Responsa על בבא מציעא 216:11

Q. A sold his ground, which bordered on B's property, to C for a sum of money plus C's share in a piece of ground C held in partnership with D in another part of town. After the sale was completed and the title conveyed, B pressed his rights as an abutter. Since Maimonides rules that the law of preemption does not apply to the case where a person exchanges his immovables for the immovables of another, C was advised to persuade A to refuse to accept from B, in payment of A's ground, anything but the particular piece of ground A was to receive from C. Accordingly A claimed that C's piece of ground was very precious to him and that he valued it like the "estate of Bar Marion" (B.B. 12b). B, therefore, bought from D his share of the particular ground he held in partnership with C, and offered it to A in lieu of C's share of the same ground. C, however, objected to D's sale claiming that upon the voiding of his transaction with A he would return to his former status as D's partner, and, having the right of preemption on D's share, he would buy such share leaving nothing to A. A and C employed many other tricks and artifices in order to void B's right of preemption.
A. Since C bought A's ground and gave away his own ground in partial payment thereof, he no longer owns the latter ground. Since a person who buys real property desired by an abutter, merely acts as the agent of such abutter (B.B. 108a), C must deliver to B the ground he bought from A, receiving in exchange the ground B bought from D plus a refund of his money. Were B unable to acquire such ground from D, he would have repaid C with money for the ground C gave to A; the value of such ground would have been determined by experts and not by C. C would not have been able to claim that his ground was very precious to him having for him the value of the "estate of Bar Marion", for such claim is valid only when a person is seeking to take away the property of another (in exchange of his own) against the will of the latter who may plead that his property is very precious to him. But in our case C has sold his property to A, and is only entitled to its market price. Moreover, even if the aforementioned sale were not concluded as yet, and an understanding merely existed between A and C that C convey his ground to A on condition that the conveyance of A's ground be without any interference on the part of the abutters, A could not have insisted on exchanging his ground for ground exactly similar to that of C. A could not have attached special importance to C's ground as having the value for him of the "estate of Bar Marion", for the reason already stated. Therefore, B would have been able to pay A with other ground, located in the same town, of equal value as that of C. Many persons have the erroneous notion that the preemptive right of an abutter is void whenever an exchange or real property is involved. Were this true, the parties to a sale of immovables would always add a small piece of ground to the purchasing price in order to place the transaction in the category of exchange of real property, thus turning into a hollow mockery the ordinance of the Rabbis who created the law of preemption for humane reasons. Therefore, whenever we suspect that the circumstances of a sale of real property were specially arranged in order to circumvent the law of preemption, we sustain the preemptive right of the abutter.
SOURCES: Cr. 193; Am II, 199, 200.

Q. A house belonged to three or four partners, one of whom was Leah. An abutting house was sold to Rachel. Leah wanted to buy the latter house and asserted her priority rights as an abutter. Indeed the Talmud rules (B.M. 108b) that an abutter may not assert priority rights, if the buyer is a woman. This law may not apply, however, when the abutter is also a woman.
A. The talmudic law cited above applies even when the abutter is a woman.
SOURCES: P. 285; Mord. B. M. 394. Cf. Agudah B. M. 170.

Q. A negotiated to buy from a Gentile a house which bordered on B's property. After A agreed with the Gentile on the terms of the sale, he withdrew his offer so that the Gentile should lower his price. He warned B not to negotiate with the Gentile since he, A, was still negotiating with him. B, however, disregarded A's warning and bought the house from the Gentile. In defense B claims that he had sought to purchase the house from the Gentile before A began his negotiations. Should B be punished for his act as violating the talmudic injunction against "a poor man turning a cake, and another coming and taking it (Kidd. 59a)?" How long should one refrain from offering to purchase an article which another Jew is seeking to buy?
A. R. Jacob Tam applies the aforesaid talmudic injunction only to mercantile pursuits but not to cases where a person is about to pick up a lost or ownerless object and another snatches it away. For finding a lost object is a rare opportunity and the second person is just as much entitled to the ownerless object as the first person. Buying abutting property from a Gentile is also a rare opportunity and is in the same category as picking up lost objects. Therefore, B is free from any obligation to A. A Jew should not approach a seller where another Jew had already agreed with the seller for the sale of the article, and where the writing of the contract and the scrutiny and transfer of the deed in the Gentile courts are the only things lacking in order to complete the sale. But, the mere offer of a Jew to buy something without the seller's acceptance of the offer, does not restrain another Jew from buying it. If such were the case, it would be very unfair to the seller who would be forced to sell his possessions to the very first bidder, no matter how low the offer, since no other purchasers would dare to buy it. The Torah was very careful, however, not to jeopardize the rights and opportunities of the sellers.
The author claims that the same question was sent to him from Neustadt.
SOURCES: Cr. 276–7; Pr. 1011; Berl. p. 284 no. 334; B. p. 292, no. 366.