Allyl phenyl selenides

As has been described for allyl bromide (see preceding paragraph), allyl sulfides and allyl phenyl selenide react with 6-diazopenicillanates 134 under Cu(acac)2 catalysis to give the products of ylide formation and subsequent [2,3] rearrangement 155-159). Both C-6 epimers are formed. The yields are better than with BF3 Et20 catalysis, and, in contrast to the Lewis acid case, no 6[Pg.139]

Allylic phenyl selenides are obtained by the reaction of allylic acetates with diphenyldiselenide and Sml2[233],... 

The only example of the generation of a monocyclic heterocycle by y-bond formation is provided by the thermally promoted conversion of the bisallenyl selenide (143) into the selenophene (144) (78TL1493). The cyclization is conveniently formulated as proceeding via an intramolecular ene reaction. Another electrocyclic process appears to be involved in the conversion of allyl phenyl selenide (145) into 2-methyl-2,3-dihydrobenzo[6]seleno-phene (146) (71TL49). The origin of the minor amount of 2-methylbenzoselenophene (147) which is also formed has not been established. Access to 3-keto-2,3-dihy-drobenzo[h]selenophenes (148) (71KGS333) and 2-arylidene-3-keto-2,3-... 

Ally lie amines (12,121). Coupling of allylic phenyl selenides with aliphatic or aromatic primary amines is possible if the selenide is treated with NCS and N(C2H5)3 in CH3OH at -25° prior to the addition of the amine. Yields are only modest in coupling of highly substituted selenides or amines.1 Example ... 

Optically active amino acids The NCS-promoted rearrangement of allylic phenyl selenides (12,121) when applied to an optically active substrate (1), available from ethyl (S)-lactate, results in an allylic amine (2), which can be converted into an optically active N-protected D-amino acid (3) in 78-84% ee. 

Alternatively, the ambident oi-hetero substituted allyl anions have been utilized as homoenolate equivalents. For example, in the presence of HMPA, allyl phenyl sulfides (251),192 allyl phenyl sulfones (252)192b c and allyl phenyl selenides (253)192d e add to a,(3-enones in a l,4(0)-mode, while allyl phenyl sulfoxides (254) and allyl phosphine oxides (255) afford 1 A j-addition exclusively, irrespective of solvent used.193 Hua has shown that additions of either chiral sulfoxide (254 R1 = R2 = R3 = R4 = H, R5 = p-tolyl) or allyl oxazaphospholidine oxide (256) occur with excellent enantioselectivity (>95% ee).194 Similarly, Ahlbrecht reports that the a-azaallyl (257) adds exclusively in a 1 A j-mode to acceptor (59) to afford 1,5-diketones (Scheme 86).195... 

The ate complex (2) of allyl phenyl selenide reacts somewhat less regioselectively than 1. Even so, it was useful for a synthesis of the pheromone (3) of Diparopsis castanea (equation II).2... 

Allylphenyl selemdes.3 a-Phenylseleno ketones react with trimethylsilylmethyllithium to afford an adduct that on treatment with a catalytic amount of SnCl2 loses the elements of (CH3)3SiOH accompanied with a 1,3-migration of the phenylselenyl group to give a primary allyl phenyl selenide. 

HOMOALLYLIC ALCOHOLS B-Allyldiisopino-campheylborane. Allyl phenyl selenide. Allyltri-/i-butyltin. Chromium(II) chloride. Crotyltrimethylsilane. Diethylftributyl-stannyl)aluminum. (2R,4R)-Pentanediol. Pinacol chloromethaneboronate. Tin-Aluminum. Titanium(lV) chloride. 

Homoallylic alcohols.1 The anion (LDA) of allyl phenyl selenide reacts with a trialkylborane in THF at - 78° to form an ate complex (a) which rearranges at 0° to the complex b. An allylic rearrangement of b to c occurs at 25°. Reaction of b with an... 

AUylic amines. Allylic phenyl selenides on reaction with NCS (excess), an alkyl carbamate, and triethylamine at room temperature are converted into the corresponding rearranged carbamate-protected primary allylic amines. 

Reaction with p,y-unsaturated acids. Phenylselenolactonization (8, 26-28) is the usual reaction of benzeneselenenyl chloride with 7,6- or 6,e-unsaturated acids. The reaction with acyclic /3,y-unsaturated acids results in adducts that are converted by base into allyl phenyl selenides or, phenylselenolactones. The first reaction is favored by a /3-substituent, and the second by a y-substituent. ... 

It has been reported that, in the presence of a palladium catalyst, diphenyl diselenide and samarium diiodide react with allylic acetates to give allylic phenyl selenides under mild conditions (Scheme 12) [18]. In this case, however, the nucleophilic benzeneselenolate was not proposed as an intermediate of the reaction. 

Competitive experiments of allyl phenyl sulfide and allyl phenyl selenide with this system indicate that oxidative addition of the organic selenide is faster. The equilibrium displacement between the allylic sulfide and 7 -allylic complex depends on the actual precursor for Pd(0) phosphine complexes (Equation (41)). The stereochemistry of the reverse reaction on 7/ -cyclohexenyl palladium thiolate dimers (nucleophilic attack of sulfide) has been determined to be trans. According to the principle of microscopic reversibility, the oxidative addition of allylic sulfides must occur with inversion of configuration. 

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