J. Org. Chem. 1984,49, 174-176
174
H, J = 6.0 Hz, CH,CO), 5.11 (m, 1H, CHOAc). Anal. Calcd for C10H1803: C, 64.45; H, 9.76. Found: C, 64.36; H, 9.87. Other 1,3-keto acetates were synthesized analogously. 3d: purified by column chromatography on silica gel (hexane-ether 50:l); 'H NMR (CC14)6 1.51 (br s, 10 H, CHZ), 2.06 (s, 3 H, CH,CO), 2.13 (s, 3 H, OCH,), 3.10 (8, 2 H, CH2CO). Anal. Calcd for CllHl80$ C, 66.62; H, 9.17. Found: C, 66.24; H, 9.32. 3e: purified by distillation [bp 120 "C (20 mm; Kugelrohr bath temperature)]; 'H NMR (CC14) 6 1.71 (d, 3 H, J = 5.8 Hz, CH,C=C), 2.00 ( 8 , 3 H, CH,CO), 2.14 (s, 3 H, OCH,), 2.68 (dd, 2 H, J = 6.0, 2.0 Hz, CH2CO), 5.20-6.25 (m, 3 H, CHOAc and CH=CH). Anal. Calcd for CgH1403: C, 63.50; H, 8.31. Found: C, 63.06; H, 8.44. 3f purified by column chromatography on silica gel (hexane-ether 30:l); 'H NMR (CC14)6 2.04 (s, 3 H, CH,CO), 2.17 (s, 3 H, OCH,), 2.80 (dd, 2 H, J = 8.0, 2.0 Hz, CH,CO), 5.76-6.34 (m, 2 H, CHOAc and CH=CPh), 6.72 (d, 1 H, J = 15 Hz, C= CHPh), 7.35 (br s, 5H, CBHS).Anal. Calcd for C14H1603: C, 70.87; H, 7.34. Found: C, 71.21; H, 7.05. Registry No. la, 83650-02-6; lb, 87763-89-1; IC, 87763-90-4; Id, 87763-91-5; le, 87763-92-6; lf, 67964-39-0; 2a, 87763-93-7; 2b, 87763-94-8; 2c, 87763-95-9; 2f, 87763-96-0; 3a, 87763-97-1;3b, 87763-98-2;3c, 56894-87-2; 3d, 87763-99-3; 3e, 87764-00-9;3f, 87764-01-0;4,513-31-5;5,87764-02-1;CH,(CHz),CHO, 110-62-3; PhS(CHz)2CHO, 27098-65-3; PhCHO, 100-52-7; EtOZC(CH2)&HO, 692-87-5; NC(CH&$H(OCH,)2, 14618-78-1;CH&H=CHCHO, 4170-30-3; PhCH=CHCHO, 104-55-2;benzaldehyde ethylene ketone, 936-51-6;cyclohexanone, 108-94-1;tin, 7440-31-5.
Synthesis of Carbon-13 Labeled Aldehydes, Carboxylic Acids, and Alcohols via Organoborane Chemistry George W. Kabalka,* Mark C. Delgado, Usha S. Kunda, and Sastry A. Kunda Chemistry Department, University of Tennessee, Knoxville, Tennessee 37996 Received April 26, 1983 Isotopically labeled materials have played a unique role in chemical and biological research.'S2 T h e regiospecific incorporation of carbon-13 has become increasingly important in recent years with the advent of the multinuclear NMR instruments and promises to assume an even greater role in medical research as the new whole-body multinuclear NMR scanners become more ~ i d e s p r e a d . ~The ~~ enriched materials that are required for biological and medical studies often present formidable synthetic challenges due to the variety of functional groups that impart the physiological activity to the molecules of interest. The traditional incorporation routes for carbon-13 (Grignard reactions, hydrolysis of labeled nitriles, oxidation of labeled methyl groups, etc.,) are often unsuitable for synthesizing these functionally substituted molecules. Organoboranes have been utilized to prepare a wide variety of functionally substituted reagent^.^^^ In recent years, we have used the organoboranes to incorporate a number of isotope^.^,^ I t occurred to us that the carbo(1) Ott, D. G. "Syntheses with Stable Isotopes of Carbon, Nitrogen, and Oxygen"; Wiley: New York, 1981. (2) Evans, E. A. "Radiotracer Techniques and Applications"; Dekker: New Ynrk. 1977. -- . . (3) Bottomley, P. A. Reu. Sci. Instrum. 1982, 53, 1319. (4) Jaffe, C. C. Am. Sci. 1982, 576. (5) Brown, H. C. 'Organic Synthesis Via Boranes"; Wiley-Intencience: New York, 1975. (6) Pelter, A.; Smith, K. In "Comprehensive Organic Chemistry"; Barton, D., Ollis, W. D., Eds.; Pergamon Press: Oxford, 1979. (7) Kabalka, G. W.; Sastry, K. A. R.; McCollum, G. W.; Lane, C. A. J . Chem. SOC.,Chem. Commun. 1982, 62. ----I
nylation reaction developed by Brown and his co-workers would be an ideal method for regiospecifically incorporating carbon-13.*11 We now report that the carbonylation of organoboranes using carbon-13 enriched carbon monoxide produces the labeled aldehydes in excellent yield. Furthermore, the 13C-labeled aldehydes are readily converted into the corresponding 13C-labeledcarboxylic acids and alcohols. The synthesis of the labeled carboxylic acids could be carried out in a variety of ways, including a direct oxidation of the initial organoborane adduct. However, we find that silver oxide oxidation of the aldehydes leads to higher yields of the acids. T h e synthesis of the carbon-13-labeled alcohols could also be achieved in a number of ways, including the direct hydrolysis of the initially formed organoborane adductg (replacing the oxidation-reduction sequence). We find that higher yields are obtained by avoiding the harsh, direct hydrolysis reaction. We prefer to reduce the aldehyde with a borane reagent. Since the initial step in the sequence involved a hydroboration, few difficulties are encountered with a borane reagent in the final step. Our results are summarized in Table I.
Experimental Section Melting points and boiling points are uncorrected. Routine NMR spectra were recorded on a Varian Associates T-60 spectrometer. All chemical shifts are reported in parts per million downfield from Me4Si. 13C NMR spectra were run on a JEOL FX-SOQ spectrometer and referenced to external CC14,CDCl,, or acetone-ds. The mass spectra were obtained with a HP-5982-A GC-mass spectrometer. Elemental Analyses were performed by Galbraith Laboratories, Knoxville, TN. Commercially available samples (Aldrich) of cyclohexene, 10undecen-1-01, 1-nonene, and safrole were distilled prior to use. 3-(p-Tolylthi0)-2-methylpropene'~ and S-BBN', were prepared accordkig to published procedures. Hyc2oboration. General Procedure. 9-BBN (10 mmol,33.3 mL of a 0.3 M solution in THF) was placed in a dry, 50-mL, nitrogen-flushed flask fitted with a septum inlet and cooled to 0 "C. The alkene (10 mmol) was added via syringe and the solution stirred overnight at room temperature to yield the corresponding organoborane. [For alkenes containing acidic hydrogens, a twofold excess of 9-BBN was employed during the hydroboration.] Carbonylation. General Procedure. The organoborane (10 "01) was cooled to 0 "C and potassium triisopropoxyborohydide (KIPBH) (10 mmol, 10 mL of a 1.0 M solution) was then added. [Caution: excess KIPBH will inhibit the uptake of CO.] An atmosphere of carbon-13-enriched carbon monoxide was then maintained over the solution by using a syringe needle connected to a rubber bladder containing the 13C-enrichedCO. (An initial flush of the Nz atmosphere with 13C0 is helpful.) The mixture was stirred vigorously for 30 min, and then NaOAc (12 mmol, 12 mL of a 1.0 M solution) and H,Oz (12 mmol, 1.3 mL of a 30% solution) were added at 0 "C to oxidize the intermediate organoborane complex to form the 13C-labeledaldehyde. Excess diethanolamine was then added to precipitate the borinic acid bypr~duct.'~The mixture was saturated with NaCl and the product extracted into ether. The ether was removed, and the aldehyde was purified via column chromatography. Oxidation. General Procedure. The crude aldehyde was added to a suspension of freshly prepared AgzO [AgNO, (30 mmol, 30 mL of a 1.0 M solution) is mixed with NaOH (30 mL of a 2.0 (8) Kabalka, G. W.; Gooch, E. E. J.Chem. Soc., Chem. Commun. 1981, 1011. (9) Brown, H. C.; Rathke, M. W. J. Am. Chem. SOC. 1967,89, 2740. (10)Brown, H. C.; Hubbard, J. L.; Smith, K. Synthesis 1979, 701. (11) Preliminary results in: Kabalka, G. W.; Delgado, M. C.; Sastry, U.; Sastry, K. A. R. J. Chem. SOC.,Chem. Commun. 1982, 1273. (12) Kabalka, G. W.; Hedgecock, H. C. J. Org. Chem. 1975,40, 1776. (13) Soderquist, J. A.; Brown, H. C. J. Org. Chem. 1981, 46, 4599. (14) Lawesson, S. 0. Ark. Kemi 1956, 10, 171.
0022-3263/84/1949-0174$01.50/0 0 1984 American Chemical Society
J. Org. Chem., Vol. 49, No. 1, 1984 175
Notes
R
5 c
M s~lution)].'~The mixture is heated at 50 "C for 30 min. The product is isolated by extraction into 2 M NaOH. The solution was acidified to yield the I3C-labeled carboxylic acid. Reduction. General Procedure.The aldehyde (5 "01) was dissolved in dry THF and cooled to 0 "C. BH3.THF (6 mmol, 3 mL of a 2 M solution) was added and the mixture stirred for 15 min at 0 "C. Water (10 mL) was then added to destroy the excess BH,. The solution was acidified (HCl) and saturated with NaCl and the product extracted into ether. Decanal. The organoborane ( 5 mmol) was carbonylated as described in the general procedure. The aldehyde was purified on a silica gel column eluted with petroleum ether to yield 0.67 g (85.4%);(2,4dinitrophenyl)hydrazonederivativemp 104.5-105.5 "C (lit.16 mp 104 "C); 13C NMR (CC14)6 198.8; 'H NMR (CC14) 6 0.9 (br, t, 3 H, CH3), 1.3 (br s, 14 H, aliphatic CH,), 2.3 (br t, 2 H, CHZCHO), 9.6 (t, 1 H, CHO). Cyclohexanecarboxaldehyde. The organoborane (5 mmol) was carbonylated as described in the general procedure. The aldehyde was purified on a silica gel column eluted with petroleum ether to yield 0.47 g (84%); (2,4-dinitrophenyl)hydrazone derivative mp 173-173.5 "C (lit." 172-173 "C); 13CNh4R (CCW 6 200.2; 'H NMR (CC14)6 1.0-2.3 (br m, 11 H, CH2, CH), 8.5 (d, 1 H, CHO). 12-Hydroxydodecanal. The organoborane (5 mmol) was carbonylated as described in the general procedure. The aldehyde was purified on a silica gel column eluted with 40% ethyl acetate-petroleum ether to yield 0.85 g (85%); (2,4-dinitropheny1)hydrazone derivative mp 100-101 "C; 13CNMR (CDC13) 6 203.2; 'H NMR (CDC13) 6 1.3 (br s, 18 H, aliphatic CH2), 2.3 (br t, 2 H, CH,CHO), 2.4 (s, 1 H, OH), 3.6 (t, 2 H, CH20), 9.6 (t, 1 H, CHO). 4-(p -Tolylthio)-3-methylbutanal. The organoborane (5 mmol) was carbonylated as described in the general procedure. The aldehyde was purified on a silica gel column eluted with 5% ethyl acetate-petroleum ether to yield 0.86 g (83%); (2,4-dinitropheny1)hydrazonederivative mp 111-112 "C (lit.18 113 "C); 13CNMR (CDCl3) 6 201.6; 'H NMR (CDC13) 6 1.0 (d, 3 H, CH3), 1.5 (br m, 1H, CH), 2.2 (br m, 2 H, CH2),2.3 (s, 3 H, ArCH3), 2.8 (d, 2 H, SCH2),7.2 (AiX',, 4 H, Ar H), 9.6 (t, 1 H, CHO). 4-[3,4-(Methylenedioxy )phenyllbutanal. The organoborane (5 mmol) was carbonylated as described in the general procedure. The aldehyde w a purified on a silica gel column eluted with 10% ethyl acetate-petroleum ether to yield 0.78 g (81%); (2,4-dinitropheny1)hydrazone derivative mp 267-268 "C; 13C NMR (CDC13)6 198.4; 'H NMR (CDCl,) 6 1.8 (m, 2 H, CH,CH,CH,), 2.5 ( m , 4 H,ArCH2,CH2CHO),5.8 (s, 2 H, OCH20),6.6 (s, 3 H, Ar H), 9.5 (t, 1 H, CHO). Decanoic Acid. The organoborane (10 mmol) was carbonylated and oxidized as described in the general procedure to yield 1.62 g (94%); bp 270 "C (lit?' 270 "C); 13C NMR (acetone-d6) 6 179.6; 'H NMR (CC14)6 0.9 (br t, 3 H, CH3), 1.3-1.7 (br s, 14 H, aliphatic CH,), 2.3 (t,2 H, CH,COOH), 10.6 (s, 1 H, COOH). Cyclohexanecarboxylic Acid. The organoborane (10 mmol) was carbonylated and oxidized as described in the general procedure to yield 1.2 g (94%);bp 232 "C (lit.19232 "C); 13C NMR 6 177.9; 'H NMR (acetone-d6)6 1.0-2.3 (br m, 11 H, (a~et0ne-d~) CH2, CH), 8.0 (9, 1 H, COOH). 12-Hydroxydodecanoic Acid. The organoborane (10 mmol) was carbonylated and oxidized as described in the general procedure to yield 2.12 g (98%);mp 79-81 "C (lit?' 81 "C); 13C NMR (CDC13) 6 178.2; 'H NMR (CDC13) 6 1.1-2.0 (envelope, 18 H, aliphatic CH,), 2.3 (t, 2 H, CH&OOH), 3.7 (t, 2 H, CH20),8.23 ( ~ , H, 2 COOH, CHZOH). 4-(p-Tolylthio)-3-methylbutanoicAcid. The organoborane (10 mmol) was carbonylated and oxidized as described in the general procedure to yield 2.0 g (89%);mp 85-86 "C; 13CNMR 6 174.1; MS, m/e 225 (calcd 225); 'H NMR (ace(a~et0ne-d~) ~~
(15) Pearl, I. A."Organic Syntheses";Wiley: New York, 1963; Collect. Vol. IV, p 972. (16) Allen, C. J. Am. Chem. SOC.1930,52, 2955. (17) Blanchard, E.P., Jr.; Btichi, M. J.Am. Chem. SOC.1963, 85,955. (18) Catch, J. R.;Cook, A. H.; Graham, A. R.; Heilbron, I. J. Chem. SOC.1947, 70, 1609. (19) Haworth, P.J. Chem. SOC.1894,65, 103. (20) KaO, C. H.;Shao-yuan Ma. J. Chem. SOC.1931, 2046. (21) Chuit, P.;Hausser, J. Helu. Chim. Acta 1929, 12, 463.
J. Org. Chem. 1984,49, 176-178
176
tone-d,) 6 1.0 (d, 3 H, CH3), 1.4-1.9 (br m, 3 H, CHCHzCOOH), 2.3 (s, 3 H, Ar CH3), 2.9 (m, 2 H, SCHz),7.3 (AiX'2, 4 H, Ar H), 8.3 (9, 1 H, COOH). Anal. Calcd for Cl2Hl6OZS:C, 64.26; H, 7.19. Found: C, 64.23; H, 7.18. 4-[3,4-(Methylenediaxy)phenyl]butanoic Acid. The organoborane (10 mmol) was carbonylated and oxidized as shown in the general procedure to yield 1.76 g (84%); mp 69-72 "C; 13C NMR (acetone-d,) 6 175.3; MS, mle 209 (calcd 209); 'H NMR (acetone-d,) 6 2.0 (m, 2 H, ArCHzCHz),2.2-2.8 (m, 4 H, ArCHz, CHzCOOH),5.9 (s, 2 H, OCH,O), 6.6 (s, 3 H, Ar H), 9.3 (9, 1 H, COOH). Anal. Calcd for CllH1204: C, 63.46; H, 5.81. Found: C, 63.42; H, 5.99. Decanol. Decanal(5 mmol) prepared and purified 89 outlined in the general Procedure was reduced withBH3.THF to field 0.71 g (90%); 3,5-dinitrobenzoate derivative mp 57.5-58.5 "C (lit.22 57.7 "C); 13CNMR (CCU 6 60.1; 'H NMR (CC14) 6 0.9 (br t 3 H, CH3), 1.3 (br 9, 14 H, aliphatic CHZ), 2.4 (9, 1 HPOH), 3.5 ( t, 2 H, CHZOH). C y c l o h e x ~ e m e t ~ n oCyclohe--bddehyde l. (5 -01) was reeduced with BH,.THF 89 described in the general procedure to yield 0.5 g (88%);3,5-dinitrobenzoate derivative mp 91-92 "C (lit.= 94 "C); 13CNMR (CDC13)6 54.9; 'H NMR (CDCld 6 1.0-2.0 (br m, 11 H, CH,, CH), 3.2 (s, 1 H, OH), 3.4 (d, 2 H, CH,OH). 1,12-Dodecanediol. 12-Hydroxydodecanal(5 mmol) was reduced with BHS-THF as described in the general procedure to yield 0.94 g (93%);mP 80-81 "c (lit.2480.5-81 "c);3,5-dinitrobenzoate derivativemp 89-90 "c; " ( ( 3 3 4 ) 6 60.3'H m (CC14)6 1.3 (br, 20 H, aliphatic CH2),3.6 (t, 2 H, CHzOH). 4-(p-Tolylthio)-3-methylbutanol.4-(p-Tolylthio)-3methylbutanal (5 mmol) was reduced with BH,.THF 89 described in the general procedure to yield 0.94 (90%); 3,5dinitrobenzoak derivative mp 81.5-82.5 "C; 13C NMR (CC1,) 6 59.8; lH NMR (acetone-d,) 6 1.0 (d, 3 H, CH,), 1.3-2.0 (m, 3 H, CH2CHCH3), 2.3 (s,3 H, Ar CHJ, 2.6 (9, 1H, OH), 2.8 (m, 2 H, SCH,), 3.6 (t, 2 H, CHzOH), 7.2 (Az& ' ~' 4 H, Ar H). Anal. Calcd for C~S%O~SN~:C, 56.43; H, 4.98; N, 6.93. ~"d: c, 56.26; H, 5.02; N, 6.82. 4-[3,4-(Meth~lenediox~ )phenylIbutanol. 4-[3,4-(methy1enedioxy)phenyllbutanal (5 mmol) was reduced with BH,.THF as described in the general procedure to yield 0.95 g (98%); 3,5-dinitrobenzoate derivative mp 82-83 OC;i3c NMR (cc4) 6 61.7; 'H NMR (CDCl,) 6 1.5 (m, 4 H, ArCH,CH,CH,), 2.4 (m, 2 H, ArCH,), 3.4 (t, 2 H, CH,OH), 5.8 (s, 2 H, OCH,O), 6.6 (s, 3 H, Ar H). Anal. Calcd for Cl8Hl6O8N2:C, 55.67; H, 4.15; N, 7.21. Found: C, 55.57; H, 4.02; N, 7.16. 9
'v
Acknowledgment. We thank the Department of Energy (DE-AS05-90EV10363) for support of this research. Registry No. 1-Nonene, 124-11-8; cyclohexene, 110-83-8; 54844-24-5; safrole, 94-59-7; 3-(p-tolylthio)-2-methylpropene, 10-undecen-1-01, 112-43-6; decanal-13C, 87803-55-2; cyclohexanecarb~xaldehyde-'~C,87803-56-3; 4-[3,4-(methylenedi~xy)phenyl]butanal-'~C, 87803-57-4; 4-(p-tolylthio)-3-methylbutanal-13C, 87803-58-5;12-hydro~ydodecanal-'~C, 87803-59-6; decanoic-13Cacid, 84600-66-8; cyclohexanecarboxylic-'3C acid, acid, 50530-16-0;4-[3,4-(methylenedioxy)phenyl]carboxylic-13C 84600-67-9;4-Cp-tol~lthio)-3-meth~lbutanoic-'~C acid, 84600-68-0; 12-hydro~ydecanoic-'~C acid, 84600-69-1;l-decanol-13C,8780360-9; cycl~hexanemethanol-~~C, 65305-14-8; 4-[3,4-(methylenedio~y)phenyl]-l-butanol-'~C, 87803-61-0; 4-(p-tolylthio)-3methyl-l-b~tanol-'~C, 87803-62-1;1,12-d0decanediol-'~C,8780387803-64-3; cy63-2; decanal-13C 2,4-dinitrophenylhydrazone, clohexanecarboxaldehyde-'3C 2,4-dinitrophenylhydrazone, 87803-65-4;12-hydro~yddecanal-'~C 2,4-dinitrophenylhydrazone, 87803-66-5; 4-(p-tolylthi0)-3-methylbutanal-'~C 2,4-dinitrophenylhydrazone, 87803-67-6;4-[3,4-(methy1enedioxy)phenyllb~tanal-'~C 2,4-dinitrophenylhydrazone, 87803-68-7;l-decanol-13C 3,5-dinitrobenzoate, 87803-69-8;cycl~hexanemethanol-'~C 3,5dinitrobenzoate, 87803-70-1;1,12-d0decanediol-'~C3,5-dinitrobenzoate, 87803-71-2; 4-(p-tolylthi0)-3-methylbutanal-~~C 3,5dinitrobenzoate, 87803-72-3;4-[3,4-(methy1enedioxy)phenyllbutanol-13C3,5-dinitrobenzoate, 87803-73-4;9-BBN, 280-64-8. (22)Reichstein, T. Helu. C h i n . Acta 1926,9, 802. (23)Natta, G.; Pino, P.; Mantica, E. Gazz. Chim. Ztal. 1950,80,680. (24)Kariyone, T.;Isoi, K. Pharm. SOC.Jpn. 1956,76,473.
Convenient and Stereospecific Synthesis of Deoxy Sugars. Reductive Displacement of Trifluoromethanesulfonates Ernie-Paul Barrette' and Leon Goodman* Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881 Received July 27, 1983 The replacement of sugar hydroxyls by hydrogen, the preparation of deoxy sugars, is important in natural products chemistry where deoxy sugars are frequently encountered as constituents of these materials. Most of the preparative methods that have been introduced recently involve photolysis24 or other free-radical reactions.5 Although these latter reactions be quite stereoselective, they tend not to be stereospecific,6 and further, they sometimes5 give poor yields when primary hydroxyls are ~ converted to methyl groups. Deoxygenation via S Nreaction by hydride reagents, which would not be subject to the above disadvantages, has seen little use in sugar chemistry because, ordinarily, the inconvenient reagent lithium aluminum hydride is required for the displacements which are limited to the overall conversion of primary hydroxyls to methyl groups; ordinarily activated secondary sugar hydroxyls are too unreactive to be displaced by lithium aluminum hydride but rather suffer cleavage.' The introduction into sugar chemistry of the triflate leaving group by Maradufu and Perlin6 and elaborated by Hall and Millerg has provided a leaving group that permits many displacement reactions to be carried out smoothly a t secondary sugar carbons,lOJ1and we describe below the reaction of sugar triflates,both primary and secondary, with sodium borohydride which, in many cases, can be carried outunder very mild conditions and which can be used, by employing sodium borodeuteride, to stereospecifically introduce deuterium into sugars. T h e reaction of the triflate 212 of 1,2:3,4-di-O-isopropylidene-a-D-galactopyranose(1) gave, with excess sodium borohydride in acetonitrile a t room temperature, an excellent yield of the 6-deoxy sugar 3. By contrast, the
0s
-
I R=H 2 R:S02CF3
3
tri-n-butylstannane reduction of 6-o-(imidazolylthio(1)Senior undergraduate research student, 1981-1982 Present address: Department of Chemistry, Harvard University, MA 02138. (2)Tsuchiya, T.; Nakamura, F.; Umezawa, S. Tetrahedron Lett. 1979, 2805. Horton, D.; Williams, D. M.; Winter-Mihaly, E. Car(3)Bell, R. H.; bohydr. Res. 1977,589109. (4)Binkley, R. W.; Hehemann, D. G. Carbohydr. Res. 1979,74, 337. (5)Rasmussen, J. R.; Slinger, C. J.; Kordish, R. J.; Newman-Evans, D. D. J. erg. Chem. 1981,46,4843 and references therein. (6)Patroni, J. J.; Stick, R. V. Aust. J. Chem. 1979,32, 411. (7)Schmid, J.; Karrer, P. H e h . Chem. Acta 1949,32, 1371. (8)Maradufu, G.A.;Perlin, A. S. Carbohydr. Res. 1974,32, 261. (9)Hall, L. D.; Miller, D. C. Carbohydr. Res. 1976,47,299. (IO) Binkley, R. W.; Ambrose, M. G.; Hehemann, D. G. J.Org. Chem. 1980,45, 4387. (11)Risbood, P. A.;Phillips, T. S.; Goodman, L. Carbohydr. Res. 1981, 94, 101. (12)Curiously, this compound is noted as an intermediate in ref 10, and Hall's manuscripts is cited as the first preparation of 2. However, in ref 9 the attempt to prepare 2, using pyridine as the acid acceptor, yielded the pyridinium triflate salt derived from 1 in 90% yield. The 'H NMR spectrum recorded for 2 in ref 10 does not accord with the spectrum we observed for that compound.
0022-3263/84/1949-Ol76$01.50/00 1984 American Chemical Society
