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Chelation or Non-Chelation Control in Stereoselective Reactions of Titanium Reagents with Chiral Alkoxycarbonyl Compounds.

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Using 1 and 2 as starting compounds, we have now
been able to prepare 3, a compound of type C in which
the amino(imino)phosphane 1 is coordinatively bridged as
four-electron donor to two rhenium atoms via the imino-N
atom and the P atom.
R = CbLIe3, R' = S i M e ,
3[41forms yellow-orange crystals which are sensitive to
hydrolysis, readily soluble in benzene, moderately soluble
in ether, and sparingly soluble in pentane.
The crystal structure analysis[51shows (Fig. I) that trans1 isomerizes to cis-1 through the p-q',q'-coordination of
the P=N moiety of the molecule. In the process the NPN
angle widens from 104.9"[21to 122.6", while the PN bond
lengths remain almost unchanged.
[I] a) S. Pohl, J. Orgunomef. Chem. 142 (1977) 185, 195; b) 0. J. Scherer, R.
Tsay, Chem. Ber. 115 (1982) 414; c) 0. J. ScherKonrad, C. Kriiger, Y.-H.
er, R Konrad, E. Guggolz, M. L. Ziegler, Angew. Chem. 94 (1982) 309;
Angew. Chem. Int. Ed. Engl. 21 (1982) 297; Angew. Chem. Suppl. 1982,
[21 S. Pohl, Angew. Chem. 88 (1976) 723; Angew. Chem. Int. Ed. Engl. 15
(1976) 687; S. Pohl, Chem. Ber. 112 (1979) 3159.
[3] a) J. L. Atwood, J. K. Newell, W. E. Hunter, I. Bemal, F. Calderazzo, I. P.
Mavani, D. Vitali, J. Chem. SOC.Dulfon Trans. 1978, 1189; b) F. Calderazzo, D. Vitali, R. Poli, J. L. Atwood, R. D. Rogers, J. M. Cummings, I.
Bemal, ibid. 1981, 1004; c) R. L. Davis, N. C. Baenziger, Inorg. Nucl.
Chem. L e f t 13 (1977) 475.
141 3: a) 1 (0.3 mL, 1.06 mmol) (0.J. Scherer, N. Kuhn, Angew. Chem. 86
(1974) 899; Angew. Chem. Inf. Ed. Engl. 13 (1974) 8111 is added to a suspension of 2 (600 mg, 0.71 mmol) in CH2C12(10 mL) at 0°C under argon,
stirred for a further 1 h at 0°C (orange solution), and the solvent removed
in a vacuum. The residue is taken up in ether (15 mL), filtered over filterflocks and allowed to crystallize out at cu. -90". Yield 400 mg (60%).-b)
'H-NMR (90 MHz, CHZCI2,TMS int.): 6=0.34 (s, 9H, SiCH,), 1.39 (s,
9H, CCH,), 1.74 (s, 9H, CCH3); "C{'H)-NMR (200 MHz, CDCI,, TMS
int., 253 K): 6(CO on Re(N)): 192.1 (s), 191.8 (s) (2CO); 6(CO on Re(P)):
= 8 .188.5
(d), c i ~ - ~ J ~ ~ Hz;
= 9 .188.2
(d), fruns189.9 (d), c i ~ - ~ J ~ ~ Hz;
,JPc= 115.7 Hz; IR (pentane): v(C0)=2060 (m),2035 (s), 2020 (sh), 1980
(m), 1945 (m),1930 (s), 1920 (s), 1900 (w).
[5] Monoclinic, space group P2,, 2 = 2 ; u= 8.944(2), b = 16.246(3),
c = 10.280(3)
b= 115.86(3)"; 1846 independent reflections; R=0.066,
R,=0.075. Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Energie Physik Mathematik, D-7514 Eggenstein-Leopoldshafen, on quoting the depository
number CSD 50517, the names of the authors, and full citation of the
Chelation or Non-Chelation Control in
Stereoselective Reactions of Titanium Reagents with
Chiral Alkoxycarbonyl Compounds**
By Manfred T. Reetz*, Kurt Kesseler, Susi Schmidtberger,
Bernd Wenderoth, and Ruiner Steinbach
Fig. 1. Structure of 3 in the crystal. Selected bond lengths
and angles ["I:
PI-Nl 1.56(2), Pl-NZ 1.66(2), PI-Re1 2.481(6), Rel-Brl 2.626(2),
Rel-Br2 2.578(3), Re2-Brl 2.625(2), Re2-Br2 2.631(2), NI-Re2 2.21(2),
111.9(7), Nl-PI-N2
Re1 ... Re2 3.603(1), N1-PI-Re1
119.7(9), PI-Nl-ClI
121(1), Brl-Rel-Br2
Brl-Re2-Br2 82.75(9), Rel-Brl-Re2
86.67(5), Rel-Br2-Re2
Dihedral angle between the faces RelBrlBr2 and Re2BrlBr2 134.4; sum of
angles at PI: 356.0, NI: 359.7, N2: 359.1.
3 is the first representative of the class of substances
EP=~P,, ) ,n = 2i3a1;E = S, Se
or Te, n = ltSbl,
in which the ligand with E-E bridge is replaced by one with a four-electron donor double-bond system (-P=N-).
The shortening of the bond length
(2.308(6)+ 1.56(2) A) on going from the P-P[3a1 to the P-N
bridge is so drastic that the molecule compensates for this
by the Re(p-Br),Re fragment folding itself stronger about
the Br-Br axis (angle between the normals to the ReBr,
planes=45.6" in the case of 3 and 23.4" in the P-P deriv a t i ~ e ' ~ ~the
' ; Re.. .Re distance becomes shorter (3 :
3.603(1), P-P derivative: 3.890(1)
and the two edgesharing coupled distorted octahedra are oriented markedly
more towards face-sharing coupling (Re.. .Re distance in
the case of the Br face-sharing [(OC)3Re(p-Br)3Re(CO)3]-:
3.46 A[3c1).
The "P{'H}-NMR signal[4b1(200 MHz, CD2C12,H3PO4
ext.) of 3 (with the cis-1 ligand), with 6=303.4 is shifted
only slightly upfield compared to that of the free ligand
trans-1 (327.4l4"]).
Received: July 8, 1983; revised: August 10, 1983 [Z 456 IE]
German version: Angew. Chem. 95 (1983) 1003
Angew. Chem. Znr. Ed. Engl. 22 (1983) No. I 2
Following the pioneering work of Cram on chelation
control in Grignard additions involving alkoxycarbonyl
compounds['], a number of publications on this topic have
appearedr2]. We wish to report that chelation-controlled
1,2- and 1,Casymmetric inductions are possible using Lewis acidic titanium reagents, and that diastereoselectivity
can be reversed by changing the ligands at titaniumC3'(nonchelation control). This extends our previous work on 1,3asymmetric induction involving p-alkoxy aldehydes"'].
The reaction of the Lewis acidic H3CTiC13[31with aldehyde 1 leads via chelate 2 to the adducts 3 and 4 (92 :8).
Chelation mediated 1,2-asymmetric inductions of 90-96%
are also observed if 1 is first chelated with TiCI, and subsequently treated with dialkylzinc, allylsilanes, or silyl enol
[*] Prof. Dr. M. T. Reetz, K. Kesseler, S. Schmidtberger, Dr. B. Wenderoth,
Dr. R. Steinbach
Fachbereich Chemie der UniversitBt
Hans-Meenuein-Strasse, D-3550 Marburg (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0 Verlug Chemie GmbH. 6940 Weinheim, 1983
0570-0833/83/1212-0989 S 02.50/0
Einhefier 985- 988
Reaction of the 2-configurated trimethylsilyl enol ether
of propiophenone with 1/TiCI4 leads to formation of
practically only one (9) of the four possible diastereomers;
this product, formed via chelation control, has syn-stereochemistry at the two new chiral centers. Since the Mukaiyama aldol addition normally affords mixtures of syn/
anti-adducts"], an unusual phenomenon is operating.
SnCl, gives the same result.
With titanium reagents which contain alkoxy- instead of
chloro-ligands, the 1.2-asymmetric induction can be reversed: e.g., the weak Lewis acid H3CTi(O-iPr)3 1313' reacts
with 1 to give 3 and 4 in the ratio 8 :92.The observed stereoselectivity, which can be accounted for by Anh's modhas not been observed previously using any other methylmetal reagents.
13 allows for this type of control even in complicated
cases, e.g., in the reaction with a protected furanose. Reversal of diastereoselectivity is also observed in the addition of the tris(isopropoxy)titanium enolate derived from
propiophenone (9 :10 = 13 :87).
Unusually high 1,Casymmetric induction is achieved by
chelating the y-benzyloxy aldehyde 19 with TiCL.
8 5 : 15
Received: July 27, 1983;
revised: September 5, 1983 [Z 488 IE]
German version: Angew. Chem. 95 (1983) 1007
The complete version of this communication appears in:
Angew. Chem. Suppl. 1983, 1511- 1526
[I] D. J. Cram, K. R. Kopecky, J. Am. Chem. SOC.81 (1959) 2748; review on
stereoselectivity in acyclic systems: P. A. Bartlett, Tetrahedron 36 (1980)
121 W. C. Still, J. H. McDonald, Tetrahedron Lett. 21 (1980) 1031; W. C.
Still, J. A. Schneider, ibid. 21 (1980) 1035, and literature cited therein.
[3] General review on this principle: M. T. Reetz, Top. Curr. Chem. 106
(1982) 1; see also B. Weidmann, D. Seebach, Angew. Chem. 95 (1983)
13; Angew. Chem. Int. Ed. Engl. 22 (1983) 31.
[7] T. Mukaiyama, K. B. Banno, K. Narasaka, J. Am. Chem. SOC.96 (1974)
7503; for chelation control in the addition of diketene to a chiral aldehyde see: T. Izawa, T. Mukaiyama, Chern, Lett. 1978, 409.
[lo] M. T. Reetz, A. Jung, J. Am. Chem. SOL.105 (1983) 4833.
[14] N. T. Anh, Top. Curr. Chem. 88 (1980) 40; other recent examples of Felkin-Anh products: Y.Yamamoto, K. Maruyama, Heterocycles 18 (1982)
357; W. R. Roush, D. J. Hams, B. M. Lesur, Tetrahedron Lett. 24 (1983)
By Giinther Maier*, Manfred Hoppe, and
Hans Peter Reisenauer
Dedicated to Professor Karl Winnacker on the occasion
of his 80th birthday
The long-soughtl'al title compound 3 is interesting for a
number of reasons: Is there, by analogy to the tetra-terfbutyl derivativeL2',a route from 3 to the unsubstituted tetrahedrane 4, or does the photoelimination of CO in an argon matrix lead directly to cyclobutadiene 5 ? If the latter
occurs, can free cyclobutadiene or a CO complex of 5 be
Preparation of 3 : Hydrolysis of methyl 2,3-bis(trimethylsilyI)-2-~yclopropene-I-carboxylate~~~~
with chlorotrimethylsilane/sodium iodide yields the carboxylic acid l a .
Treatment of la with oxalyl bromide leads to formation of
the acid bromide l b , which-without further purification-can be converted into the diazoketone lc. Heating
Finally, chelation control is also feasible with the chiral
ketone 23. Presumably, 24 is the intermediate, since allyltrimethylsilane adds to 23 in the presence of Tic& to afford practically only 25. Weakly Lewis acidic reagents
such as allylmagnesium chloride or allyltitanium tris(diethylamide) afford only 3 :1 mixtures of 25 and 26. Previously, the role played by chelation has only been de'Hduced indirectly from stereochemical
and I3C-NMR spectroscopic studies of 23 in the presence
of TiCI, suggest formation of the chelate 24 before stereoselective introduction of the allyl moiety.
la, R
= C02H;
Ib, R
= COBr;
Ic, R = COCHNz
1,5-bis(trimethylsilyl)tricycl0[2. 1.0.02~5]pentan-3-one2. Desilylation of 2 occurs using KF/dibenzo[ 18lcrown-6. Subsequent gas chromatographic separation (OV 101, lOO"C), which is associated
with considerable losses, leads to a colorless oil. The spectroscopic data of this product (Table l), which is stable at
room temperature, are consistent with assignment to structure 3. Here, the 13C-H coupling constant of C-1/C-5 of
[*I Prof. Dr. G. Maier, M. Hoppe, Dr. H. P. Reisenauer
Institut fur Organische Chemie der Universit&t
Heinrich-Buff-Ring 58, D-6300 Giessen (Germany)
0 Verlag Chemie GmbH. 6940 Weinheim, 1983
[**I Small Rings. Part 49. This work was supported by the Deutsche Forschungsgemeinschaft.- Part 48: T. Loener, R. Machinek, W. Liittke, L.
H. Franz, K.-D. Malsch, G. Maier, Angew. Chem. 95 (1983) 914; Angew.
Chem. Int. Ed. Engl. 22 (1983) 878.
0570-0833/83/1212-0990 $02.50/0
Angew. Chem. Int Ed Engl. 22 (1983) No. 12
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chiral, stereoselective, titanium, reaction, compounds, reagents, chelation, non, alkoxycarbonyl, control
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