP leads to a facile synthesis of highly functionalized spirolactones. Experimental All reactions were carried out in oven dried glassware at 110 8C. Silica gel chromatography was carried out using 100ndash;200 mesh silica gel. Melting points were taken in a Toshniwal melting Fig. 1 X-Ray crystal structure of 1a Scheme 2 CO2Me CO2Me O O R R Ph3P CO2 Me MeO2C R O O R CO2Me PPh3 O MeO O R R CO2Me PPh3 O MeO O O R R O O O OMe O R R O O OMe O OMe R = But ndash;OMe Ph3P PPh3 1a PPh3 + + + + + ndash; ndash; ndash; ndash; 3130 J.Chem. Soc. Perkin Trans. 1 1997 Table 1 Reaction of various quinones with dimethyl acetylenedicarboxylate Entry 2 3 4 5 Quinone O O O O But But O O OMe O O But Conditions Benzene 80 8C 1 h Benzene 80 8C 5 h Benzene 80 8C 4 h Benzene 80 8C 8 h Product(s) O O CO2Me OMe O O O MeO2C MeO O O CO2Me OMe O But But OMe O O CO2Me OMe O O But O O CO2Me OMe O O CO2Me OMe But O O (1:1) 5b 5a 4a 3b 3a 2a + + Yield () a 75 26 b 70 46 a Isolated yield. b Inseparable mixture. point apparatus and are uncorrected. Light petroleum refers to the fraction boiling in the range 60ndash;80 8C. IR spectra were recorded on a Perkin-Elmer 882 spectrometer. 1H NMR spectra were recorded on a Varian Unity 500 NMR spectrometer at 500 MHz and JEOL EX-90 at 90 MHz with tetramethylsilane as internal standard.J Values are given in Hz. 13C NMR spectra were recorded at 125 MHz (Varian Unity 500) and 22.5 MHz (JEOL EX-90). Mass spectra were recorded in AE1 MS-50-(IE) and elemental analyses were obtained on a Perkin-Elmer elemental analyser-2400. General procedure Methyl 3,5-di-tert-butyl-59,6-dioxo-49-methoxyspirocyclohexa- 2,4-diene-1,29-(29,59-dihydrofuran)-39-carboxylate. A mixture of 3,5-di-tert-butyl-1,2-benzoquinone 1 (0.440 g 2.0 mmol) and dimethyl acetylenedicarboxylate (0.320 g 2.2 mmol) was purged with argon at 80 8C in benzene (10 ml). To this mixture triphenylphosphine (0.262 g 1.0 mmol) was added and the heating continued for 24 h. The solvent was removed under vacuum and the residue chromatographed on silica gel and the product eluted with an 80 20 light petroleumndash;ethyl acetate mixture to afford the spirolactone 1a (0.340 g 48 60 based on reacted quinone); mp 130ndash;132 8C (CH2Cl2ndash;hexane) (Found C 65.92; H 7.22; M1 362.C20H26O6 requires C 66.28; H 7.25; M 362); nmax/cm21 2968 2880 1779 (COO lactone) 1738 (CO2Me) 1684 1660 (C CCO); dH(500 MHz; CDCl3) 6.978ndash;6.974 (d 1H J 2.0 C CH) 5.644ndash;5.640 (d 1H J 2.0 C CH) 4.281 (s 3H C COMe) 3.643 (s 3H CO2Me) 1.228 (s 9H But) 1.147 (s 9H But); dC(125 MHz; CDCl3) 192.114 166.624 160.923 149.503 147.889 144.575 135.959 122.781 80.306 60.338 51.927 35.137 35.001 29.257 28.527. X-ray analysis of 1a The crystal used for X-ray study had dimensions of 0.4 times; 0.4 times; 0.35 mm. Crystal data C20H26O6 M = 362.41 triclinic space group P1� unit cell dimensions a = 9.3827(7) Aring; b = 9.7857(7) Aring; c = 12.3881(7) Aring; a = 97.993(5)8 b = 93.180(6)8 g = 116.531(5)8 V = 998.85(12) Aring;3 DC = 1.205 Mg m23 T = 298(2) K R indices I 2s(I) = R1 = 0.0496 wR2 = 0.1366; number of unique reflections = 3421 l = 1.54178 Aring;.Data collection and processing. The intensities were measured on a Siemens P4 X-ray diffractometer using Cu-Ka radiation and 2qndash;w. Of the 7387 reflections collected 3421 with I 2s(I) were used for structure determination and refinement. Acknowledgements J. S. N. thanks RRL and CSIR for a research fellowship. A. U. V. thanks the American Cyanamid Co. USA for financial assistance. The authors thank Dr Sasi Kumar ICSN CNRS France and Dr Jessy Mathew Molecumetics Washington USA for high resolution NMR spectra and elemental analyses. References 1 Organic Phosphorus Compounds ed. G. M. Kosolopoff and L. Maier Wiley 1973 New York. 2 B. M. Trost and U. Kasmeir J. Am. Chem. Soc. 1992 114 7933. 3 B. M. Trost J. A. Martinez R. J. Kulawiec and A. F. Indolesa J. Am. Chem. Soc. 1993 115 10 402. 4 (a) M. A. Shaw J. C. Tebby R. S. Ward and D. H. Williams J. Chem. Soc. (C) 1968 1609; (b) P. J. Butterfields and J. C. Tebby J. Chem. Soc. Perkin Trans. 1 1979 1189; (c) J. C. Tebby and I. F. Wilson J. Chem. Soc. Perkin Trans. 1 1979 2133. 5 K. Nozaki N. Sato K. Ikeda and H. Takaya J. Org. Chem. 1996 61 4516. 6 V. Nair and S. Kumar Synlett 1996 1143 and references cited therein. 7 E. Winterfeldt and H.-J. Dillinger Chem. Ber. 1966 99 1558. Paper 7/06272I Received 27th August 1997 Accepted 1st September 19
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