J. A m . Chem. SOC.1982, 104, 161-166
161
We presently seek a direct synthesis of the diphosphite to enable dominant exchange mechanism between the molybdenum and a more detailed study of the chelate chemistry. tungsten complexes. Pairwise exchange as observed for the tungsten complex is consistent with previously proposed idealized Acknowledgment. This research was generously supported by pathways based on the interconversion of pentagonal-bipyramidal, capped octahedral, and capped trigonal prismatic g e o m e t r i e ~ . ~ ~ ~the ~ National Science Foundation. A sample of ammonium perrhenate was kindly provided by Dr. M. Lindner of the Lawrence The Chelate (CH30),POP(OCH3)2 Ligand. To our knowledge, Berkeley Laboratory. Analyses were performed by Mr. V. Tatetramethyl diphosphite has never been described in the literature shinian of the U.C.B. Chemistry Department Microanalytical either as the free molecule or as a ligand in a transition-metal Laboratory and the mass spectrometric analyses performed by complex although the closely related diphosphite (CzH50),POMs. Sherry Ogden of the U.C.B. Mass Spectrometric Laboratory. P(OC2H5), has been prepared and utilized to prepare transiE.L.M. is indebted to the Miller Institute for Basic Research in tion-metal complexes in which the diphosphite serves as a bridging Science for a grant in the form of a Miller Professorship. ligand between two metal All the (CH30),POP(OCH3)2 derivatives of molybdenum, tungsten, and rhenium deRegistry No. Mo[P(OCH,),]~,37478-27-6; W[P(OCH,),],, 7341 1scribed in this article have been colored-brown for the first two 63-9;H~Mo[P(OCH,)~],, 798 15-40-0; H~Mo[P(OCH,)~]~, 79803-06-8; HZW[P(OCH3)3]j,7341 1-64-0; H,W[P(OCH,),],, 73460-89-6; Mo[Pmetals and purple for HRe[P(OCH3)3]3[(CH30)2POP(OCH,)JS(CO), 37478-26-5; W[P(OCH,),],(CO), 37478-28-7; trans(OCH,),]-whereas the strict "per" trimethyl phosphite analogues MO[P(OCH,),]~(CO)~, 79854-39-0;rran~-W[P(0CH,)~],(C0)~, were colorless. Apparently, the presence of the four-membered 79854-40-3; ~ ~ ~ - M o [ P ( O C H ~ ) ~ ] ~1563 (CO 1-23-9; ) , , MO[P(OCH,)~],cycle introduces electronic or steric features whereby electronically [(CH,O)2POP(OCH3),], 79803-07-9; W[P(OCH3),]4[(CH30)2POP(Oexcited states are readily accessible by thermal a c t i ~ a t i o n . ~ ~ CH,),], 79803-08-0;Mo[P(OCH~),]S(NO)', 79803-09-1;Mo[P(OCH3)313(NOh, 79803-10-4;IW~P(~CH~)~ls[P(OCH~)~lt)(CF~~~ 79803-12-6;HW[P(OCH3)3]4(02CCF,), 79815-39-7; HW[Pd P \ O (OCH,)3]6+, 79803-13-7;H,W[P(OCH3),]3[(CH30)zPOP(OCH,),I, P '' 79803-14-8; Re,[(P(OCH,),],,, 76281-32-8;HRe[P(OCH3),],, 7642879815-41-1; HRe[P(OCH,),],28-9;Re[P(OCH3)3]s[P(0)(OCH3)z], (43) Muetterties, E.L.;Guggenberger, L. J. J . Am. Chem. SOC.1974, 96, [(CH,O),POP(OCH,),], 79803-15-9;H3Re[P(OCH3),J4,79803-16-0; 1748. H2Re[P(OCH,),] 79803-17-1; H,Re[P(OCH,),] ,(OzCCF3),79803(44)As discussed in ref 41, the geometry of the molybdenum complex can 79803-19-3;MoCI,, 10241-05-1 ; 18-2;fran~-HRe[P(0CH,)~],(C0), be considered as a hydride (equatorial) edge capped trigonal bipyramid if the WCI6, 13283-01-7; ReCI,, 13596-35-5; MOOCI3(NCSH,),, 79803-20-6; trifluoroacetic ligand is treated as a unidentate ligand. In this structural MoCl4(0C,H8),, 16998-75-7; WOC13(NC,H,)3,79803-21-7; ReCI,(Napproximation of a trigonal-bipyramidal pseudo-five-coordinate species with ReOC13(NCSH5)2, 18195-83-0; CF,COOH, 76-05C,H,),, 79803-22-8; axial and equatorial sets of phosphorus ligands, the expected polytopal rear1. rangement involving a square-pyramidal intermediate or transition state would also be a pairwise exchange process. (45) Haines, R. J.; Pidcock, A,; Safari, M. J . Chem. Soc., Dalron Trans. (48)A related diphosphite, H2P2052-,spans two closely set platinum atoms 1977. 830. in [K4Pt2H,P,02,].2H20, a complex which is purple and intensely lumines(46)DuPreez, A. L.;Marais, I. L.; Haines, R. J.; Pidcock, A,; Safari, M. cent. The Pt-Pt interaction was proposed as the origin of the luminescence. J . Organomet. Chem. 1977, 141, C10. Pinto, M. A. F. D. R.; Sadler, D. J.; Neidle, S.; Sanderson, M. R.; Subbiah, (47)Cotton, F.A.; Haines, R. J.; Hanson, B. E.; Sekutowski, J. C. Inorg. A,; Kuroda, R. J . Chem. SOC.,Chem. Commun. 1980, 13. Chem. 1978, 17, 2010.
,',
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Reaction of Bicycle[ 3.2.1 ]octa-2,6-diene with 1,2,4-Triazoline-3,5-diones:Competitive Dipolar and Homocycloaddition Waldemar Adam,*+Ottorino De Lucchi,+Karl Peters,*Eva-Maria Peters,*and Hans Georg von Schneringt Contribution from the Institute of Organic Chemistry, University of Wiirzburg, 0 - 8 7 0 0 Wurzburg, A m Hubland, West Germany, the Department of Chemistry, University of Puerto Rico, Rio Piedras, Puerto Rico 00931, and the Max-Planck-Institut fur Festkorperforschung, 0 - 7 0 0 0 Stuttgart 80, West Germany. Received February 2, 1981, Revised Manuscript Received July 13, I981 Abstract: The nonconjugated bicyclo[3.2.l]octa-2,6-diene(1) affords with 1,2,4-triazolin-3,5-diones the homocycloadducts 6. An X-ray structure determination confirms cyclopropane formation as the preferred mode of homoreactivity. Dipolar cycloaddition takes place both at the C2-C3 and the C6-C7 sites, leading to the rearranged urazoles 7 and 8 (major product), respectively. As expected, attack at the more strained double bond (c&7 attack) predominates. Ene reactions and [2 21 cycloadditions are not observed. The urazoles 6-8 have been converted to their respective azoalkanes 10-12 via oxidative hydrolysis.
+
Bicyclo[3.2. I]octa-2,6-diene (1) should be an interesting and useful substrate for exploring competitive cycloaddition behavior in view of its great diversity in possible reaction modes with dienophiles. Although [2 41 cycloaddition is not possible since
+
*Direct correspondence to this author at the Wiirzburg address. Universities of Wiirzburg and Puerto Rico.
Max-Planck-Institute.
+
1 is a nonconjugated diene, it could undergo [2 21, ene, homo, and dipolar reactions with suitable dienophiles (Figure 1). When triazolinediones (TAD) are used as dienophiles, these various cycloaddition modes would afford a maximum of nine products, Le., urazoles 2-9. For example, [2 21 cycloadditions' at the
+
(1) (a) Seymour, C. A,; Greene, F. D. J . Am. Chem. Soc. 1980, 102,6384. (b) Adam, W.; De Lucchi, 0. Tetrahedron Letf. 1981, 22, 929.
0002-7863/82/1504-0161$01.25/00 1982 American Chemical Society
162 J. A m . Chem. SOC.,Vol. 104, No. 1, 1982 A'
8
A*
a
d
R+R
Adam et al.
=
-CO-N(RYCO-
-9
ene
Figure 1. Possible cycloaddition modes of bicyclo[3.2.l]octa-2,6-diene (1) with TAD.
R=Me,Ph
C2-C' and C S c 7 double bonds would lead to the urazoles 2 and 3, respectively, while ene reactionIav2a t C4 would afford 4. The two possible homocycloaddition modes' a t the C2-C7 and c3-c6 sites would produce the urazoles 5 and 6,respectively. On the other hand, dipolar cycloaddition4at the less strained C2
