ChemInform Abstract: Phosphorus Compounds. Part 97. Synthesis of Polycyclic Phosphorus Cage Compounds Containing Diphosphirane and Phosphirane Units by Tandem Diels‐Alder and Ene Reactions: A Contribution to the Cycloaddition and Enophile Chemistry of Phosphaalkynes.

Abstract

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Cage Chirality of PC Cage Compounds: Highly Diastereoselective Formation of Diastereomeric P5‐Deltacyclenes, Separation of Diastereomers, and Removal of the Chiral Auxiliary

“…We can state that the P1 lone pair of 8 has taken over the position of the bulky stannyl group of 7 a(RR), and the smaller P1ÀH unit of 8 was formed in the place of the P1 lone pair in 7 a(RR). As outlined in the discussion of the CD spectroscopic properties of 8, the position of the P1 À H bond does not strongly influence the CD spectrum of the compound, as long as the absolute configuration of the chiral P 5 (CR) 4 cage itself is not touched by the process. The X-ray data supply proof for that assumption, but there is still a bit of uncertainty about the absolute configuration of P1.…”

“…This became possible with high-yield cyclic addition reactions leading to P À C cages by combining 1 and suitable dienes, polyenes, or related compounds with C=C or C=P double bonds. [4] If triphenylstannyl 1,2,4-triphosphole 2 is used as the diene component in combination with 1, the cyclic addition reaction leads to the chiral stannylated pentaphosphadeltacyclene cage 3 in good yield. [5] The most important aspect of this reaction is the excellent diastereoselectivity, as the 80 % isolated yield of the compound forms exclusively two enantiomers in spite of its seven stereogenic centers (Scheme 1).…”

An Approach to Rigid, Optically Active Chelate Ligands with C2 Symmetry: Dialkylhexaphosphapentaprismanes

“…Some convenient routes to this class of compounds are based on the kinetically stabilized tert ‐butylphosphaalkyne 1 of Becker and co‐workers,2 and in 1989 three groups independently established the chemistry of cage‐structured oligomers of 1 3. The mechanisms of cage formation were evaluated through high‐yielding cyclic addition reactions leading to P–C cages by combining 1 and suitable dienes, polyenes, or related compounds with C=C or C=P double bonds 4. When 1,2,4‐triphosphole 2 was used as the diene in combination with 1 , the cyclic addition reaction led to the chiral stannylated pentaphosphadeltacyclene cage 3a , which contains a triphosphanorbornene unit, a diphosphirane ring, and a secondary phosphane carrying the organyltin fragment.…”