Chemistry of Fischer-type rhenacyclobutadiene complexes. I. Deprotonation, addition/substitution of nucleophilic reagents at α-carbon, and insertion of heteroatoms into rhenium–carbon bonds

Chemistry of Fischer-type rhenacyclobutadiene complexes. II. Reactions with alkynes and sulfonium ylides, and rearrangements induced by nitriles and pyridine

“…The sulfonium ylides Me 2 S@CHC(O)Ph and Me 2 S@C (CN) 2 were prepared by reported procedures [4,5]. The rhenacyclobutadienes (CO) 4 Re(g 2 -C(R)C(CO 2 Me) C(X)) (R ¼ Me, X ¼ OEt (1a), O(CH 2 ) 3 CBCH (1b), NEt 2 (1c); R ¼ CHEt 2 , X ¼ OEt (1d); R ¼ Ph, X ¼ OEt (1e)) were synthesized as described in the accompanying paper [1].…”

“…All general procedures were the same as those described in the immediately preceding paper [1]. IR and NMR spectra were obtained as reported earlier [2,3].…”

“…IR (hexane): m(CO) 2025 (m), 1945 (s), 1729 (w) cm À1 . 1 H NMR (CDCl 3 ): d 7.7-7.1 (m, 5H, Ph), 5.29 (s, 1H, CH), 3.87 (s, 3H, CO 2 Me), 3.80 (m, 2H, CH 2 Me), 2.49 (s, 3H, CMe), 1.25 (t, 3 J ¼ 7:0 Hz, 3H, OCH 2 Me). 13 Alternatively, 2a was prepared from 1a (0.300 g, 0.662 mmol) and PhCBCH (0.075 ml, 0.068 g) in 1.5 ml of toluene in a sealed tube heated at 120°C overnight.…”

“…Yield: 0.044 g (62%). 1 2.3.3. Synthesis of (g 5 -C 5 (Me)(CO 2 Me)(OEt)(Ph)-(Ph))Re(CO) 3 (2d) from (CO) 4 Re(g 2 -C(Me)C(CO 2 -Me)C(OEt)) (1a) and PhCBCPh A solution of 1a (0.100 g, 0.221 mmol) in 10 ml of toluene was treated with 1 equivalent of PhCB CPh (0.040 g), and the mixutre was heated at reflux temperature for 3 h. The workup procedure followed that given in Section 2.3.1.…”

“…Also presented were a number of reactions of 1, viz., deprotonation followed by alkylation at R (R ¼ alkyl), aminolysis at C(OR 0 ), nucleophilic addition (at C(R)) and substitution (at Re) by tertiary phosphine, and insertion of oxygen atom and the isoelectronic NH fragment into the Re@C bonds [1]. This paper focuses on additional chemistry of 1 and derivatives, including reactions with alkynes to yield tetra-and pentasubstituted g 5 -cyclopentadienylrhenium complexes (Cp z Re (CO) 3 (2)) and with sulfonium ylides to give nucleophilic addition at C(R) followed by rearrangement, as well as rearrangements induced by nitriles and pyridine.…”